Wrigley Eye Associates

Eye Movements Reveal Reading Impairments in Schizophrenia

noreply@blogger.com (Anonymous) — Thu, 28 Feb 2013 21:34:00 +0000

A study of eye movements in schizophrenia patients provides new evidence of impaired reading fluency in individuals with the mental illness.

The findings, by researchers at McGill University in Montreal, could open avenues to earlier detection and intervention for people with the illness.

While schizophrenia patients are known to have abnormalities in language and in eye movements, until recently reading ability was believed to be unaffected. That is because most previous studies examined reading in schizophrenia using single-word reading tests, the McGill researchers conclude. Such tests aren't sensitive to problems in reading fluency, which is affected by the context in which words appear and by eye movements that shift attention from one word to the next.

The McGill study, led by Ph.D. candidate Veronica Whitford and psychology professors Debra Titone and Gillian A. O'Driscoll, monitored how people move their eyes as they read simple sentences. The results, which were first published online last year, appear in the February issue of the Journal of Experimental Psychology: General.

eye movement measures provide clear and objective indicators of how hard people are working as they read. For example, when struggling with a difficult sentence, people generally make smaller eye movements, spend more time looking at each word, and spend more time re-reading words. They also have more difficulty attending to upcoming words, so they plan their eye movements less efficiently.

The McGill study, which involved 20 schizophrenia outpatients and 16 non-psychiatric participants, showed that reading patterns in people with schizophrenia differed in several important ways from healthy participants matched for gender, age, and family social status. People with schizophrenia read more slowly, generated smaller eye movements, spent more time processing individual words, and spent more time re-reading. In addition, people with schizophrenia were less efficient at processing upcoming words to facilitate reading.

The researchers evaluated factors that could contribute to the problems in reading fluency among the schizophrenia outpatients -- specifically, their ability to parse words into sound components and their ability to skillfully control eye movements in non-reading contexts. Both factors were found to contribute to the reading deficits.

"Our findings suggest that measures of reading difficulty, combined with other information such as family history, may help detect people in the early stages of schizophrenia -- and thereby enable earlier intervention," Whitford says.

Moreover, fluent reading is a crucial life skill, and in people with schizophrenia, there is a strong relationship between reading skill and the extent to which they can function independently, the researchers note. "Improving reading through intervention in people with schizophrenia may be important to improving their ability to function in society," Titone adds.

Article republished from http://www.sciencedaily.com/releases/2013/02/130219121451.htm

Vitreous Detachment

noreply@blogger.com (Anonymous) — Wed, 13 Feb 2013 19:32:00 +0000

What is vitreous detachment?

Most of the eye's interior is filled with vitreous, a gel-like substance that helps the eye maintain a round shape. There are millions of fine fibers intertwined within the vitreous that are attached to the surface of the retina, the eye's light-sensitive tissue. As we age, the vitreous slowly shrinks, and these fine fibers pull on the retinal surface. Usually the fibers break, allowing the vitreous to separate and shrink from the retina. This is avitreous detachment.
In most cases, a vitreous detachment, also known as a posterior vitreous detachment, is not sight-threatening and requires no treatment.

Risk Factors

Who is at risk for vitreous detachment?

A vitreous detachment is a common condition that usually affects people over age 50, and is very common after age 80. People who are nearsighted are also at increased risk. Those who have a vitreous detachment in one eye are likely to have one in the other, although it may not happen until years later.

Symptoms and Detection

What are the symptoms of vitreous detachment?

As the vitreous shrinks, it becomes somewhat stringy, and the strands can cast tiny shadows on the retina that you may notice as floaters, which appear as little "cobwebs" or specks that seem to float about in your field of vision. If you try to look at these shadows they appear to quickly dart out of the way.
One symptom of a vitreous detachment is a small but sudden increase in the number of new floaters. This increase in floaters may be accompanied by flashes of light (lightning streaks) in your peripheral, or side, vision. In most cases, either you will not notice a vitreous detachment, or you will find it merely annoying because of the increase in floaters.

How is vitreous detachment detected?

The only way to diagnose the cause of the problem is by a comprehensive dilated eye examination. If the vitreous detachment has led to a macular hole or detached retina, early treatment can help prevent loss of vision.

Treatment

How does vitreous detachment affect vision?

Although a vitreous detachment does not threaten sight, once in a while some of the vitreous fibers pull so hard on the retina that they create amacular hole to or lead to a retinal detachment. Both of these conditions are sight-threatening and should be treated immediately.
If left untreated, a macular hole or detached retina can lead to permanent vision loss in the affected eye. Those who experience a sudden increase in floaters or an increase in flashes of light in peripheral vision should have an eye care professional examine their eyes as soon as possible.
Article republished from http://www.nei.nih.gov/health/vitreous/vitreous.asp#a

Who is likely to develop Dry Eye?

noreply@blogger.com (Anonymous) — Wed, 30 Jan 2013 15:26:00 +0000

Who is likely to develop Dry Eye?

Elderly people frequently experience dryness of the eyes, but Dry Eye can occur at any age. Nearly five million Americans 50 years of age and older are estimated to have Dry Eye. Of these, more than three million are women and more than one and a half million are men. Tens of millions more have less severe symptoms. Dry Eye is more common after menopause. Women who experience menopause prematurely are more likely to have eye surface damage from Dry Eye.

Treatment

How is Dry Eye treated?

Depending on the causes of Dry Eye, your doctor may use various approaches to relieve the symptoms.

Dry Eye can be managed as an ongoing condition. The first priority is to determine if a disease is the underlying cause of the Dry Eye (such as Sjögren's syndrome or lacrimal and meibomian gland dysfunction). If it is, then the underlying disease needs to be treated.

Cyclosporine, an anti-inflammatory medication, is the only prescription drug available to treat Dry Eye. It decreases corneal damage, increases basic tear production, and reduces symptoms of Dry Eye. It may take three to six months of twice-a-day dosages for the medication to work. In some cases of severe Dry Eye, short term use of corticosteroid eye drops that decrease inflammation is required.

If Dry Eye results from taking a medication, your doctor may recommend switching to a medication that does not cause the Dry Eye side effect.

If contact lens wear is the problem, your eye care practitioner may recommend another type of lens or reducing the number of hours you wear your lenses. In the case of severe Dry Eye, your eye care professional may advise you not to wear contact lenses at all.

Another option is to plug the drainage holes, small circular openings at the inner corners of the eyelids where tears drain from the eye into the nose. Lacrimal plugs, also called punctal plugs, can be inserted painlessly by an eye care professional. The patient usually does not feel them. These plugs are made of silicone or collagen, are reversible, and are a temporary measure. In severe cases, permanent plugs may be considered.

In some cases, a simple surgery, called punctal cautery, is recommended to permanently close the drainage holes. The procedure helps keep the limited volume of tears on the eye for a longer period of time.

In some patients with Dry Eye, supplements or dietary sources (such as tuna fish) of omega-3 fatty acids (especially DHA and EPA) may decrease symptoms of irritation. The use and dosage of nutritional supplements and vitamins should be discussed with your primary medical doctor.

What can I do to help myself?

Use artificial tears, gels, gel inserts, and ointments - available over the counter - as the first line of therapy. They offer temporary relief and provide an important replacement of naturally produced tears in patients with aqueous tear deficiency. Avoid artificial tears with preservatives if you need to apply them more than four times a day or preparations with chemicals that cause blood vessels to constrict.
Wearing glasses or sunglasses that fit close to the face (wrap around shades) or that have side shields can help slow tear evaporation from the eye surfaces. Indoors, an air cleaner to filter dust and other particles helps prevent Dry Eyes. A humidifier also may help by adding moisture to the air.
Avoid dry conditions and allow your eyes to rest when performing activities that require you to use your eyes for long periods of time. Instill lubricating eye drops while performing these tasks.

Article republished from: http://www.nei.nih.gov/health/dryeye/dryeye.asp

Conjunctivitis: Do antibiotics help?

noreply@blogger.com (Anonymous) — Sat, 22 Dec 2012 05:32:00 +0000

In more than half of all people who have conjunctivitis, the infection goes away without treatment within a week. Antibiotic eye drops or ointment can speed up recovery. Adverse effects are very rare.

Conjunctivitis makes people’s eyes red and inflamed. It often affects both eyes because the infection can easily spread from one eye to the other. Your eyes get watery and produce a yellowish-white discharge that makes your eyelids stick together. They may become very sore too. Conjunctivitis is contagious but often gets better within a week, even without any treatment. So it is often enough to simply wait.

