Effects of diabetes on eyes

Diabetes is a chronic disease and not a single organ is spared from its effects. The incidence of diabetes is rising exponentially. As far as effect of diabetes on eyes are concerned, it should be remeberred that in India, diabetes ranks the second most common cause of blindness, just after cataract, while in many Western Countries, it is so far the most common cause of blindness.

It is a well known fact that retinopathy can occur in many Type 2 diabetes mellitus patients, thus a it is essential to have a basic baseline evaluation of vision in all patients with type 2 diabetes.

Visual evaluation in diabetes

A visual evaluation in a patient of diabetes should include a complete nd detailed history of visual symptoms. There may not be complete loss of vision initially, but blurring of vision, double images and difficulty in reading may be seen and should be assessed.

Measurement of visual acuity and intraocular pressure is mandatory. Refractory errors should always be corrected after a period of stable control. Cataract and glaucoma, specially open angle glaucoma are more common in diabetics and should be actively assessed with special focus and attention.

Ophthalmic examination through dilated pupil should be done and retina should be examined by fundoscopy and retinoscopy to see and neovascularization or any small microaneurysm which are the earliest changes in eyes of a diabetic.

Patients of diabetes at special risk for eye problems

It is necessary to give a special attention to patients who are at special risk. The patients at special risk include

* Diabetic women who are planning a pregnancy. In these women a detailed eye examination should be done. A person must know that mere checking of refractory error at Snellens chart is not enough for a detailed eye examination. Retina, choroid and fundus should be examined in detail by an ophthalmoscope.

* All pregnant should undergo a detailed eye examination for the presence of retinopathy at the time of diagnosis and then as frequently as required depending on the findings and conditions.

* Those patients who are hypertensive and are smokers are at special risk. If the urine shows the presence of microalbuminuria, then also that patient is at special risk and should be dealt accordingly.

* A patient having detoriation in visual acuity or having an unexplained visual symptoms, retinal abnormalities or increase in intraocular pressure with or without frank glaucoma are at special risk.

* Any patient having retinopathy which may be either preproliferative which constitutes findings like cotton wool spots on retina, multiple intraretinal hemorrhage, venous beading or intraretinal microvascular changes or abnormalities, or with proliferative retinopathy including features like preretinal or vitreous hemorrage, formation of new blood vessels in retina called neovascularization, traction retinal detachment or fibrosis of the vessels or with macular edema haqving features or hard exudates constituting lipids.

The examination of the eye in these patients at high risk should always be done at regular interval as once a frank diabetic retinopathy occurs, it is tough to treat.
One should follow the schedule of eye examination as mentioned below as prevention is always a better step than cure.

Schedule of examination of eye in diabetes

The schedule of examination of eye depends on the type of diabetes and condition of the patient if there is an special case like pregnancy. The schedule recommended is as follows-

Examination schedule of eye in Type 1 diabetes

Type 1 diabetes is not age related and can be present even in young ones and is insulin dependent. As diabetic retinapathy depends on the duration and not the extent of blood glucose, the first examination of the eye is recommended within 3 to 5 years after the diagnosis of the diabetes once the patient is above 10 years of age. The follow up examination should be done annually even if there is no signs and symptoms.

Examination schedule of eye in Type 2 diabetes

Type 2 diabetes is often seen in obese and is mostly affected by environmental factors. There is a possibility of presence of diabetes much earlier than it has been diagnosed, thus the examination of eye should be done as soon the diabetes is diagnosed and then an annual follow up should be maintained even if there is no features of eye involvement.

Examination schedule of eye in Pregnancy with preexisting diabetes

Pregnancy with preexisting diabetes is always at higher risk, during pregnancy the glucose level may further rise. The examination schedule of eyes should be followed prior to conception if there is preexisting diabetes and then during first trimester to assess the effect of pregnancy in diabetes and ultimately to eyes. The follow up depends on the result of examination of first trimester.

Thus a diabetic patient should have a special precaution for their eyes and an alert approach and regular check up can lead to decreased incidence of blindness and even other eye problems.