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How can diabetes affect your eyes?

By Dr Rusina Karia

Diabetes is an emerging epidemic all over the world. There are almost 79 million people with diabetes in India, one of the highest in the world. While the disease itself is a source of concern, complications arising from diabetes can be dangerous if ignored. Diabetic ocular complications fall in this category. Recent research shows almost every patient of type I diabetes and more than half the patients of type II diabetes, will suffer from diabetic retinopathy during the course of the disease, which can lead to blindness if left untreated.

There are five ocular complications to be aware of: Diabetic Retinopthy (DR), Glaucoma, Diabetic papillopathy (DP), Cataract and Dry Eye Syndrome.

Diabetic Retinopathy:

The underlying pathogenesis of DR are the microvascular changes in the ocular arterioles due to hyperglycemia. This leads to decreased blood supply of the retinal cells, inflammation and ultimately their death. As a consequence, the disease can progress to blindness.     

DR can occur within 5 years of diabetes. Hence a fundus examination should be done at the time of diagnosis of diabetes and then annually. The treatment of DR is complete metabolic control and intravitreal injections of steroids and anti- VEGF agents. If DR continues to progress, then laser photocoagulation treatment can be considered. Pars plana vitrectomy (PPV), a surgical procedure is performed when all the above treatment methods fail.

Glaucoma:

There is a fluid called the aqueous humor inside the eyes and a network is present within the eyes for its drainage and circulation. Glaucoma is a disease in which this drainage is blocked and the fluid accumulates within the eyes creating pressure. In diabetes, there is formation of unwanted extra blood vessels within the iris which blocks the pathway of drainage for the aqueous humor. This is called the neovascular type of glaucoma.                                                                                                                Measurement of the intraocular pressure (IOP) by tonometers is a quick way to diagnose glaucoma. An IOP between 10 – 20 mmHg is considered normal. In glaucoma, a raised IOP will be noted. Panretinal photocoagulation is a laser treatment performed to prevent and treat neovascular diabetic glaucoma.

Cataract:

The pathogenesis of this ocular complication is that excess glucose in diabetes undergoes a reaction with the proteins in the lens and leads to its opacification. Although cataract is a common disease in older patients, in a diabetic patient it occurs at a younger age and is also more prone to progress rapidly.            

A full ophthalmologic examination including slit lamp microscopy, gonioscopy, fundus examination post dilation and visual acuity should be performed to diagnose and establish the progress of the cataract. Prevention of diabetic cataract can be achieved by tight glucose control. But once cataract sets in, surgical lens removal by the method of phacoemulsification is the mainstay of diabetic cataract treatment.

Dry Eye Syndrome:

Diabetes impairs the production of tears and mucin, responsible for reduction of tear evaporation. This leads to a dry eye symptomatically manifesting as a burning and/or foreign body sensation in the eye. The tests to diagnose dry eye are the TBUT test to determine tear film quality and Schirmer test which detects tear formation deficiency. Since a patient suffering from dry eye has a deficiency of tears, artificial tears are supplemented everyday in the form of eye drops. Anti-inflammatory agents like NSAIDS and topical steroids are also used.

Diabetic Papillopathy (DP):

This is an uncommon ocular complication of diabetes. Pathogenesis of DP is unclear but thought to be optic disc swelling due to damage of the peripapillary blood vessels by the excess glucose.                    Symptomatic features like painless vision loss and fluorescein angiography test are used to diagnose DP. Ocular Steroids and anti-VEGF intravitreal injections are the current treatment methods for DP.

Diabetes is a chronic disease with serious consequences. It affects most major organs of the body and needs regular visits to the physician. The best way to prevent ocular complications is a constant vigilance of the blood glucose levels. A personal awareness of the diabetic complications and its symptoms is required so you can take the right decisions on the best way to tackle your condition.

 

(Dr Rusina Karia is a doctor by profession. She did her MBBS from Maharasthra, India and went on to do her research fellowship  from Midwest Cardiovascular Research Foundation, Iowa. She  is the author of various research publications published in different renowned journals.)

Tags: ocular, diabetes retinopathy

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