Binocular vision is a good thing. It allows humans to judge distance and depth, which gives us the ability to distinguish the relationship between objects. When the eyes aren’t in their correct position or can’t focus on the same object, then there are vision problems. It can lead to conditions such as strabismus, also known as cross-eye or amblyopia, also known as lazy eye.
These conditions can be corrected provided that they are diagnosed in children age 8 and younger. The reason for that has to do with the fact the that brain has more plasticity in childhood. Researchers at University of Utah Health have found a gene, known as Arc, that regulates the development of neurons in the brain that lead to binocular vision. Discovery of this gene strengthens previous research that show that Arc plays an important role in brain plasticity.
Since Arc plays a role in brain plasticity, the hope is to tweak the gene so as to improve brain plasticity and make the brain work better. Jason D. Shepherd, Ph.D., the study’s senior author and an associate professor in the University of Utah Health Department of Neurology and Anatomy focused on Arc’s part in the development of binocular vision neurons in the visual cortex. They studied the neurons of mice that were placed in a darkened room for long periods of time. These mice didn’t produce the binocular neurons, which shows that daily life experiences are needed to start the development of the cells.
Researchers used a powerful microscope to see the real-time development of the binocular neurons in young mice that were exposed to vertical and horizontal bars and other shapes. Next, they disabled the Arc gene in the mice. The expectation was that the mice wouldn’t develop the binocular neurons. Instead, they developed more binocular neurons. This was also done to adult mice with the similar results. These results show that brain plasticity lasts longer than was once thought.
As great as it was that these neurons developed in the Arc-deficient mice, they weren’t fully functional. Based on the study’s finding, researchers think that Arc acts like a brake to keep the neurons under control, so that they don’t produce too little or too much.
Still, there are treatments in the here and now that help with binocular vision. In particular, studies on adults with convergence insufficiency have shown that 62 percent of patients who received in-office plus home therapy saw an improvement in vision. Treatment for convergence insufficiency include brock string for convergence work, monocular accommodative facility or near far Hart Chart for accommodation. After a while, therapy can advance to vectograms, aperture rule and lifesaver cards.
Other therapies for pediatric patients with amblyopia include red/green targets, as well as playing cards and commercially available matching games. Many optometrists utilize monocular fixation in a binocular field (MFBF). This is where the patient wears a red filter over the good eye and completes activities using a red pencil or pen that can be seen by the amblyopic eye. Another binocular therapy option involves virtual reality. There is a program that utilizes virtual reality goggles to treat amblyopia, strabismus and vergence disorders. The patient plays a game with these goggles where they either stop targets or pop targets with their hands.
While therapies now exist for strabismus and amblyopia, thanks to ongoing research on the genetic building blocks of vision, there will be treatments for these condition that can work on patients who are older than 8 years of age.