Eye disease



Eye disease (retinopathy) is a possible complication of diabetes, known as diabetic retinopathy.

Diabetic retinopathy generally has no early warning signs and may surface suddenly. Sometimes, the person affected will have blurred vision, which deteriorates and improves during the course of a day. "Retinopathy" is medical term describing the damage to the tiny blood vessels (capillaries) that nourish the retina. The retina is located at the back of the eye and it captures light and relays the information to the brain. The tiny blood vessels are adversely affected by high blood sugar associated with diabetes.

In severe cases, blood vessels may bleed causing haemorrhage, and vision may become blurred. Tiny specks of blood, called "floaters", will be floating in the affected person's vision field, and may disappear sometimes. However, they may be followed by greater leakage of blood, and they may clear soon or may not clear even for days and months, and may require treatment and control of diabetes to reduce their impact on the vision.

Signs & symptoms
As already indicated, at an early stage, diabetic retinopathy can not be noticed though the deterioration may be taking place. At its early stage, vision continues to be normal without manifestation of any sign or symptom while the complication continues to advanced stage. Some signs and symptoms of diabetic retinopath include:


 * Dark streaks or red films blocking the vision,
 * Blurred vision,
 * A dark or vacant spot in the center of vision,
 * Tiny specks floating in the vision - looks like spiders or cobwebs sometimes,
 * Difficulty in adjusting from dim light to dark light and vice versa, and
 * Difficulty in seeing during night,

Risk factors
Persons with diabetes have a higher risk of retinopathy irrespective of the type of diabetes, type 1 diabetes or type 2 diabetes. The risk increases longer a person has diabetes. There are also few other contributing factors which increases the risk of diabetic retinopathy. Some of these factors include poorly controlled levels of blood sugar, untreated high blood pressure, high blood cholesterol, and pregnancy.

Complications
In certain cases of diabetic retinopathy, blood vessels on the retina are damaged, and the retina manufactures new blood vessels which are abnormal. The new blood vessels do not supply the retina normal blood and generate other complications. There are three major complications of diabetic retinopathy:


 * Vitreous hemorrhage: In the context of eyes, vitreous, mainly composed of water and comprising around 2/3 of the volume of the eye, is a thick and transparent substance that fills the center of the eye. It gives the eye its form and shape. The new blood vessels bleed (hemorrhage) and blood spills into the vitreous. If the amount so spilled into the vitreous is small, the person affected may see and few dark spots or floaters may appear in the line of vision. However, in severe cases, the blood so spilled may fill the the vitreous cavity completely, and the vision may be completely blocked. The blood may clear over a period of time (of few weeks or month) and the previous vision may be restored, and vitreous hemorrhage by itself may not cause permanent loss of vision unless accompanied by damage to retina.


 * Traction retinal detachment: If the growth of new blood vessels are not stopped at an early stage, their growth may be accompanied the growth of scar tissues. Thees scar tissues sometimes shrink and shrinking may pull the retina away from the black wall of the eye. This causes blurred or blank vision in the field of vision, and sometimes may even cause complete loss of vision.


 * Neovascular glaucoma: The new blood vessels in retina and vitreous may continue to grow accompanied by similar growth of new blood vessels on the iris, which constitutes the most visible part of the eye. This interferes with the normal flow of fluid out of the eye causing pressure build up in the eye. This causes neovascular glaucoma, which is a serious complication of diabetic retinopathy. Neovascular glaucoma can cause damage to optic nerves and may fatally damage the eye.

Research
In May 2007, researchers from the Pennsylvania State College of Medicine in Hershey, PA presented study results that indicate that insulin injected under the conjunctiva (the membrane covering the eyeball) may treat early diabetic retinopathy. The treatment has so far only been tested in rats.