Diabetes has assumed epidemic proportions in India in general and Kerala in particular. From a reported 19 million cases in 1995, it is estimated that the diabetic population in India would go up to 57 million in 2025.
High blood sugar levels, seen in diabetes, can damage blood vessels in the retina (the nervous layer that senses light and helps to send images to the brain). This damage to retinal vesels results.
There are two stages of diabetic retinopathy: Non Proliferative (NPDR) and Proliferative (PDR). NPDR (background diabtic retinopathy), is an early state of the disease where tiny blood vessels within the retina leak blood or fluid causing the retina to swell or to form cholesterol deposits (hard exudates) in the central area of retina (macula).
If untreated, retinopathy may progress to PDQR where abnormal new vessels grow from the surface of the retina and optic nerve accompanied by proliferation of fibrous tissue, which shrinks and causes recurrent bleeding or detaches the retina from its normal position. There may be proliferation of new vessels in the front portion of the eye leading to a very painful blind eye due to neovascular glaucoma.
Thus, the causes for visual loss (sometimes profound) in diabetic retinopathy are mainly macular oedema, recurrent vitreous haemorrhage into clear gel (vitreous) that fills the cavity of the eye and traction retinal detachment. The retinal changes are permanent and progressive and hence the best form of treatment is to prevent development of retinopathy. Strict diabetic control will significantly lower this risk. If high blood pressure, raised choloesterol levels and kidney problems are present they need to be evaluated and treated.
A regular and frequent examination of the eye is the only way to detect diabetic retinopathy. Your pupils must be dilated to permit a thorough examination of the retina with an opthalmoscope. A special test called fluorescein fundus angigram may have to be performed to stage the disease and find out if treatment is required. In this test a dye called fluorescein is injected into the arm vein and photos of the eye are taken to detect where fluid is leaking. OCT (Ocular Coherence Tomography) is an useful too in evaluating patients with diabetic macular acdema as it will help screen cases that will benefit from vitrecus surgery. Laser treatment is recommended for patients with macular oedema and proliferative retinopathy. The main goal of laser therapy is to prevent further loss of vision by decreasing the fluid leakage at the macula and by shrinking the abnormal new vessels thereby preventing recurrent bleeding. Multiple laser treatments over time are sometimes required. Cataract frequently co-exists with the complications of diabetic retinopathy making visualization for laser treatment and surgery difficult. This can be safely managed by phacoemulsification (keyhole surgey) which is ideal for diabetic patients.
Vitrectomy is a microsurgical procedure in which the blood filling the vitreous cavity is removed replacing it with a clear fluid. During this procedure, additional steps are performed to remove bleeding vascular membranes, repairing a detached retina and completing laser photocogulation.
If you are a diabetic, it is important to know that with the available methods it is possible to diagnose, stabilize your retionopathy and prevent severe visual loss.
Chakrabarti Eye Care Centre