Diabetic Retinopathy

What is Retina?

The retina is like the film of a camera. It is the seeing tissue. It has two parts, the Peripheral Retina & Macula (Central Retina). Macula is responsible for clarity and quality of vision. Peripheral Retina enables us to have panoramic view. Macula has a large number of capillaries (tiny blood vessels).

What is Diabetic Retinopathy?

Diabetes Mellitus is a disorder of sugar/ glucose metabolism in the human body in which the body cannot utilize it for energy. The extra unutilized sugar acts like poison for the whole body affecting every organ especially the eyes, heart, kidney and brain. Retina needs a lot of oxygen and has plenty of blood vessels, so it gets affected and the condition is known as DIABETIC RETINOPATHY. It results in loss of vision.

Stages of Diabetic Retinopathy:

There are mainly 2 stages of diabetic retinopathy;

• Background or Non Proliferative Diabetic Retinopathy (NPDR) or
• Proliferative Diabetic Retinopathy (PDR). Diabetic Maculopathy (DM) can be present in either stage and be responsible for loss of vision.

Non Proliferative Diabetic Retinopathy (NPDR)

This is the earliest stage where blood vessels in the retina leak fluid, sometimes fat and blood into retinal tissue.

This results in development of Micro aneurysms, edema (swelling) and hard exudates in retina. Many people with NPDR have normal vision and the treatment consists of STRICT CONTROL of Diabetes and associated systemic illnesses. Periodic follow up examinations every year is very important to catch the disease at the earliest.

Photograph showing Retinal haemorrhages and microaneurysm in a patient of NPDR

Diabetic Maculopathy (DM)

• Macular Edema: Due to the fluid leaked from the capillaries, there is a swelling at the macula which leads to impairment of vision from mild to severe degrees.
• Macular Ischemia occurs when small blood vessels (capillaries) close at macula which leads to drop in vision.

Investigations

FFA (Fundus Fluoresceine Angiography): Fluoresceine dye is injected in the vein and photographs are taken of both retina with FUNDUS CAMERA. It shows the structure of retinal vessels, leakages and perfusion status of retina.

OCT (Optical Coherence Tomography)

Provides additional information regarding thickness and structure of macula and relationship of vitreous fluid to macula.

Treatment of Diabetic Maculopathy:

• In addition to proper management of diabetes, treatment consists of laser treatment to macula and/ or intravitreal injection of steroid or anti-VEGF drugs like Avastin, Macugen or Lucentis.
• Occasionally, vitreous surgery may help in treatment.

Proliferative Diabetic Retinopathy PDR):

Closure of multiple capillaries (tiny blood vessels) leads to growth of abnormal new blood vessels on the surface of retina and / or optic nerve (neovascularisation). These new vessels are weak and bleed easily, leading to vitreous hemorrhage. They are often accompanied by scar tissue which can lead to tractional retinal detachment. When the macula is detached, vision can be lost.

Treatment of proliferative Diabetic Retinopathy:

It consists of 2-3 sittings of laser treatment to entire retina except the optic disk and macula. Also called Pan Retinal Photocoagulation (PRP)

Advanced Proliferative Diabetic Retinopathy:

Some patients present at this stage, some patients worsen despite adequate laser treatment and may have vitreous hemorrhage, retinal detachment and Neovascular Glaucoma. These patients may have very poor vision.

Treatment:

PRP laser if possible and Vitreous surgery to remove scar tissue. Usually, the results are encouraging.

Who is at RISK of developing Diabetic Retinopathy?

Diabetic Retinopathy is the most leading cause of preventable blindness after cataract. Risk Factors are:

• Duration of diabetes: Longer the duration, more the risk.
• Type of control of diabetes.
• High blood pressure and smoking.

What happens during you examination?

Your pupils are dilated with eye drops and retina is examined by special equipments like Indirect Ophthalmoscope and Slit Lamp Bio Microscope.

Important things to prevent blindness if you are diabetic

• Strict control of blood sugar, blood pressure and cholesterol.
• Regular visits for checking retina, even if you do not have problem with your vision.
• Timely treatment of lasers or vitreous surgery to prevent blindness.