Conjunctivitis is usually caused by bacteria or viruses. Because conjunctivitis usually goes away so quickly, though, it is generally not worth doing tests to find out if it is a bacterial or viral infection. Doctors often prescribe antibiotics just in case, in the form of eye drops or ointments. Antibiotics only work against bacteria, though, and not against viruses, so they are not always effective.

Some people use non-antibiotic eye drops. The use of cold or warm compresses is common too. But there is not enough research on these approaches to be able to say whether they have a benefit, no effect, or are possibly even harmful. Sometimes conjunctivitis is linked to an allergy. Then it is treated with allergy medicines like antihistamines.

Research on antibiotics in the treatment of conjunctivitis

Two groups of researchers from the Cochrane Collaboration (an international network of researchers) and from various universities in England, the Netherlands and Australia analyzed the results of trials on the treatment of conjunctivitis with antibiotics. They wanted to find out whether antibiotics help in the treatment of ordinary conjunctivitis, as well as which possible disadvantages they have.

The researchers only analyzed the results of studies that compared at least two groups of people. One group of people used antibiotic eye drops or ointments. The other group used non-antibiotic eye drops or ointments, or did not have any treatment at first. The researchers were only interested in studies in which the participants were randomly assigned to one of the treatment groups. This kind of study, called a randomized controlled trial, delivers the most reliable results. Read our information "Evidence-based medicine" to find out more about how good-quality trials are carried out.

The researchers found 12 trials, involving a total of about 4,000 people with conjunctivitis. Both children and adults participated in the trials.

Antibiotics can speed up recovery

Overall, the analysis of the trial results showed that conjunctivitis goes away somewhat faster if antibiotics are used. This is what was found for people who went to see their family doctor because they had conjunctivitis:

The infection cleared up within one week in 71 out of 100 people who did not use antibiotics.
The infection cleared up within that same amount of time in 80 out of 100 people who used antibiotics.

In other words, antibiotics were found to speed up recovery in 9 out of 100 people.

In studies that were carried out in a specialist practice, it took a little longer for the infection to clear up – both in the people who used antibiotics and in those who did not use antibiotics. One possible explanation for this is that people who go to see a specialist doctor probably have more severe cases of conjunctivitis. But the antibiotics had a similar beneficial effect to that found in the family doctor trials.

None of the trials reported that antibiotics had adverse effects. The trials did not look into whether antibiotics helped lower the risk of the infection spreading.

Recognizing signs of complications and avoiding the spread of infection

As already mentioned, conjunctivitis usually goes away without treatment. But some symptoms could be signs of more serious problems. These symptoms include worsening vision, increased sensitivity to light, the feeling that you have something in your eye, and a severe headache together with nausea. It is important to see a doctor if you have any of these symptoms.

In people who wear contact lenses, the infection can spread to the cornea (the clear surface of the eye itself). Inflammation of the cornea, also known as keratitis, is not common though: it is estimated that conjunctivitis leads to keratitis in about 3 out of every 10,000 contact lens wearers. In the trials that the researchers included in their analysis, none of the participants developed keratitis.

If conjunctivitis is caused by viruses it can be highly contagious and hard to get rid of. But there are several things that can be done to try to stop viral infections from spreading. Because the virus is easily spread through finger contact, it is important to avoid touching your eyes with your hands, and to wash your hands if you do accidentally touch your eyes. It is also a good idea to have your own towels and washcloths, and not to share them with other people. Another important way to protect others from infection is by not shaking hands with them and not touching their face.

Original Article found at http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0005040/

Published by the Institute for Quality and Efficiency in Health Care (IQWiG)Next planned update:
October 2015. You can find out more about how our health information is updated in our text "Informed Health Online: How our information is produced".

References

IQWiG health information is based on research in the international literature. We identify the most scientifically reliable knowledge currently available, particularly what are known as “systematic reviews”. These summarize and analyze the results of scientific research on the benefits and harms of treatments and other health care interventions. This helps medical professionals and people who are affected by the medical condition to weigh up the pros and cons. You can read more about systematic reviews and why these can provide the most trustworthy evidence about the state of knowledge in our information "Evidence-based medicine". We also have our health information reviewed to ensure medical and scientific accuracy.
Jefferis J, Perera R, Everitt H, van Weert H, Rietveld R, Glasziou P et al. Acute infective conjunctivitis in primary care: who needs antibiotics? An individual patient data meta-analysis. Br J Gen Pract 2011; 61(590): e542-548. [Full text]
Sheikh A, Hurwitz B, van Schayck CP, McLean S, Nurmatov U. Antibiotics versus placebo for acute bacterial conjunctivitis. Cochrane Database Syst Rev 2012; (9): CD001211. [Summary]

What is a Cataract?

noreply@blogger.com (Anonymous) — Wed, 31 Oct 2012 03:25:00 +0000

Cataract Defined

What is a Cataract?

A Cataract is a clouding of the lens in the eye that affects vision. Most Cataracts are related to aging. Cataracts are very common in older people. By age 80, more than half of all Americans either have a Cataract or have had Cataract surgery.

A Cataract can occur in either or both eyes. It cannot spread from one eye to the other.

What is the lens?

The lens is a clear part of the eye that helps to focus light, or an image, on the retina. The retina is the light-sensitive tissue at the back of the eye.

In a normal eye, light passes through the transparent lens to the retina. Once it reaches the retina, light is changed into nerve signals that are sent to the brain.

The lens must be clear for the retina to receive a sharp image. If the lens is cloudy from a Cataract, the image you see will be blurred.

Are there other types of Cataract?

Yes. Although most Cataracts are related to aging, there are other types of Cataract:

Secondary Cataract. Cataracts can form after surgery for other eye problems, such as glaucoma. Cataracts also can develop in people who have other health problems, such as diabetes. Cataracts are sometimes linked to steroid use.
Traumatic Cataract. Cataracts can develop after an eye injury, sometimes years later.
Congenital Cataract. Some babies are born with Cataracts or develop them in childhood, often in both eyes. These Cataracts may be so small that they do not affect vision. If they do, the lenses may need to be removed.
Radiation Cataract. Cataracts can develop after exposure to some types of radiation.

Normal vision

The same scene as viewed by a person with Cataract

What Is Orthokeratology?

noreply@blogger.com (drwrigley) — Mon, 22 Oct 2012 15:42:00 +0000

What Is Orthokeratology?

In the most basic of terms Accelerated Overnight Orthokeratology or Ortho-k is the science of changing the curvature or shape of the cornea to change how light is focused on the retina at the back of one's eye.

Think of the cornea as the eye's equivalent of a watch crystal. It is a clear, dome shaped structure that overlies the colored iris. Its tissue is most similar to clear, wet skin; and like skin it is very pliable. Because the cornea separates the eye from air and the rest of the outside world and because it has a curvature that bends light towards the back of the eye, it is responsible for most of the eye's corrective power and contributes to various conditions such as nearsightedness (myopia), farsightedness (hyperopia), and the blur of astigmatism.

When you choose Ortho-k a few key tests must be performed. Chief among these tests is the determination that your eyes are healthy. The Orthokeratologist will examine the retina and also the health of the outside of the eye. The other key procedure is the mapping of your cornea. To do this an instrument called a Topographer is used. Just like a topographical map of a camping area show hills, plains, and valleys; the topography of the eye shows your doctor exactly how your cornea is shaped. The information from your corneal mapping plus the size of your cornea and the prescription needed to correct your vision are all used to design the retainer lenses (corneal molds) needed to create the Ortho-k effect.

On the day you pick up your Ortho-k retainer lenses you will be instructed in how to insert, remove, and take care your vision retainers. The fit of your retainers will be evaluated and you will be scheduled to be seen after your first night of wear. On day 1, your doctor will re-evaluate your fit and newly corrected vision and another mapping of your cornea will be performed.

Throughout your initial fitting period, your Orthokeratologist will monitor your corneal health and the effectiveness of treatment. At certain times your retainer lens fit may be modified to achieve your goals.

Orthokeratology can produce results in a surprisingly short period of time. The length of treatment to achieve your goals can vary from patient to patient. Factors which can affect the speed of treatment include:

your initial prescription
corneal rigidity
tear quality and quantity
your expectations.

