Putting lazy eyes into the dark?

An eye is considered lazy when vision is mildly to severely reduced. This can be due to a variety of reasons but the most common causes are high prescriptions and crossed eyes. Interestingly it is not the eye that is “lazy”, rather the brain’s vision center. In my practice I do not use the term lazy eye. Instead I use the more appropriate medical term “amblyopia” to describe the eye condition that is prevalent in 2% of the population.

Amblyopia begins early in childhood during critical developmental years. Neuron pathways are forming during this time and what our eyes see (or do not see) affects how good our vision develops. In fact the amazing thing about human neurological development is the ability of our brain to adapt and change according to environmental stimuli. Early in our lives our brain uses input from the environment to form patterns that allow it to be more efficient. Eventually, it loses plasticity and the ability to adjust to new patterns decreases significantly.  In the case of amblyopia, the brain learns to shut out input from an eye with an uncorrected prescription or crossed eye. Traditionally doctors have considered this to be a permanent reduction in vision when not corrected by age 8.

A new solution?

Researchers Kevin Duffy and Donald Mitchell of Dalhousie University recently conducted a study to return the brain back to its early development stages in an attempt to increase its flexibility. They believe this can serve to reset the brain. The study was conducted on kittens with induced amblyopia who were immersed in a pitch black room for ten days. After the ten days vision significantly improved in all subjects! The positive results of the experiments led researchers to believe the treatment may work on children and young adults with amblyopia. However, in order for this treatment to be effective subjects must be completely isolated from light for long periods of time.

The practicality of this treatment is questionable and I am not yet recommending patients to stay in a pitch dark room for an extended period of time.  I am optimistic about the possibility of a brain “reset” and look forward to further developments. I will still maintain that the key to an amblyopia treatment program is to start at an early age while the brain has great plasticity.

Written with Ian Gao, Optometry Intern, College of Optometry ,Western University of Health Sciences

Birth Control Linked to Glaucoma?

Annual eye examinations are recommended for a variety of reasons including maintaining optimum vision, examining for signs of systemic disease and evaluating the effects of prescription medications on the eyes. The latter of these was emphasized recently with a recent study involving women and birth control. In fact, 10.7 million women used oral contraception in the United States between 2006-2008 according to the Centers for Disease Control.

The study, presented at the American Academy of Ophthalmology Annual Meeting, suggests that there is an increased risk of developing glaucoma in women who have been taking oral contraceptives for three or more years. Researchers from several universities, the closest locally being The University of California, San Francisco used data from a 2005-2008 National Health and Nutrition Examination Survey.

3,406 participants over 40 years old were surveyed on their visual and reproductive health followed by an eye examination. The results showed that women who have been on oral contraceptives for 3 or more years were 2 times more likely to be at risk for being diagnosed with glaucoma compared to women not taking it or for fewer years.

While the study does not show a direct link that long term contraceptive use can cause glaucoma, contraceptive use can be a risk factor that patients and doctors need to monitor. This is especially important if other risk factors for glaucoma such as ethnicity, family history, eye anatomy, or medication are present.  Interestingly, other studies have shown that estrogen is linked to the development of glaucoma, which could be why oral contraceptives, which work by altering estrogen levels, is a risk factor for glaucoma.

Contributed by Peggy Zhu, Optometry Intern, College of Optometry ,Western University of Health Sciences