Diabetic Retinopathy
Diabetic retinopathy is retinopathy (damage to the retina) caused by complications of diabetes mellitus, which can eventually lead to blindness. It is an ocular manifestation of systemic disease which affects up to 80% of all patients who have had diabetes for 10 years or more. With the increase in diabetic cases every year, diabetic retinopathy is now the sixth most common cause of blindness in India. Despite these intimidating statistics, research indicates that at least 90% of these new cases could be reduced if there was proper and vigilant treatment and monitoring of the eyes citation.
  Are the eyes of all diabetics affected?

Eyes of about 80% of the diabetic patients are affected over time. The longer the duration of diabetes greater are the chances of developing retinopathy.
  How can diabetes affect the eye?  

Diabetes causes retinopathy, early droplet type of cataract and makes one more prone to developing glaucoma.
  What is diabetic retinopathy?  

Diabetes in responsible for micro vascular changes all over the body leading to typical kidney or nerve problems etc. Similar changes in vessels of retina produce diabetic retinopathy. In this condition, the retinal blood vessels are affected causing insufficient supply of oxygen and nutrients needed by the retina to remain healthy. There are bleeding spots and deposits of fatty material with swelling of the retina. Thus the retina is unable to transmit visual messages to the brain resulting in low vision or blindness.

How does diabetic retinopathy cause low vision or blindness?

Diabetic Retinopathy can be either Non-proliferative: When the blood vessels leak, macular edema may occur, thereby reducing vision.
Proliferative: When new, weak blood vessels grow or proliferate, bleeding into the vitreous may occur and cause severe visual loss
In moderate cases, the visual loss is due to swelling and bleeding within the retina. But in many cases vision is lost due to severe bleeding inside the eye from the abnormal blood vessels in the retina, leading to blindness. In advanced cases it may be because of tractional retinal detachment 
  What are the symptoms by which diabetic retinopathy can be identified?  
Usually diabetic retinopathy is symptomless. Some may have normal vision till they develop sudden blindness due to bleeding. As there are no symptoms in early stages diabetic retinopathy, it is essential that diabetic patients undergo a routine check-up by an eye specialist every six months.
How is diabetic retinopathy diagnosed?
  1. Retinal Examination:
  2. Fundus Fluorescein Angiography (FFA): In FFA, photographs of the Retina are taken, after injecting a dye in the arm.
  3. Ocular Coherence Tomography (OCT): This advanced imaging modality allows scanning of the retina.

This helps visualize and document the swelling and deposits in the retina and may also reveal the presence of tractional bands.
How is diabetic retinopathy treated?

Early diagnosis of Diabetes Mellitus and effective control of blood sugar through diet, exercise and medication can help reduce your risk of developing these eye problems associated with Diabetes Mellitus.

The treatment of diabetic retinopathy is decided on the basis of the stage of the disease. In the very initial stages, it just requires periodic follow up to look for progression of disease. The ophthalmologist decides when to see a patient next depending upon the severity of changes in the retina.

Later when the disease is more advanced he/she may decide to treat it with one or more of the following options:

Laser Treatment : There are well-defined criteria for laser therapy. Laser therapy is done when there is significant maculopathy, or when there are significant new blood vessels in the retina or iris. Laser treatment is an OPD procedure. After putting anesthetic/numbing drops in the affected eye, the patient is comfortably seated on a stool/chair with chin and forehead stabilized. A contact lens is then inserted in the eye and laser beam is focused onto the retina. The light is absorbed by pigment layer of the retina, where it is converted into heat. Laser photocoagulation helps to preserve vision by preventing new blood vessel formation. It may also help in reducing the swelling of thickened retina in some cases and prevent further deterioration of vision.

Anti-VEGF agents (Lucentis, Avastin, Macugen) : These agents are being used in some selective cases alone or in addition to laser treatment or surgery.

Surgery : Vitrectomy surgery and other additional procedures may be required to manage the complications of diabetic retinopathy, like vitreous hemorrhage, retinal detachment, severe macular edema, etc.

The vitreous is the clear, jelly-like substance that fills the middle of the eye. In some patients, there may be bleeding into the vitreous or the vitreous may pull the retina, reducing vision severely. In such instances a surgical procedure called vitrectomy is performed. The Vitreous is removed during vitrectomy surgery and usually replace by a saltwater solution.

The operation removes any blood or debris (from infection or inflammation) that may be blocking or blurring light as it focuses on the retina. Vitrectomy surgery removes scar tissue that can displace, wrinkle, or tear the retina. Vision is poor if the retina is not in its normal position