We advise patients that they may need to use their retainers every night to maintain their newly corrected vision although some patients are able to vary their wearing time to once every two to four nights. The reason for this is due to the flexibility of your cornea.

noreply@blogger.com (drwrigley) — Fri, 06 Jul 2012 19:58:00 +0000

Study Links Genes to Common Forms of Glaucoma

ScienceDaily (Apr. 26, 2012) - Results from the largest genetic study of glaucoma, a leading cause of blindness and vision loss worldwide, showed that two genetic variations are associated with primary open angle glaucoma (POAG), a common form of the disease. The identification of genes responsible for this disease is the first step toward the development of gene-based disease detection and treatment.

About 2.2 million people in the U.S. have glaucoma. POAG is often associated with increased eye pressure but about one-third of patients have normal pressure glaucoma (NPG). Currently, no curative treatments exist for NPG.

Researchers including lead author Janey Wiggs, M.D., Ph.D., and Lou Pasquale, M.D., Co-Directors of the Harvard Glaucoma Center of Excellence, analyzed DNA sequences of 6,633 participants, half of whom had POAG. Participants were part of two NIH-funded studies: GLAUGEN (GlAUcoma Genes and Environment) and NEIGHBOR (NEI Glaucoma Human genetics collaBORation), conducted at 12 sites in the United States. Dr. Pasquale is Director of the Glaucoma Service at Mass. Eye and Ear.

The results, reported online in PLoS Genetics (April 26, 2012), found that two variations were associated with POAG, including NPG. These are the first variants commonly associated with NPG. One variant is in a gene located on chromosome 9 called CDKN2BAS whereas the other variant is in a region of chromosome 8 where it may affect the expression of genes LRP12 or ZFPM2. These genes may interact with transforming growth factor beta (TGF-beta), a molecule that regulates cell growth and survival throughout the body. Previous studies have also implicated TGF-beta in glaucoma.

"This research has provided important new insights into the disease pathogenesis and will make future studies focused on translating this information into the clinic possible. Ultimately we hope to prevent blindness caused by this very common eye disease," said lead author Dr. Wiggs.

"This study has identified an important molecular pathway in the development of POAG. Control of TGF-beta might lead to more effective therapies for this blinding disease," said Dr. Hemin Chin, associate director for Ophthalmic Genetics at the National Eye Institute.

Funding sources for this research include the National Eye Institute, National Human Genome Research Institute, Lions Eye Research Fund, Glaucoma Center of Excellence, the Margolis Fund, and Research To Prevent Blindness.

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Future Treatment for Nearsightedness - Compact Fluorescent Light Bulbs?

noreply@blogger.com (drwrigley) — Wed, 06 Jun 2012 17:08:00 +0000

Future Treatment for Nearsightedlness - Compact Fluorescent Light Bulbs?

ScienceDaily (May 8, 2012) - Researchers at the University of Alabama at Birmingham hope to one day use fluorescent light bulbs to slow Nearsightedlness, which affects 40 percent of American adults and can cause blindness.

In an early step in that direction, results of a study found that small increases in daily artificial light slowed the development of Nearsightedlness by 40 percent in tree shrews, which are close relatives of primates.

The team, led by Thomas Norton, Ph.D., professor in the UAB Department of Vision Sciences, presented the study results May 8 at the 2012 Association for Research in Vision and Ophthalmology annual meeting in Ft. Lauderdale.

People can see clearly because the front part of the eye bends light and focuses it on the retina in back. Nearsightedlness, also called myopia, occurs when the physical length of the eye is too long, causing light to focus in front of the retina and blurring images.

Myopia has many causes, some related to inheritance and some to the environment. Research in recent years had, for instance, suggested that children who spent more time outdoors, presumably in brighter outdoor light, had less myopia as young adults. That raised the question of whether artificial light, like sunlight, could help reduce myopia development, without the risks of prolonged sun exposure, such as skin cancer and cataracts.

"Our hope is to develop programs that reduce the rate of myopia using energy efficient, fluorescent lights for a few hours each day in homes or classrooms," said John Siegwart, Ph.D., research assistant professor in UAB Vision Sciences and co-author of the study. "Trying to prevent myopia by fixing defective genes through gene therapy or using a drug is a multi-year, multimillion-dollar effort with no guarantee of success. We hope to make a difference just with light bulbs."

Sorting through theories

Work over 25 years had shown that putting a goggle over one eye of a study animal, one that lets in light but blurs images, causes the eye to grow too long, which in turn causes myopia. Other past studies had shown that elevated light levels could reduce myopia under these conditions, whether the light was produced by halogen lamps, metal halide bulbs or daylight. The current study is the first to show that the development of myopia can be slowed by increasing daily fluorescent light levels.

One prevailing theory on myopia-related shape changes in the eye is that they are caused by the blurriness of images experienced while reading or doing other near-work chores. Another holds some people develop myopia because they have low levels of vitamin D, which goes up with exposure to sunlight and could explain the connection between outdoor light and reduced myopia. A third theory, one reinforced by the current results, is that bright light causes an increase in levels of dopamine, a signaling molecule in the retina.

To test the theories, the team used a goggle that lets in light but no images to produce myopia in one eye of each tree shrew. They found that a group exposed to elevated fluorescent light levels for eight hours per day developed 47 percent less myopia than a control group exposed to normal indoor lighting, even though the images were neither more nor less blurry. They also found that animals fed vitamin D supplements developed myopia just like ones without the supplement. Given these results, the team is now experimenting with light levels and treatment times to see if a short, bright light treatment could be effective. They have also begun studies looking at the effect of elevated light on retinal dopamine levels as it relates to the reduction of myopia.

"If we can find the best kind of light, treatment period and light level, we'll have the scientific justification to begin studies raising light levels in schools, for instance," said Norton. "Compact fluorescent bulbs use much less electricity than standard light bulbs, and future programs raising light levels will have more impact the less expensive they are."

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New Eye Imaging Techniques Are On the Horizon

noreply@blogger.com (drwrigley) — Wed, 23 May 2012 17:44:00 +0000

New Eye Imaging Techniques Are On the Horizon

ScienceDaily (May 7, 2012) - The same technology used by astronomers to obtain clear views of distant stars is now being used by optometrists to perform incredibly detailed examinations of the living Eye.

An update on new developments in ocular imaging techniques -- and how they may affect clinical vision care in the not-too-distant future -- is presented in an article titled "Adaptive Optics Scanning Laser Ophthalmoscope-based Microperimetry" published in a special May issue of Optometry and Vision Science, official journal of the American Academy of Optometry.

Cutting-edge techniques now allow researchers to visualize the fine structure of the Eye in a way that was "not conceivable 20 years ago," according to a guest editorial by Scott Read OD PhD FAAO (Candidate) and colleagues. "As these advanced imaging methods continue to develop, the potential for imaging ocular structures down to the cellular level in everyday clinical practice has become a reality -- and the potential to improve patient care is truly stunning," Dr Read and coauthors add.

New Techniques Provide Cellular-Level Images of the Living Eye The special issue presents 30 reports on the latest, most advanced techniques for imaging and measurement of various Eye structures: the retina and optic nerve, lens and ciliary body, and the anterior Eye. Written by leading researchers and clinicians, the contributions provide a fascinating look at these remarkable new technologies, with a glimpse of their likely extensions into clinical practice.

As just one example, William S. Tuten, OD, MS, and colleagues of the University of California, Berkeley, report on the development and use of an "adaptive optics scanning laser ophthalmoscope." Adaptive optics refers to the use of advanced techniques to correct for optical aberrations through any transparent media. Originally developed for use in telescopes to correct for the distorting effects of the atmosphere, adaptive optics is now being applied to evaluating the structure and function of the human Eye.

Dr. Tuten and colleagues have applied adaptive optics to perimetry -- also known as visual field testing -- on the microscopic scale. Perimetry is an important part of evaluation for patients with vision disorders including macular degeneration, retinitis pigmentosa, and diabetic retinopathy. Perimetry measures vision in all parts of the visual field, including the peripheral vision.

Promising Applications to Improve Clinical Vision Care The new paper describes (and illustrates) the use of adaptive optics-guided microperimtery to assess visual fields at an unprecedented level of detail. The technique can not only show limitations in visual fields, but can trace the defect to individual retinal photoreceptor cells. High-speed tracking is used to correct for normal Eye movement, or "jitter," that is practically undetectable using conventional imaging techniques.

