Diabetic Retinopathy:The retina is a thin, clear tissue that lines the back of the eye. It is
made up of sensitive nerve cells that capture light like the film in a camera. The picture
is sent from the retina through the optic nerve to the brain where it is interpreted. The macula is the small center area of retina that is
responsible for fine detail, color and straight ahead vision. The peripheral retina
provides vision in dim light and side vision. Blood vessels in the retina circulate oxygen
and nutrients to the tissue to keep it healthy.
Diabetes can cause damage to the blood vessels in the retina.
Damaged blood vessels allow blood and fluid to leak, leaving tiny hemorrhages and exudates
in the retinal tissue. This condition is called nonproliferative diabetic retinopathy.
Vision may not be affected at this point if the leakage is not near the macula. Leakage of
fluid into the macula that causes swelling is called macular edema. Center vision may be
blurred especially for reading and fine work.
Diabetes can also cause the small blood vessels
in the retina to close, preventing the delivery of oxygen and nutrition to the retinal
tissue. The retina becomes unhealthy and responds by growing abnormal new blood vessels
and scar tissue. The new blood vessels, called neovascularization, are very fragile and
can hemorrhage causing severe vision loss. At this stage the disease is called proliferative diabetic retinopathy.
Vision may be normal at the time of diagnosis if the new blood vessels are not bleeding.
Black or red spots in the vision can indicate bleeding into the vitreous, the clear jelly that fills the eye. A large
hemorrhage into the vitreous will cause a sudden decrease in vision. A reduction in side
vision or ability to see well in dim light may be a sign that the peripheral retina is
unhealthy.
