Expert-reviewed by Ashwini S.Kanade, Registered Dietician and Certified Diabetes Educator with 17 years of experience
The eye is a small but complex organ composed of various parts, many of which are sensitive to metabolic changes in the blood.
Diabetes makes the eye more prone to complications, such as dry eye, blurry vision, cataract, and diabetic retinopathy—a serious condition affecting the retina. (1) Anywhere between 20% and 40% of individuals with type 2 diabetes develop diabetic retinopathy, although the frequency is generally somewhat lower in Asian countries (23% in India) than Western countries. (2) Diabetes is a common cause of visual impairment, and can even lead to blindness.
How does diabetes cause eye disease?
Hyperglycemia (high blood sugar) disrupts the normal balance of forces that keep the blood inside the capillaries (small connector blood vessels). As a result, fluid leaks out or capillaries become blocked. Other mechanisms come into play, producing substances (such as advanced glycation end products) that harm the retina.
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What types of eye diseases can occur?
Minor issues such as dry eye to serious consequences such as blindness can occur due to severe diabetic retinopathy. Often, an individual with diabetes may not be aware of this until the disease reaches a more advanced age.
1. Dry eye:
Most individuals with diabetes have at least mild dry eye. However, in many people, the sensitivity of the cornea decreases, which prevents them from noticing dry eye and seeking treatment (which is artificial tears). (2) Dry eye should be paid attention to as apart from being bothersome, it can damage the surface of your eye if left untreated for long.
Individuals with diabetes are more prone to developing eye infections, such as that of the eyelids, cornea, and conjunctivitis (pink eye). Strict management of blood sugar is essential, and in case an infection is noticed, it should be treated at the earliest.
This is one of the well-known eye complications of diabetes. Cataract is the clouding over of the lens inside the eye, which impairs one’s vision. The risk of cataract increases as much as four times in adults (younger than 65 years) with diabetes. Hyperglycemia is strongly linked to cataract formation, including even the state of prediabetes (with fasting blood glucose 110 to 125 mg/dL). The good news is that with rigorous sugar management, some milder forms of diabetes-induced cataract may actually clear up. Treatment of cataract is the removal of the affected lens by surgery and implantation of an artificial lens in its place. (3)
It is an increase in fluid pressure inside the eye. In early stages, there may be no symptoms, but over the long term, vision problems may be caused by compression of the optic nerve. About 10% of people with glaucoma can have total vision loss if left untreated. (3) Glaucoma is easily detected in the eye clinic.
5. Diabetic retinopathy:
This is perhaps the most severe eye complication of diabetes and is one of the most common causes of vision loss in adults. (2) Diabetic retinopathy affects the retina, and while in the beginning there may not be any symptoms, there is a gradual reduction in vision and sometimes blindness. Three factors are perhaps the most important in the progression of diabetic retinopathy: duration of diabetes, hyperglycemia, and high blood pressure. Moreover, diabetic retinopathy and lifestyle (including other lifestyle diseases) are linked to each other. It is usually treated by laser or surgery depending on the severity (panretinal laser photocoagulation or pars-plana vitrectomy), although medications may be effective to an extent. (3) Mild diabetic retinopathy may reduce by 1 or 2 stages in some patients, thereby making a strong case for having strict blood sugar management. (2)
Here’s everything you need to know about diabetes-related complications.
If you have recently been diagnosed with diabetes or even prediabetes, it is recommended that you schedule a checkup with an ophthalmologist. (1) This should be followed by annual eye check-ups because, as mentioned earlier, symptoms of many of the eye-related complications do not appear until an advanced stage. If you have any eye problems—particularly, vision problems, new or sudden difficulty in reading, changes in colour perception, or seeing spots—you should schedule an appointment as soon as possible. And if you already have diabetic retinopathy, depending on the severity, your doctor will ask you to visit every 3-6 months.
Hormonal changes that occur during pregnancy can worsen diabetic retinopathy, (1) so extra care and follow-ups are needed during pregnancy. Also, people with diabetic eye complications have a risk of kidney complications as well. Therefore, it is prudent to get kidney tests done if you have a diabetic eye disease or vice versa.
Fortunately, regular eye check-ups can detect most of the eye problems very early. The ophthalmologist will use various instruments to thoroughly assess your eye—check your cornea, intraocular pressure, retina, etc. Some of the conditions (dry eye, infections) can only be treated by medicines; others (diabetic retinopathy, cataract) almost inevitably require surgery.
Good sugar and blood pressure control are essential to decrease the risk of eye complications. Eat a diabetes-friendly diet. You should completely avoid smoking, and if you must drink alcohol, do so in moderation. (1) Although a strong evidence is lacking, vitamin D deficiency may have a role in diabetic retinopathy,(2) so ask your doctor for a blood test and if you need a supplement.
- Nentwich MM, Ulbig MW. Diabetic retinopathy-ocular complications of diabetes mellitus. World journal of diabetes. 2015;6(3):489.
- Lee R, Wong TY, Sabanayagam C. Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss. Eye and vision. 2015;2(1):17.
- Skarbez K, Priestley Y, Hoepf M, Koevary SB. Comprehensive review of the effects of diabetes on ocular health. Expert review of ophthalmology. 2010;5(4):557-77.