In addition, by using microscopic blood vessels as anatomical landmarks, the adaptive optics technique permits repeated studies to be repeated over time at a high level of precision. This offers unique opportunities for studying how treatments work on the cellular level, as well as following the effects of treatment over time in individual patients.

"This technique opens new horizons for clinician-scientists, and later clinicians, to better understand, and plot out, the relationships between vision and the retinal photoreceptors at a microscopic level," comments Anthony Adams, OD, PhD, Editor-in-Chief of Optometry and Vision Science. "It enables a new understanding of vision loss in patients with retinal disorders where there are discrete photoreceptor losses -- for example, macular degeneration."

Adaptive optics-guided microperimetery and other advanced imaging technologies described in the special issue have the potential to revolutionize the management of eye diseases, Dr. Read and colleagues believe. They conclude, "With ongoing improvements in imaging speed and resolution, and with the application of innovative methods to improve the clinical usefulness of ocular imaging techniques, the future of ocular imaging is bright!"

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noreply@blogger.com (drwrigley) — Fri, 18 May 2012 21:35:00 +0000

Women Have Bigger Pupils Than Men

ScienceDaily (Apr. 26, 2012) - From an anatomical point of view, a normal, non-pathological eye is known as an emmetropic eye, and has been studied very little until now in comparison with myopic and hypermetropic eyes. The results show that healthy emmetropic women have a wider Pupil diameter than men.

Normal, non-pathological emmetropic eyes are the most common type amongst the population (43.2%), with a percentage that swings between 60.6% in children from three to eight years and 29% in those older than 66.

Therefore, a study determines their anatomical pattern so that they serve as a model for comparison with eyes that have refractive defects (myopia, hypermetropia and stigmatism) pathological eyes (such as those that have cataracts).

"We know very little about emmetropic eyes even though they should be used for comparisons with myopic and hypermetropic eyes" Juan Alberto Sanchis-Gimeno, researcher at the University of Valencia and lead author of the study explained.

The project, published in the journal 'Surgical and Radiologic Anatomy' shows the values by gender for the central corneal thickness, minimum total corneal thickness, white to white distance and Pupil diameter in a sample of 379 emmetropic subjects.

"It is the first study that analyses these anatomical indexes in a large sample of healthy emmetropic subjects" Sanchis-Gimeno states. In recent years new technologies have been developed, such as corneal elevation topography, which allows us to increase our understanding of in vivo ocular anatomy.

Although the research states that there are no big differences between most of the parameters analysed, healthy emmetropic women have a wider Pupil diameter than men.

"It will be necessary to investigate as to whether there are differences in the anatomical indexes studied between emmetropic, myopic and hypermetropic eyes, and between populations of different ethnic origin" the researcher concludes.

How the human eye works

Light penetrates through the Pupil, crosses the crystalline lens and is projected onto the retina, where the photoreceptor cells turn it into nerve impulses, and it is transferred through the optic nerve to the brain. Rays of light should refract so that they can penetrate the eye and can be focused on the retina. Most of the refraction occurs in the cornea, which has a fixed curvature.

The Pupil is a dilatable and contractile opening that regulates the amount of light that reaches the retina. The size of the Pupil is controlled by two muscles: the Pupillary sphincter, which closes it, and the Pupillary dilator, which opens it. Its diameter is between 3 and 4.5 millimetres in the human eye, although in the dark it could reach up to between 5 and 9 millimetres.

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noreply@blogger.com (drwrigley) — Fri, 11 May 2012 11:31:00 +0000

New Glaucoma Test Allows Earlier, More Accurate Detection

Cumbersome Glaucoma tests that require a visit to the ophthalmologist could soon be history thanks to a home test developed by a UA engineer.

Phoenix ophthalmologist Dr. Gholan Peyman demonstrates a prototype Glaucoma test instrument that's noninvasive and simpler to use than current procedures. It can also be used in situations that are difficult or impossible with current tests. (Credit: Image courtesy of University of Arizona College of Engineering)

The self-test instrument has been designed in Eniko Enikov's lab at the UA College of Engineering. Gone are the eye drops and need for a sterilized sensor. In their place is an easy-to-use probe that gently rubs the eyelid and can be used at home.

"You simply close your eye and rub the eyelid like you might casually rub your eye," said Enikov, a professor of aerospace and mechanical engineering. "The instrument detects the stiffness and, therefore, infers the intraocular pressure." Enikov also heads the Advanced Micro and Nanosystems Laboratory.

While the probe is simple to use, the technology behind it is complex, involving a system of micro-force sensors, specially designed microchips, and math-based procedures programmed into its memory.

Enikov began working on the probe four years ago in collaboration with Dr. Gholan Peyman, a Phoenix ophthalmologist. "We went through several years of refinement and modifications to arrive at the current design," Enikov noted.

The National Science Foundation has funded the work, and Enikov and Peyman now are seeking investors to help fund final development and commercialization of the product.

In addition to screening for Glaucoma, an eye disease that can lead to blindness if left untreated, the device corrects some problems with the current procedure, and can be used to measure drainage of intraocular fluid.

"Eye pressure varies over a 24-hour cycle," Enikov said. "So it could be low at the doctor's office and three hours later it might be high. With only a single test, the doctor might miss the problem. Having the ability to take more frequent tests can lead to earlier detection in some cases."

Once the diagnosis is made, several treatments are available. The question then is: How effective are they? Patients could use the probe at home to trace how much the pressure decreases after using eye drop medications, for instance.

"One of the reasons pressure builds up in the eye is because fluid doesn't drain properly," Enikov noted. "Currently, there are no methods available to test drainage."

Current tests require applying pressure directly to the cornea, but only very light pressure is safe to use, and it doesn't cause the fluid to drain.

"Our technique allows us to apply slightly greater pressure, but it's still not uncomfortable," he said. "It's equivalent to rubbing your eye for a brief period to find out if the pressure changes. If it does, we know by how much and if there is a proper outflow of intraocular fluid."

Sometimes, a surgical shunt is used to help fluid drain from the eye. "The problem with Glaucoma shunts is they can plug up over time," Enikov noted. "Or if they're not properly installed, they may drain too quickly. So you would want to know how well the shunt is working and if it is properly installed. Our device could help answer those questions."

In another scenario, certain patients cannot be tested for Glaucoma using currently available procedures. "If a patient had cataract surgery or some other surgery through the cornea, the cornea sometimes thickens," Enikov said. "The cornea's structure is different, but our test remains accurate because it's not applied to the cornea."

Instead, it presses the entire eyeball, much as you might press a balloon to determine its stiffness.

"The innovation with our device is that it's noninvasive, simpler to use and applies to a variety of situations that are either difficult to address or impossible to test using the current procedures," Enikov said. "That's why we're so excited about this probe. It has great potential to improve medical care, and significant commercial possibilities, as well."

http://www.sciencedaily.com/releases/2011/01/110104101331.htm

The above story is reprinted from materials provided by University of Arizona College of Engineering. The original article was written by Ed Stiles.
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Vitamin B-Based Treatment for Corneal Disease May Offer Some Patients a Permanent Solution

noreply@blogger.com (drwrigley) — Wed, 25 Apr 2012 15:16:00 +0000

Vitamin B-Based Treatment for Corneal Disease May Offer Some Patients a Permanent Solution

ScienceDaily (Oct. 24, 2011) - Patients in the United States who have the Cornea-damaging disease keratoconus may soon be able to benefit from a new treatment that is already proving effective in Europe and other parts of the world. The treatment, called collagen crosslinking, improved vision in almost 70 percent of patients treated for keratoconus in a recent three-year clinical trial in Milan, Italy. The treatment is in clinical trials in the United States and is likely to receive FDA approval in 2012.

The results of the Milan study are being presented Oct. 24, 2011 at the 115th Annual Meeting of the American Academy of Ophthalmology in Orlando, Florida.

In a session titled Long-term Results of Corneal Crosslinking for Keratoconus, Paolo Vinciguerra, MD will describe the treatment and three-year follow up of more than 250 keratoconus patients who received collagen crosslinking at his clinic. Sixty-eight percent of the 500 eyes treated gained significant visual acuity, with their results remaining stable at the end of the follow-up period. Patients over age 18 were most likely to improve.

