The retina is the most important part of the eye. It is the continuation for the central nervous system (CNS) and the only part of the eye that is visible from the outside. It has about 125 million photosensitive cells called cones and rods non-uniformly distributed over the entire retina. Retina occupies 65% of the inside of the eyeball.The central portion has the most acute, well defined, color discerned vision.The light falling on the retina is converted to electrical signals through a complex chemical-electrical reactions and the optic nerve carries these signals to the brain for interpretation and image formation.
Retina suffers a set of disorders. The most important and significant ones are retinal tear and detachment. Another is diabetic retinopathy and age-related macular degeneration. Retinal tear is caused by the contraction of the gel-like vitreous pulling the retina down. Retina is a delicate membranous structure and when pulled, it easily tears. The fluids seep through the tear and collect behind the retina and separates it from the underlying tissue This is retinal detachment. The symptoms are more or less the same and includes seeing an increased number of bright, rather biggish sparks, and other floaters. The treatment is to seal the tear using an appropriate method, like cryopexy photocoagulation, pneumatic retinopexy or vitrectomy.
Diabetic retinopathy is caused by diabetes when abnormal capillaries form and bleed into the retina or the capillaries behind retina deteriorate and ooze out fluids and blood. The best bet is to prevent diabetes from progressing to this stage. Regular eye check help detect the development of retinopathy at a very early stage even before the symptoms set in. Injections of medicine like anti VEGF which stops formation of abnormal capillaries can help. In advanced cases, scatter laser treatment is used. In this, 1000 to 2000 spot coagulations are done. This shrinks these capillaries and discourages the formation of newer ones. If situation demands, vitrectomy is also resorted to.
Macular hole is caused by an injury or as one ages the vitreous shrinks and pulls the retina. Sometimes a portion or the macula can tear. The treatment is vitrectomy, where the vitreous is replaced with gas. The gas presses the macula back to the eye wall. In a week or so it heals. Macular tissue degenerates as one ages. Anti-vascular endothelial growth factor (VEGF) is injected into the eye.