The center of the retina (Macula), which is responsible for fine visual function, may develop swelling from retinal vessel leakage. This macular swelling (Maculopathy) can cause visual loss. The patient may not notice early macular swelling causing subtle visual defects such as distorted vision or mild blurring, and hence the importance of routine eye examinations in diabetics is critical.
This can progress to the next stage called Proliferative Retinopathy, i.e., the formation of abnormal blood vessels (neovascularization) that grow out of the retina. These vessels will usually bleed into the vitreous, causing severe and sudden visual loss, or they pull on the retina resulting in a retinal tear. In many patients, bleeding and retinal detachment occur.
The most recent and useful test available for this is called OCT (Optical Coherence Tomography). This is a painless and quick scan of the macula, which gives us information about the thickness of the retina and any other abnormalities like swelling, membrane formation etc. The other important test is Retinal Angiography.
It is also known as Fluorescein Angiography. It is done in the OPD. A colored dye (fluorescein sodium) is injected in the vein and the patient sits in front of a retinal camera, which takes serial photos of the dye flowing through the retinal blood vessels. It can pick up early diabetic retinal damage, swelling and leakage from the retina at all stages of the disease, as well as help us predict the visual improvement that the patient can achieve after successful treatment.
The treatment depends on the type and stage of the retinopathy. Maculopathy can be treated with Intravitreal Injections of Anti VEGF drugs like Avastin, Lucentis and Macugen, or Steroids like Ozurdex or Triamcinolone, depending on the severity and risk factors. Multiple injections may be required to keep this condition under control. These injections will have to be supplemented with Laser treatment in most cases.
The treatment is usually by laser to the leaking blood vessels. However, patients with severe bleeding or retinal detachment involving the central vision usually require surgery. Laser treatments for either retinal swelling or leaky blood vessels are performed as an outpatient procedure. Treatments may be divided into several sittings over a few weeks, depending on the severity. The treatment is painless.
Vitreous surgery for Diabetic Retinopathy is done to remove blood, reattach the retina, or both. This procedure is called Vitrectomy. Fine microsurgical instruments such as scissors, picks, forceps, laser probe etc. are introduced into tiny openings in the side of the eye, and the procedure is usually done under local anesthesia as a day care procedure. In some cases, an expansible gas or silicon oil is injected in the eye to stabilize the retina after the surgery.
Good diabetic control along with good control of other medical problems like hypertension, kidney disease, cholesterol (lipids) produces many benefits, including slowing down the development of retinal complications. Even with excellent control, many patients may still develop retinopathy. Therefore, regular eye examinations are very important.
A patient with diabetes should have a dilated pupil examination of the retina at the time of diagnosis and a minimum of once a year for life. Some patients with early diabetic retinal disease may require more frequent examination.
Successful treatment of Diabetic Retinopathy depends on early detection and regular follow up. This is the best protection against severe loss of sight.