In the collagen crosslinking procedure, riboflavin (vitamin B) is applied to the Cornea, which is then exposed to a specific form of ultraviolet light. Collagen fibers regenerate with new bonds forming between them, increasing Corneal stiffness and strength. The treatment also combats the causes of keratoconus, reducing the chance that it will recur. The rest of the eye receives only minimal UV exposure during treatment. Dr. Vinciguerra's new study confirms that adverse effects are rare. Previous research by his team indicated no loss of Corneal endothelial cell, a measurement used to assess the safety of corneal treatments, in patients who received collagen crosslinking.

"For many people with keratoconus, collagen crosslinking can provide a better and more permanent solution to their vision problems," said Dr. Vinciguerra. "Given that no current treatment in use in the U.S. offers permanent correction, this effective option represents a significant advance for corneal medicine."

One in 2,000 people in the United States and worldwide are diagnosed with keratoconus, a disease that damages the collagen fibers that form the structure of the cornea, which is the outer surface of the eye. The cornea's crucial task is to focus, or "refract," incoming light toward the eye's lens. To perform properly, the cornea needs to be rounded, like the surface of a ball. As keratoconus worsens and the cornea becomes thinner, it may bulge outward in a cone shape, causing nearsightedness and/or astigmatism, making clear vision impossible. As the number of fibers and links between them decline, the cornea loses up to 50 percent of its normal stiffness.

Standard treatments in the U.S., such as specialized eyeglasses, contact lenses, or implanted lenses, cannot permanently correct keratoconus, and none of these treatments address the underlying causes. Severe keratoconus often requires corneal transplant.

The 115th Annual Meeting of the American Academy of Ophthalmology is in session October 23 through 25 at the Orange County Convention Center in Orlando, Fla. It is the world's largest, most comprehensive ophthalmic education conference. Approximately 25,000 attendees and more than 500 companies gather each year to showcase the latest in ophthalmic technology, products and services. To learn more about the place Where All of Ophthalmology Meets visit www.aao.org/annual_meeting.

http://www.sciencedaily.com/releases/2011/10/111024084641.htm

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Vitamin D Could Help Combat the Effects of Aging in Eyes

noreply@blogger.com (drwrigley) — Sat, 21 Apr 2012 22:16:00 +0000

Vitamin D Could Help Combat the Effects of Aging in Eyes

ScienceDaily (Jan. 17, 2012) — Researchers funded by the Biotechnology and Biological Sciences Research Council (BBSRC) have found that vitamin D reduces the effects of aging in mouse Eyes and improves the vision of older mice significantly. The researchers hope that this might mean that vitamin D supplements could provide a simple and effective way to combat age-related eye diseases, such as macular degeneration (AMD), in people.

The research was carried out by a team from the Institute of Ophthalmology at University College London and is published in the current issue of the journal Neurobiology of Ageing.
Professor Glen Jeffery, who led the work, explains "In the back of the Eyes of mammals, like mice and humans, is a layer of tissue called the retina. Cells in the retina detect light as it comes into the Eyes and then send messages to the brain, which is how we see. This is a demanding job, and the retina actually requires proportionally more energy than any other tissue in the body, so it has to have a good supply of blood. However, with aging the high energy demand produces debris and there is progressive inflammation even in normal animals. In humans this can result in a decline of up to 30% in the numbers of light receptive cells in the eye by the time we are 70 and so lead to poorer vision."
The researchers found that when old mice were given vitamin D for just six weeks, inflammation was reduced, the debris partially removed, and tests showed that their vision was improved.
The researchers identified two changes taking place in the Eyes of the mice that they think accounted for this improvement. Firstly, the number of potentially damaging cells, called macrophages, were reduced considerably in the Eyes of the mice given vitamin D. Macrophages are an important component of our immune systems where they work to fight off infections. However in combating threats to the aged body they can sometimes bring about damage and inflammation. Giving mice vitamin D not only led to reduced numbers of macrophages in the eye, but also triggered the remaining macrophages to change to a different configuration. Rather than damaging the eye the researchers think that in their new configuration macrophages actively worked to reduce inflammation and clear up debris.
The second change the researchers saw in the Eyes of mice given vitamin D was a reduction in deposits of a toxic molecule called amyloid beta that accumulates with age. Inflammation and the accumulation of amyloid beta are known to contribute, in humans, to an increased risk of age-related macular degeneration (AMD), the largest cause of blindness in people over 50 in the developed world. The researchers think that, based on their findings in mice, giving vitamin D supplements to people who are at risk of AMD might be a simple way of helping to prevent the disease.
Professor Jeffery said "When we gave older mice the vitamin D we found that deposits of amyloid beta were reduced in their Eyes and the mice showed an associated improvement of vision. People might have heard of amyloid beta as being linked to Alzheimer's disease and new evidence suggests that vitamin D could have a role in reducing its build up in the brain. So, when we saw this effect in the Eyes as well, we immediately wondered where else these deposits might be being reduced."
Professor Jeffery and his team then went on to study some of the blood vessels of their mice. They found that the mice that had been given the vitamin D supplement also had significantly less amyloid beta built up in their blood vessels, including in the aorta.
Professor Jeffery continues "Finding that amyloid deposits were reduced in the blood vessels of mice that had been given vitamin D supplements suggests that vitamin D could be useful in helping to prevent a range of age-related health problems, from deteriorating vision to heart disease."
Professor Jeffery thinks that this link between vitamin D and a range of age-related diseases might be linked to our evolutionary history. For much of human history our ancestors lived in Africa, probably without clothes, and so were exposed to strong sunlight all year round. This would have triggered vitamin D production in the skin. Humans have only moved to less sunny parts of the world and adopted clothing relatively recently and so might not be well adapted to reduced exposure to the sun. Secondly, life expectancy in the developed world has increased greatly over the past few centuries, so reduced exposure to vitamin D is now coupled with exceptionally long lifespan.
Professor Jeffery said "Researchers need to run full clinical trials in humans before we can say confidently that older people should start taking vitamin D supplements, but there is growing evidence that many of us in the Western world are deficient in vitamin D and this could be having significant health implications."
Professor Douglas Kell, BBSRC Chief Executive said "Many people are living to an unprecedented old age in the developed world. All too often though, a long life does not mean a healthy one and the lives of many older people are blighted by ill health as parts of their bodies start to malfunction.
"If we are to have any hope of ensuring that more people can enjoy a healthy, productive retirement then we must learn more about the changes that take place as animals age. This research shows how close study of one part of the body can lead scientists to discover new knowledge that is more widely applicable. By studying the fundamental biology of one organ scientists can begin to draw links between a number of diseases in the hope of developing preventive strategies."
http://www.sciencedaily.com/releases/2012/01/120117145234.htm
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How Does Nearsightedness Develop in Children?

noreply@blogger.com (drwrigley) — Fri, 13 Apr 2012 12:39:00 +0000

How Does Nearsightedness Develop in Children?

ScienceDaily (Mar. 1, 2012) - Myopia (Nearsightedness) develops in children when the lens stops compensating for continued growth of the eye, according to a study in the March issue of Optometry and Vision Science, official journal of the American Academy of Optometry.

The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.

Using detailed information on eye growth and vision changes in children over time, the new research shows "decoupling" of lens adaptation from eye growth about a year before myopia occurs. Donald O. Mutti, OD, PhD, of The Ohio State University College of Optometry, is lead author of the new study.

Growth Imbalance Leads to Myopia…

The researchers analyzed repeated measurements of vision and eye growth performed over several years in children aged 6 to 14. The study focused on the growth of the two key parts of the eye affecting normal vision: the cornea, the transparent front part that lets light into the eye; and the lens, located behind the cornea, which focuses light rays on the retina at the back of the eye.

Myopia or Nearsightedness -- difficulty seeing objects at a distance -- develops in about 34% of American children as they grow. Vision professionals and scientists typically think of myopia as a problem occurring when the eyeball becomes too long (front to back) for the optical power of the cornea and lens.

However, it has been unclear how this imbalance develops in children who previously had normal vision. To answer this question, Dr. Mutti and colleagues compared changes in eye growth for children who developed myopia at different ages versus those whose vision remained normal.

They found that, in children without myopia, the lens grew thinner and flatter to maintain normal vision as the eye grew. This adaptation maintained a normal balance between the optical power of the lens and the increasing length of the eyeball. From age nine months to nine years, eyeball length increased by an average of three millimeters.

...As Lens Stops Responding to Increasing Eye Length

However, in children who developed myopia, the lens stopped changing in response to eye growth. Nearsightedness developed not just because of increases in the length of the eyeball, but rather because the optical power of the lens no longer changed as the eye grew.

