Samir G Farah, MD
Assistant Professor of Ophthalmology
St. George Hospital University Medical Center
University of Balamand
How the eye works
When you look at something, light passes through the front of your eye and is focused by the cornea and lens onto your retina. The retina is a delicate tissue that is sensitive to light. It converts the light into electrical signals that travel along the optic nerve to your brain. The brain interprets these signals to “see” the world around you. The retina is supplied with blood by a delicate network of blood vessels. These blood vessels can be damaged by diabetes.
Diabetes and the eye
If diabetes is uncontrolled it can affect the eye in a number of ways:
- Blurring of vision;
- Cataract, when lens of your eye can go cloudy;
- Glaucoma, when the optic nerve is damaged due to high intraocular pressure
The most serious complication of diabetes for the eye is the development of diabetic retinopathy. Types of retinopathy are:
- Background diabetic retinopathy
This is the most common type of diabetic retinopathy. As long as the macula is not affected, vision is normal and you will not be aware that anything is wrong.
- Proliferative diabetic retinopathy
When diabetic retinopathy progresses, it can cause the blood vessels in the retina to become blocked. The retina becomes ischaemic. If this happens the eye is stimulated into growing new vessels, a process called neo-vascularization. This is the proliferative stage of diabetic retinopathy. These blood vessels can bleed very easily.
Most sight-threatening problems caused by diabetic retinopathy can be managed by laser treatment if detected early enough. The aim of laser treatment is to prevent bleeding or the growth of new blood vessels. It is important to remember that laser treatment aims to prevent your vision from getting worse. It cannot make your vision better.
- Diabetic maculopathy
Diabetic maculopathy means that the macula is affected. This may occur either with background, or proliferative retinopathy. If this happens, the central vision will be affected and it will be difficult to see details such as recognizing people’s faces in the distance or seeing details such as small print. However, the vision that allows getting around at home and outside (peripheral vision) is not affected. Treatment can be focal laser or intraocular injected medications.
Important points to remember
- Early diagnosis of diabetic retinopathy is vital.
- Attend your annual diabetic eye screening appointment.
- Don’t wait until your vision has deteriorated to have an eye test.
- Regular retinal screening is key and early detection and treatment can prevent sight loss.
- Tell your endocrinologist if you notice changes to your vision.
- Most sight-threatening diabetic problems can be managed by laser treatment if performed early enough.
- Good control of sugar, blood pressure and cholesterol reduces the risk of diabetes-related sight loss.
- Smoking increases the risk of diabetes-related sight loss.