- What are the effects of diabetes on the eye?
In individuals with diabetes, due to impaired insulin function, the body cannot properly use the sugar absorbed from food, leading to elevated blood glucose levels. If this persistent high blood sugar is not controlled, it can eventually cause long-term complications affecting the eyes, kidneys, and the nervous system (both peripheral and autonomic).
According to recent data, Turkey has the highest prevalence of diabetes among European countries, and the rate continues to rise rapidly. Consequently, this increasing frequency of diabetes has made diabetes-related eye complications a condition that ophthalmologists encounter very often.
The most critical and undoubtedly the most detrimental effect of diabetes on the eye is damage to the retina — the layer containing the cells responsible for vision. The retina functions like a satellite dish that receives light signals and transmits them to the brain.
The harmful effects of diabetes on the retina occur when small blood vessels become damaged as a result of prolonged high blood sugar levels. Diabetic retinal damage typically develops in two main stages.
In the first stage — the early phase of the disease — the effects on the retina are limited. At this point, small hemorrhages and fluid leakage from tiny damaged vessels may be seen within the retinal tissue. During this stage, the patient may not notice visual symptoms, or vision loss may progress slowly enough that daily activities are not yet affected.
In the second, more advanced stage, the damage is no longer limited to the retina itself. Due to vascular deterioration, abnormal new blood vessels begin to grow on the surface of the retina and extend into the vitreous cavity. These newly formed vessels are structurally fragile — they leak easily and are prone to bleeding into the eye. If not treated appropriately, these abnormal vessels can pull the retina away from the inner wall of the eye, leading to a condition known as retinal detachment. In this advanced stage, severe and often irreversible vision loss may occur.
At both stages of diabetic eye disease, leakage from blood vessels can cause fluid accumulation in the macula — the central part of the retina responsible for sharp vision. This condition, known as diabetic macular edema, may lead to visual impairment even in the early phase of the disease.
Diabetes affects not only the retina. It can also lead to dry eye disease, characterized by qualitative and quantitative abnormalities in tear production. Corneal disorders are also commonly seen. Cataracts develop more frequently and at earlier ages in diabetic patients. Additionally, especially in advanced diabetes, postoperative complications after cataract surgery are more common.
- How can it be determined whether diabetes has affected the eyes?
Comprehensive eye examinations, including dilated fundus evaluation, can detect whether diabetes has caused any adverse effects on the eyes. As the saying goes, the eyes are the mirror of the heart — they never lie.
- Can diabetic patients prevent eye complications with proper care?
Yes, it is certainly possible to prevent or delay these complications. What we emphasize to our patients is that diabetes is a systemic disease that affects the entire body.
For this reason, regular follow-up by an endocrinologist or internal medicine specialist is crucial. Adherence to the treatment and lifestyle recommendations provided by these physicians greatly supports the effectiveness of eye-related therapies. Lifestyle modification is one of the most important components. In all types of diabetes, the cornerstones of treatment are patient education, medical nutrition therapy, and regular exercise.
- How often should diabetic patients have eye examinations?
In individuals with type 1 diabetes, eye examinations should begin five years after diagnosis. For those with type 2 diabetes, an eye examination should be performed at the time of diagnosis and repeated annually thereafter. If diabetic eye complications are already present, the frequency of these examinations may need to be increased depending on disease progression.
- How are the eye complications of diabetes treated? Can the damage be reversed?
There are several highly effective treatments available that ophthalmologists use to manage diabetic retinal complications.
The main treatment methods for diabetic retinal disease can be categorized into three groups: laser therapy, intraocular drug injections, and eye surgery.
Laser treatment is used to reduce vascular leakage or to regress abnormal vessel growth in the retina, particularly when fluid accumulation threatens central vision in the macula region.
In more advanced stages of proliferative diabetic retinopathy, when persistent vitreous hemorrhage or tractional changes caused by fibrous tissue occur, a surgical procedure called vitrectomy is performed to clear these opacities and restore retinal structure.
In recent years, intravitreal injections of anti-VEGF medications — drugs that suppress abnormal blood vessel growth and leakage — have become a common and effective treatment option.