The imbalance occurred rather suddenly: about one year before the children became Nearsighted. For at least five years after the development of myopia, the eye kept becoming longer but the lens stopped flattening and thinning.

In contrast to the lens, changes in corneal growth showed little or no relation to the development of myopia. The cornea is responsible for about two-thirds of the optical power of the eye, and the lens for the remaining one-third.

The study provides vision professionals with an important new piece of information on why some children develop myopia. However, what's still unclear is why the lens suddenly stops adapting to continued growth of the eye. More research will be needed to answer that question -- one possibility is that an abnormally thick ciliary muscle within the eye forms a mechanical restriction preventing the stretching that thins and flattens the lens as the eye continues to grow.

http://www.sciencedaily.com/releases/2012/03/120301113258.htm

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Glaucoma as Neurologic Disorder Rather Than Eye Disease?

noreply@blogger.com (drwrigley) — Tue, 03 Apr 2012 16:26:00 +0000

Glaucoma as Neurologic Disorder Rather Than Eye Disease?

ScienceDaily (Mar. 7, 2012) - A new paradigm to explain Glaucoma is rapidly emerging, and it is generating brain-based treatment advances that may ultimately vanquish the disease known as the "sneak thief of sight." A review now available in Ophthalmology, the journal of the American Academy of Ophthalmology, reports that some top researchers no longer think of Glaucoma solely as an eye disease. Instead, they view it as a neurologic disorder that causes nerve cells in the brain to degenerate and die, similar to what occurs in Parkinson disease and in Alzheimer's. The review, led by Jeffrey L Goldberg, M.D., Ph.D., assistant professor of ophthalmology at the Bascom Palmer Eye Institute and Interdisciplinary Stem Cell Institute, describes treatment advances that are either being tested in patients or are scheduled to begin clinical trials soon.

Glaucoma is the most common cause of irreversible blindness worldwide. For many years, the prevailing theory was that vision damage in Glaucoma patients was caused by abnormally high pressure inside the eye, known as intraocular pressure (IOP). As a result, lowering IOP was the only goal of those who developed surgical techniques and medications to treat Glaucoma. Creating tests and instruments to measure and track IOP was crucial to that effort. Today, a patient's IOP is no longer the only measurement an ophthalmologist uses to diagnose Glaucoma, although it is still a key part of deciding how to care for the patient. IOP-lowering medications and surgical techniques continue to be effective ways to protect Glaucoma patients' eyes and vision. Tracking changes in IOP over time informs the doctor whether the treatment plan is working.

But even when surgery or medication successfully lowers IOP, vision loss continues in some Glaucoma patients. Also, some patients find it difficult to use eye drop medications as prescribed by their physicians. These significant shortcomings spurred researchers to look beyond IOP as a cause of Glaucoma and focus of treatment.

The new research paradigm focuses on the damage that occurs in a type of nerve cell called retinal ganglion cells (RGCs), which are vital to the ability to see. These cells connect the eye to the brain through the optic nerve.

RGC-targeted Glaucoma treatments now in clinical trials include: medications injected into the eye that deliver survival and growth factors to RGCs; medications known to be useful for stroke and Alzheimer's, such as cytidine-5-diphosphocholine; and electrical stimulation of RGCs, delivered via tiny electrodes implanted in contact lenses or other external devices. Human trials of stem cell therapies are in the planning stages.

"As researchers turn their attention to the mechanisms that cause retinal ganglion cells to degenerate and die, they are discovering ways to protect, enhance and even regenerate these vital cells," said Dr. Goldberg. "Understanding how to prevent damage and improve healthy function in these neurons may ultimately lead to sight-saving treatments for Glaucoma and other degenerative eye diseases."

If this neurologically-based research succeeds, future Glaucoma treatments may not only prevent Glaucoma from stealing patients' eyesight, but may actually restore vision. Scientists also hope that their in-depth exploration of RGCs will help them determine what factors, such as genetics, make some people more vulnerable to Glaucoma.

http://www.sciencedaily.com/releases/2012/03/120307094659.htm

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New Treatment For Age-Related Macular Degeneration Within Sight

noreply@blogger.com (drwrigley) — Wed, 28 Mar 2012 14:12:00 +0000

New Treatment For Age-Related Macular Degeneration Within Sight

With 8 million people at high risk for advanced age-related Macular Degeneration, researchers from Harvard and Japan discovered that the experimental drug, endostatin, may be the cure. A research report describes how giving endostatin to mice significantly reduced or eliminated abnormal blood vessel growth within the eye, which is ultimately why the disease causes blindness.

"Our study provides intriguing findings that may lead to a better treatment of age-related Macular Degeneration," said Alexander Marneros, the first author of the report, "but clinical studies in patients with age-related Macular Degeneration are still necessary."

In this study, researchers describe testing the effects of endostatin on mice lacking this naturally occurring substance. The mice without endostatin were about three times more likely to develop advanced age-related Macular Degeneration (AMD) than normal mice. Then the researchers administered endostatin to both sets of mice. In the mice lacking endostatin, the number of abnormal blood vessels that cause AMD were reduced to normal levels. In control mice with normal levels of endostatin, the number of abnormal blood vessels were practically undetectable.

"With Baby Boomers reaching advanced ages, new treatments are desperately needed to keep age-related Macular Degeneration from becoming a national epidemic," said Gerald Weissmann, MD, Editor-in-Chief of The FASEB Journal. "This research provides hope for those at risk for blindness, and it gives everyone another glimpse of how investments in molecular biology will ultimately pay off in terms of new treatments and cures."

AMD is a progressive disease that affects the part of the eye that allows people to see fine details. The disease gradually destroys sharp, central vision, and in advanced stages ultimately leads to total blindness. Abnormal blood vessel growth, also known as angiogenesis, is a hallmark of advanced AMD. These faulty blood vessels leak fluids and blood, causing catastrophic vision loss.

As the name implies, risk for age-related Macular Degeneration increases with age, and 8 million people are considered to be at high risk for the disease. Of these individuals, approximately 1 to 1.3 million will develop advanced AMD within the next five years. Endostatin is an experimental drug, which is currently being tested to stop cancer in people by restricting the formation of abnormal blood vessels supply blood to tumors. Endostatin is a protein in collagen, and while collagen is used in a range of products for skin care to gelatin desserts, consumption or use of these products does not have any effect on tumors or AMD.

Weissmann added, "This research proves once and for all that endostatin functions as the body's own natural inhibitor of new blood vessel growth as Judah Folkman of Harvard predicted."

This research was published in the December 2007 issue of The FASEB Journal.

http://www.sciencedaily.com/releases/2007/11/071129142449.htm

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Laser's Precision and Simplicity Could Revolutionize Cataract Surgery

noreply@blogger.com (drwrigley) — Tue, 20 Mar 2012 19:32:00 +0000

Laser's Precision and Simplicity Could Revolutionize Cataract Surgery

Two new studies add to the growing body of evidence that a new approach to Cataract surgery may be safer and more efficient than today's standard procedure. The new approach, using a special femtosecond laser, is FDA-approved, but not yet widely available in the United States. It's one of the hottest topics this week at the 115th Annual Meeting of the American Academy of Ophthalmology.

Research reported Oct. 23 by William W. Culbertson, MD, of the Bascom Palmer Eye Institute at the University of Miami School of Medicine, and by Mark Packer, MD, of Oregon Health and Sciences University, confirms several advantages of laser Cataract surgery.

Laser Lens Fragmentation Boost Safety by Reducing Need for Ultrasound

Dr. Culbertson's team studied how pre-treating Cataracts with the femtosecond laser affected the level of ultrasound energy needed to soften the Cataracts. This emulsification is performed so that the Cataracts can be easily suctioned out. Surgeons want to use the lowest possible level of ultrasound energy, since in a small percentage of patients it is associated with slower recovery of good vision after surgery and/or problems with the cornea, which is the clear outer layer of the eye. Ideally, in appropriate cases, ultrasound use would be eliminated altogether.

In Dr. Culbertson's prospective, randomized study, 29 patients had laser Cataract surgery with a femtosecond laser in one eye and the standard Cataract procedure, called phacoemulsification, in the other. Laser surgery included: a laser capsulotomy, which is a circular incision in the lens capsule, followed by laser lens fragmentation, then ultrasound emulsification and aspiration. Lens fragmentation involved using the laser to split the lens into sections and then soften it by etching cross-hatch patterns on its surface. Standard surgery included a manual incision, followed by ultrasound emulsification and aspiration. After Cataract removal by either method, intraocular lenses were inserted into eyes to replace the natural lens and provide appropriate vision correction for each patient.

