Scientists have discovered that the brain, not the eye, controls the cellular process that leads to glaucoma.
The study has found that in humans the brain plays a part in pruning optic nerve axon cells that can lead to vision loss. To reach this conclusion, ophthalmologists performed a data and symmetry analysis of 47 patients with moderate to severe glaucoma in both eyes.
In glaucoma, the loss of vision in each eye appears to be haphazard. They discovered that as previously disabled optic nerve axons recover, the remaining areas of permanent visual loss in one eye coincide with the areas that can still see in the other eye.
The team found that the visual field of the two eyes fit together like a jigsaw puzzle, resulting in much better vision with both eyes open than could possibly arise by chance.
"As age and other insults to ocular health take their toll on each eye, discrete bundles of the small axons within the larger optic nerve are sacrificed so the rest of the axons can continue to carry sight information to the brain," explained William Eric Sponsel from the University of Texas at San Antonio, department of biomedical engineering.
"The entire phenomenon appears to be under the meticulous control of the brain," Sponsel added.
According to researchers, the cellular process used for pruning small optic nerve axons in glaucoma is remarkably similar to the apoptotic mechanism that operates in the brains of people afflicted with ‘Alzheimer's disease’.
The results may help develop new treatments as well as contribute to the development of future therapies for preserving brain function in other age-related disorders like Alzheimer's.
The research appeared in the journal Translational Vision Science Technology (TVST).