Posts Tagged ‘vision’

Schizophrenia is associated with structural and functional alterations of the visual system, including specific structural changes in the eye. Tracking such changes may provide new measures of risk for, and progression of the disease, according to a literature review published online in the journal Schizophrenia Research: Cognition, authored by researchers at New York Eye and Ear Infirmary of Mount Sinai and Rutgers University.

Individuals with schizophrenia have trouble with social interactions and in recognizing what is real. Past research has suggested that, in schizophrenia, abnormalities in the way the brain processes visual information contribute to these problems by making it harder to track moving objects, perceive depth, draw contrast between light and dark or different colors, organize visual elements into shapes, and recognize facial expressions. Surprisingly though, there has been very little prior work investigating whether differences in the retina or other eye structures contribute to these disturbances.

“Our analysis of many studies suggests that measuring retinal changes may help doctors in the future to adjust schizophrenia treatment for each patient,” said study co-author Richard B. Rosen, MD, Director of Ophthalmology Research, New York Eye and Ear Infirmary of Mount Sinai, and Professor of Ophthalmology, Icahn School of Medicine at Mount Sinai. “More studies are needed to drive the understanding of the contribution of retinal and other ocular pathology to disturbances seen in these patients, and our results will help guide future research.”

The link between vision problems and schizophrenia is well established, with as many as 62 percent of adult patients with schizophrenia experience visual distortions involving form, motion, or color. One past study found that poorer visual acuity at four years of age predicted a diagnosis of schizophrenia in adulthood, and another that children who later develop schizophrenia have elevated rates of strabismus, or misalignment of the eyes, compared to the general population.

Dr. Rosen and Steven M. Silverstein, PhD, Director of the Division of Schizophrenia Research at Rutgers University Behavioral Health Care, were the lead authors of the analysis, which examined the results of approximately 170 existing studies and grouped the findings into multiple categories, including changes in the retina vs. other parts of the eye, and changes related to dopamine vs. other neurotransmitters, key brain chemicals associated with the disease.

The newly published review found multiple, replicated, indicators of eye abnormalities in schizophrenia. One of these involves widening of small blood vessels in the eyes of schizophrenia patients, and in young people at high risk for the disorder, perhaps caused by chronic low oxygen supply to the brain. This could explain several key vision changes and serve as a marker of disease risk and worsening. Also important in this regard was thinning of the retinal nerve fiber layer in schizophrenia, which is known to be related to the onset of hallucinations and visual acuity problems in patients with Parkinson’s disease. In addition, abnormal electrical responses by retinal cells exposed to light (as measured by electroretinography) suggest cellular-level differences in the eyes of schizophrenia patients, and may represents a third useful measure of disease progression, according to the authors.

In addition, the review highlighted the potentially detrimental effects of dopamine receptor-blocking medications on visual function in schizophrenia (secondary to their retinal effects), and the need for further research on effects of excessive retinal glutamate on visual disturbances in the disorder.

Interestingly, the analysis found that there are no reports of people with schizophrenia who were born blind, suggesting that congenital blindness may completely or partially protect against the development of schizophrenia. Because congenitally blind people tend to have cognitive abilities in certain domains (e.g., attention) that are superior to those of healthy individuals, understanding brain re-organization after blindness may have implications for designing cognitive remediation interventions for people with schizophrenia.

“The retina develops from the same tissue as the brain,” said Dr. Rosen. “Thus retinal changes may parallel or mirror the integrity of brain structure and function. When present in children, these changes may suggest an increased risk for schizophrenia in later life. Additional research is needed to clarify these relationships, with the goals of better predicting emergence of schizophrenia, and of predicting relapse and treatment response and people diagnosed with the condition.”

Dr. Silverstein points out that, to date, vision has been understudied in schizophrenia, and studies of the retina and other ocular structures in the disorder are in their infancy. However, he added, “because it is much faster and less expensive to obtain data on retinal structure and function, compared to brain structure and function, measures of retinal and ocular structure and function may have an important role in both future research studies and the routine clinical care of people with schizophrenia.”

http://www.eurekalert.org/pub_releases/2015-08/tmsh-rcm081715.php

A student in Taiwan who kept a pair of disposable contact lenses in her eyes for six months has been left blinded after a microscopic bug devoured her eyeballs.

The tiny single-cell amoeba ate away at undergraduate Lian Kao’s sight because she didn’t take out and clean the contacts once during that time.

According to a warning issued by doctors the case was a particularly severe example of a young person under pressure who did not take the time to carry out basic hygiene on their contact lenses

As well as being regularly cleaned, contact lenses should also be removed when swimming and washing.

The general advice is to avoid wearing contacts for more than eight hours a day.

Yet apparently 23-year-old Kao had even kept her contact lenses in at all times, even at the swimming pool.

Medics were horrified when they removed the contact lenses to find that the surface of the girl’s eyes had literally been eaten by the amoeba that had been able to breed in the perfect conditions that existed between the contact lens and the eye.

The director of ophthalmology at Taipei’s Wan Fang Hospital, Wu Jian-liang, said: ‘Contact lens wearers are a high-risk group that can easily be exposed to eye diseases.

‘A shortage of oxygen can destroy the surface of the epithelial tissue, creating tiny wounds into which the bacteria can easily infect, spreading to the rest of the eye and providing a perfect breeding ground.

‘The girl should have thrown the contact lenses away after a month but instead she overused them and has now permanently damaged her corneas.’

He said that she had been diagnosed with acanthamoeba keratitis, which although rare was always more common in the summer.

He confirmed and spoke about the girl’s case as a way of urging others to be more careful if they had to use contact lenses.

The problem is the condition can build up over several years – it’s only when it gets to an advanced stage that contacts wearers become aware of a problem, as that’s when it will cause red, irritated eyes, by which time it may be too late.

Acanthamoeba bugs stick to contact lenses and can then burrow their way through the cornea, causing acute pain.

It’s only at this stage that a sufferer would be aware they had a problem.

Prescription drugs may be able to treat the bug in the early stages, but specialists say it is very difficult to get rid of. In serious cases, the patient needs a corneal transplant but these have a high failure rate, resulting in sight loss.

Other steps to prevent the infection include never swimming or using a hot tub or shower when wearing contacts.

Each year, infections cause around 6,000 cases of a severe eye condition known as microbial keratitis – inflammation and ulceration of the cornea that can lead to vision loss.

Contact lens wearers are at a higher risk, since bacteria can get trapped in the lenses.

Read more: http://www.dailymail.co.uk/news/article-2687477/Student-goes-blind-keeping-contact-lenses-six-months-microscopic-bug-EATS-eyeballs.html#ixzz37dnGxTKv

Thanks to Pete Cuomo for bringing this to the attention of the It’s Interesting community.