The use of ultrasound energy use was reduced by 45 percent in the laser pre-treated eyes compared with the eyes that received the standard cataract surgery procedure. Also, surgical manipulation of the eye was reduced by 45 percent in eyes that received laser pre-treatment as compared to manual standard surgery. This study involved the most common types of cataracts, those graded 1- 4. Dr. Culbertson notes that these findings may not apply to higher grade cataracts.

"In clinical practice, surgeons would expect safer, faster cataract surgery when laser pre-treatment is performed before cataract removal," said Dr. Culbertson. "The combination of precision and simplification that is possible with the femtosecond laser represents a major advance for this surgery."

Laser Lens Fragmentation Protects Corneal Endothelial Cells

Dr. Packer's team at the Oregon Health and Sciences University in Portland, Oregon, assessed the safety of laser cataract surgery in terms of loss of corneal endothelial cells, as measured after cataract surgery. Measuring endothelial cell loss is one of the most important ways to assess the safety of new cataract surgery techniques and technology. These cells preserve the cornea's clarity, and since they don't regenerate, they must last a lifetime. Dr. Packer's study found that when laser lens fragmentation was used in 225 eyes, there was no loss of endothelial cells, while the 63 eyes that received standard treatment had cell loss of one to seven percent.

"Our finding, that laser lens fragmentation appears to protect corneal endothelial cells, represents a significant benefit of this new surgery," said Dr. Packer. "This procedure is safer than standard cataract treatment and is likely to mean better vision and fewer eye health concerns for cataract patients, over the long term."

Earlier studies of femtosecond laser cataract surgery found other benefits. The laser allows the surgeon to make smaller, more precise incisions and to perform improved capsulotomies, which is the removal of part of the lens capsule that make intraocular lens (IOL) placement more secure. This reduces the chance that an IOL will later become displaced. Also, laser cataract surgery appears to improve results in patients who opt for advanced technology IOLs, plus corrective corneal incisions, to achieve good all-distance vision.

Femtosecond lasers have been used by ophthalmologists for years in refractive surgery such as LASIK, in-corneal transplants, and in other procedures. In 2009, a new type of femtosecond laser that could reach deep enough into the eye to be used in cataract removal was approved by the FDA. In addition to Dr. Culbertson's and Dr. Packer's presentations, key sessions on the topic at the Academy's 2011 Annual Meeting include a special session in the Sunday afternoon program, Spotlight on Femtosecond-Assisted Cataract Surgery: The Tough Questions, Femtosecond Laser Cataract Surgery: the Future,a video presentation,and two new instruction courses.

http://www.sciencedaily.com/releases/2011/10/111023135653.htm

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Detecting Glaucoma Before It Blinds

noreply@blogger.com (drwrigley) — Wed, 14 Mar 2012 15:36:00 +0000

Detecting Glaucoma Before It Blinds

Early detection and diagnosis of open angle Glaucoma important so that treatment can be used in the early stages of the disease developing to prevent or avoid further vision loss. Writing in a forthcoming issue of the International Journal of Medical Engineering and Informatics, researchers in the US have analyzed and ranked the various risk factors for open angle Glaucoma so that patients can be screened at an earlier stage if they are more likely to develop the condition.

Glaucoma is one of the main leading causes of blindness; it is a progressive and irreversible disease. Of the various forms of Glaucoma, open angle Glaucoma (OAG) is the most common and can cause the most damage. Unfortunately, unless a patient is undergoing regular screening from about the age of 40 years because of a family history, it is otherwise difficult to detect until substantial and irreversible vision loss has occurred. Glaucoma is the third leading cause of blindness worldwide and the second leading cause of blindness in the USA.

Now, Duo Zhou and colleagues at the University of Medicine and Dentistry of New Jersey, Newark, have used statistical collinearity analysis to evaluate risk factors for OAG, and logistic regression models to identify a minimum set of such risk factors for prognosis and diagnosis of the disease. Their study was based on more than 400 patients with subtle or severe vision problems who attended hospital. It reveals the relative risk of being a smoker, age, visual "field test" results, presence of a localized notch or thinning of the neuroretinal rim identified during standard eye examination, cup to disk ratio (a measure of restriction of the optic nerve at the back of the eye) and other factors.

The data are complex and separating out predictors from diagnostic factors was difficult, the team admits. However, they suggest that family history, medical history, current medications, geographic location, visual field test and ocular examination must all be considered in diagnosis and prognosis for OAG. They have excluded certain factors from the OAG prognosis: gender, race, family history of Glaucoma, diabetes mellitus, hypercholesterolemia, thyroid disease, migraine, Reynaud's disease and myopia as these have no direct effect on OAG development.

As revealed in the analyses, the odds of developing OAG will be increased by 91% with an increase in the Cup-to-Disc ratio of 0.1. Risk increases by 3% annually by age but decreases by 31% for every dB increase of mean deviation of Humphrey visual field. The odds of developing OAG will be 4.36 higher for patients with abnormal Humphrey visual filed overall test, 7.19 higher in patients with localized notch or thinning of the neuroretinal rim. Interestingly, patients with a smoking history seem to be less likely to develop OAG as compared to those with smoking history; although there are many smokers with OAG. Oddly, because of the location of the study, the team can also say that patients living in Atlantic/Quebec will be 73% less likely to develop OAG compared to their fellow Canadians in Ontario.

http://www.sciencedaily.com/releases/2011/10/111006094823.htm

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Cornea Gene Discovery Reveals Why Humans See Clearly

noreply@blogger.com (drwrigley) — Tue, 06 Mar 2012 17:16:00 +0000

Cornea Gene Discovery Reveals Why Humans See Clearly

ScienceDaily (Dec. 12, 2011) — A transparent Cornea is essential for vision, which is why the eye has evolved to nourish the Cornea without blood vessels. But for millions of people around the world, diseases of the eye or trauma spur the growth of blood vessels and can cause blindness.

A new Northwestern Medicine study has identified a gene that plays a major role in maintaining clarity of the Cornea in humans and mice -- and could possibly be used as gene therapy to treat diseases that cause blindness. The paper is published in the Proceedings of the National Academy of Sciences.

"We believe we've discovered the master regulator gene that prevents the formation of blood vessels in the eye and protects the clarity of the Cornea," said lead author Tsutomu Kume, associate professor of medicine at Northwestern University Feinberg School of Medicine and a researcher at Feinberg Cardiovascular Research Institute.

The existence of the gene, FoxC1, was previously known, but its role in maintaining a clear Cornea is a new finding. Working with a special breed of mice that are missing this gene, Kume and colleagues found abnormal vascular formations, or blood vessels, streaking their Corneas and blocking light.

When Kume discovered the corneal blood vessels in the mutant mice, he called a collaborator at the University of Alberta in Canada, Ordan Lehmann, MD, professor of ophthalmology and medical genetics.

Lehmann found that his patients who have a single copy of this mutated FoxC1 gene -- and who have congenital glaucoma -- also have abnormal blood vessel growth in their eyes.

"The exciting thing is by showing the loss of FoxC1 causes vascularization of the cornea, it means increasing levels of the gene might help prevent the abnormal growth of blood vessels, potentially in multiple eye disorders that cause blindness," said Lehmann, a coauthor on the paper. "That's the hope." One possible use might be in corneal transplants, he said, where the growth of new blood vessels onto the transplanted cornea is a major problem.

Kume next plans to test the gene therapy in mice to see if injecting FoxC1 inhibits the formation of blood vessels in the cornea.

The research is funded by National Institutes of Health and Canadian Institutes of Health Research.

http://www.sciencedaily.com/releases/2011/12/111212153121.htm

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Contact Lenses Provide Extended Pain Relief to Laser Eye Surgery Patients

noreply@blogger.com (drwrigley) — Thu, 01 Mar 2012 15:17:00 +0000

ContactContact Lenses Provide Extended Pain Relief to Laser Eye Surgery Patients

Scientists are reporting development of ContactContact lenses that could provide a continuous supply of anesthetic medication to the eyes of patients who undergo laser eye surgery -- an advance that could relieve patients of the burden of repeatedly placing drops of medicine into their eyes every few hours for several days.Their report appears in ACS' journal Langmuir

Anuj Chauhan and colleagues explain that more than 1 million laser eye correction procedures are performed each year in the U.S. The surgery enables most patients to see clearly without eye glasses or ContactContact lenses. The procedure known as LASIK is the most common type of laser eye surgery, but complications can develop if the patient undergoes trauma or is hit very hard at any time after the procedure. Photorefractive keratectomy (PRK) doesn't have this complication, and that's why it is preferred for athletes and those in the military. A downside to PRK, however, is a longer period of pain after surgery. To ease their pain, PRK patients place drops of several medications, including anesthetics, into their eyes every few hours, which can interfere with daily life and increase the risk of drug overdose. PRK patients receive a special "bandage ContactContact lens" after surgery to help the outer layer of the eye heal.

The researchers tested whether anesthetics loaded onto this type of lens could release the drugs over time automatically. They found that adding vitamin E to the lenses extended the time of release of three commonly used anesthetics from just under two hours to up to an entire day -- or a few days in some instances. The vitamin E acts as a barrier, keeping the anesthetics on the eye, right where they are needed. The researchers say that, in the future, these lenses could serve as bandage ContactContact lenses after PRK surgery while also delivering necessary pain medications.

The authors acknowledge funding from the University of Florida.

http://www.sciencedaily.com/releases/2012/01/120118112001.htm

The above story is reprinted from materials provided by American Chemical Society.

Note: Materials may be edited for content and length. For further information, please ContactContact the source cited above.

New Light Shed On How Retina's Hardware Is Used in Color Vision

noreply@blogger.com (drwrigley) — Wed, 22 Feb 2012 12:26:00 +0000

New Light Shed On How Retina's Hardware Is Used in Color Vision

Biologists at New York University and the University of Würzburg have identified, in greater detail, how the Retina's cellular hardware is used in color preference. The findings, published in the latest issue of the Proceedings of the National Academy of Sciences (PNAS), enhance our understanding of how eyes and the brain process color.

Light can serve as an attractive or repulsive landmark for orientation -- we identify an object or a light source at a certain location in visual space, then approach it or retreat from it. This process, called phototaxis, was the focus of the PNAS study.

Conducted by biologists at New York University's Center for Developmental Genetics and the Department of Genetics and Neurobiology at the University of Würzburg in Germany, the research specifically examined the photoreceptor cells in the Retinas of the fruit fly Drosophila. Drosophila is a powerful model for studying the color vision process as it is amenable to very specific genetic manipulations, allowing researchers to analyze how its visual system functions when different elements of its Retina are affected.

The visual systems of most species contain photoreceptors with distinct spectral sensitivities that allow animals to distinguish lights by their spectral composition (i.e., color). In Drosophila, six of these (R1-R6) are responsible for motion detection and are sensitive to the brightness or dimness of a broad spectrum of light. Two others (R7 and R8) are used for color vision by comparing ultraviolet light (UV), detected by R7, with green or blue light detected by two types of R8. The NYU and University of Würzburg biologists investigated how photoreceptor types contribute to phototaxis by blocking the function of either R7 or R8, or a combination of a range of photoreceptors (R1-R6, R7 and/or R8).

In the study, they constructed two sets of "Y-shaped mazes" with two different types of light at the ends of each: UV and blue in one and blue and green in the other. Under this arrangement, the fly would show a preference for certain type of light (UV vs. blue in one maze; blue vs. green in the other) by moving toward it. The researchers could then link specific preferences to the make-up of each fly's visual system.

In a "UV vs. blue" choice, flies with only R1-R6 and flies with only R7/R8 photoreceptors preferred the blue to the UV light. This finding suggested that these two sets of photoreceptors (R1-R6 and R7/R8) function separately in phototaxis as flies with only one of these sets showed similar preferences. In addition, flies without a functioning R7 photoreceptor preferred the blue to the UV light, whereas flies without R8 preferred UV. In the "blue vs. green" maze, flies without a functioning blue R8 photoreceptor preferred green, whereas those with a defective for green R8 photoreceptor preferred blue. This shows that each subclass of photoreceptors [R1-R6, R7, R8 (blue), R8 (green)] is used by the fly to distinguish colors and setup its innate color preference. In a previous work, the same authors had shown that motion detection only involves R1-R6 and not R7 and R8, suggesting that there are two independent channels in the fly visual system -- one for motion and one for color.

"This simple insect can achieve sophisticated color discrimination and detect a broader spectrum of colors than we can, especially in the UV," said NYU biologist Claude Desplan, one of the study's authors. "It is a great model system to understand how the Retina and the brain process visual information.

The research was supported by a grant from the National Institutes of Health.

http://www.sciencedaily.com/releases/2010/03/100308151051.htm

The above story is reprinted from materials provided by New York University, via EurekAlert!, a service of AAAS.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

New Glaucoma Test Allows Earlier, More Accurate Detection

noreply@blogger.com (drwrigley) — Mon, 13 Feb 2012 18:39:00 +0000

New Glaucoma Test Allows Earlier, More Accurate Detection

Cumbersome Glaucoma tests that require a visit to the ophthalmologist could soon be history thanks to a home test developed by a UA engineer.

While the probe is simple to use, the technology behind it is complex, involving a system of micro-force sensors, specially designed microchips, and math-based procedures programmed into its memory.

The National Science Foundation has funded the work, and Enikov and Peyman now are seeking investors to help fund final development and commercialization of the product.

"One of the reasons pressure builds up in the eye is because fluid doesn't drain properly," Enikov noted. "Currently, there are no methods available to test drainage."

Current tests require applying pressure directly to the cornea, but only very light pressure is safe to use, and it doesn't cause the fluid to drain.

Instead, it presses the entire eyeball, much as you might press a balloon to determine its stiffness.

http://www.sciencedaily.com/releases/2011/01/110104101331.htm

The above story is reprinted from materials provided by University of Arizona College of Engineering. The original article was written by Ed Stiles.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

The Pupils Are the Windows to the Mind

noreply@blogger.com (drwrigley) — Wed, 01 Feb 2012 15:58:00 +0000

Untitled Document

The Pupils Are the Windows to the Mind

The eyes are the window into the soul -- or at least the mind, according to a new paper published in Perspectives on Psychological Science, a journal of the Association for Psychological Science. Measuring the diameter of the Pupil, the part of the eye that changes size to let in more light, can show what a person is paying attention to. Pupillometry, as it's called, has been used in social psychology, clinical psychology, humans, animals, children, infants -- and it should be used even more, the authors say.

The Pupil is best known for changing size in reaction to light. In a dark room, your Pupils open wide to let in more light; as soon as you step outside into the sunlight, the Pupils shrink to pinpricks. This keeps the retina at the back of the eye from being overwhelmed by bright light. Something similar happens in response to psychological stimuli, says Bruno Laeng of the University of Oslo, who cowrote the paper with Sylvain Sirois of Université du Québec à Trois-Rivières and Gustaf Gredebäck of Uppsala University in Sweden. When someone sees something they want to pay closer attention to, the Pupil enlarges. It's not clear why this happens, Laeng says. "One idea is that, by essentially enlarging the field of the visual input, it's beneficial to visual exploration," he says.

However it works, psychological scientists can use the fact that people's Pupils widen when they see something they're interested in.

Laeng has used Pupil size to study people who had damage to the hippocampus, which usually causes very severe amnesia. Normally, if you show one of these patients a series of pictures, then take a short break, then show them another series of pictures, they don't know which ones they've seen before and which ones are new. But Laeng measured patients' Pupils while they did this test and found that the patients did actually respond differently to the pictures they had seen before. "In a way, this is good news, because it shows that some of the brains of these patients, unknown to themselves, is actually capable of making the distinction," he says.

Pupil measurement might also be useful for studying babies. Tiny infants can't tell you what they're paying attention to. "Developmental psychologists have used all kinds of methods to get this information without using language," Laeng says. Seeing what babies are interested in can give clues to what they're able to recognize -- different shapes or sounds, for example. A researcher might show a child two images side by side and see which one they look at for longer. Measuring the size of a baby's pupils could do the same without needing a comparison.

The technology already exists for measuring pupils -- many modern psychology studies use eye-tracking technology, for example, to see what a subject is looking at, and Laeng and his coauthors hope to convince other psychological scientists to use this method.

http://www.sciencedaily.com/releases/2012/01/120127162800.htm

The above story is reprinted from materials provided by Association for Psychological Science.