What is diabetic retinopathy? The most serious eye condition associated with diabetes involves the retina, more specifically the network of blood vessels lying within it. This condition is called as diabetic retinopathy and is the leading cause of visual loss in diabetics. It is graded according to severity and its stages are described as:

Background or non proliferative diabetic retinopathy Blood vessels are mildly affected. Some blood vessels shrink, others grow to form balloon-like sacs which may leak or hemorrhage. In the majority of cases, sight is not seriously affected. However, this is a warning sign that a sight-endangering condition could occur in the future, so more frequent eye exams are required to monitor for further deterioration.

Maculopathy

Involves the central portion of the retina and is the main cause of loss of vision. It may be caused by leakage of fluid or lack of blood supply or both (mixed)

Proliferative diabetic retinopathy Proliferative diabetic retinopathy is the most severe stage and the most threatening to eyesight. It is caused by a lack of oxygen to the eye, which stimulates abnormal blood vessel growth. These vessels are fragile and may rupture causing bleeding and sudden loss of vision. Scar tissue from the ruptured blood vessels may tighten and pull on the retina, detaching it from the inner wall. There is no symptom of pain, and severe loss of sight, even blindness, may result.

Who develop diabetic retinopathy?

What is retinal detachment?

Retinal detachment typically begins with one or more small holes or tears in the retina. These holes are caused by shrinkage of the vitreous--a clear, gel-like body which fills the center of the eye and is attached to the retina. Once a tear has occurred, watery fluid may flow through the tear from the center of the eye underneath the retina weaking its attachment and causing the retina to detach – rather like a wallpaper peeling off a damp wall. When the retina detaches there is a sensation of a veil or curtain coming across the field of vision. Eventually central vision is also lost.

Who is at risk?

Overall retinal detachment is uncommon and affects one person in ten thousand. The condition is most typically found in patients who are nearsighted, have undergone previous eye surgery, experienced eye trauma, or who are have a family history of retinal detachments. Middle-aged and older individuals are at higher risk than the younger population. The condition is also likely to recur in individuals with a previous retinal detachment.

What are the warning symptoms and signs?

The sudden appearance of "floaters" -- floating black dots -- or brief flashes of light in your vision, may indicate the development of a retinal tear. Flashing lights are best seen in the dark, last a few seconds and usually occur in your peripheral (side) vision.

An untreated retinal tear can progress to a retinal detachment. As this occurs, vision is lost in the detached portion of the retina. Some individuals experience the sensation of a veil or curtain coming across their peripheral vision. If it progresses, central vision may be lost and the entire retina may become detached. If left untreated the result may be a total loss of vision in the affected eye.

What is Posterior Vitreous Detachment?

It means separation of the normal vitreous jelly from the retina. This is a fairly common occurrence in most people in the elderly age group. It may occur at an earlier age in myopia, trauma and inflammatory conditions. The separation of vitreous may cause a pull or tug on the retina giving rise to flashing lights. Sometimes it may lead to the formation of retinal breaks. For this reason it is necessary to have a detailed retinal examination whenever one sees new floaters or flashes. If a retinal tear is present urgent Laser treatment is needed to seal the tear before retinal detachment develops

What is the treatment?

Treatment For Retinal Tears

Retinal tears can generally be treated in the clinic using painless, minimally invasive procedures that require no incision.

Laser Photocoagulation An ophthalmic green LASER is used to place spots around the edge of the tear producing scars that seal the edges and in most instances prevents the development of a retinal detachment (fig. 4).

Cryopexy (freezing) Like the laser treatment, cryopexy stimulates scar formation to seal the edges of a retinal tear (fig. 5). Vision is not usually affected by the treatment of a retinal tear, and new floaters may be seen even after treatment. Usually, they will become less noticeable after a few months.

Treatment For Retinal Detachment

Retinal detachment must be repaired surgically. Based on the length of time the retina has been detached, the severity of the detachment and the location of the tear in the retina that caused the detachment, different procedures are used for repair viz: scleral buckling, pneumatic retinopexy and vitrectomy. In some instances, a combination of these procedures is used.

The operation can be done either under local or general anaesthesia.

SCLERAL BUCKLING An incision is made around the eye and fluid that has collected under the retina may be drained. An elastic band is placed upon the outside of the eye, bringing the eye wall into contact with the retina (fig. 7). A gas bubble may also be used. Following this procedure vision usually begins to improve within a few weeks; it may take up to six months for full recovery. Glasses may be needed following the surgery as the operation frequently makes one more nearsighted.

Vitrectomy During this operation the gel-like material in the middle of the eye (the vitreous) is removed. Accumulated scar tissue, when present, is removed. The vitreous cavity is re-filled with a clear liquid, a gas bubble, or other vitreous substitutes like silicone oil. Visual recovery is slow and may take as long as six months. If silicone oil is used, a second surgery to remove the oil is usually needed after a few months.

How much vision can I expect after surgery?

With advances in instrumentation and techniques a good success rate of more than 90% can be achieved after a single operation. Visual recovery depends on how much of the retina has been detached and for how long. Most cases if detected and operated timely recover good vision.

What happens if the detached retina is not put back in place?
Most people will lose all useful vision if no operation is carried out. The success rate and visual recovery also decreases if surgery is delayed. The eye may shrink in size (phthisis) or it may become red, painful and irritable with increase in the intraocular pressure.

AGE RELATED MACULAR DEGENERATION

What is the macula? The macula is a small area at the centre of the retina, which is responsible for fine vision and our ability to percieve colour.

What is macular degeneration? The delicate cells of the macula become damaged and stop working. When this occurs later in life usually after the age of 50, it is called age related macular degeneration (AMD). Broadly it is divided into 2 types: Dry AMD : is the most common form and develops slowly causing gradual loss of central vision.

Wet AMD : Though less common, this is the more severe variety associated with growth of new blood vessels behind the retina. This causes bleeding, leakage of fluid and scarring and may lead to severe vision loss.

What causes AMD and who are at risk?

The exact cause is not known, however a number of risk factors have been identified.

What are the symptoms?

In the early stages the central vision may become blurred or distorted. Straight lines may appear wavy or fuzzy. AMD is not painful. In the advanced stage patients notice a blank patch or a dark spot in the centre of their sight. Reading, writing, and recognizing small objects or faces becomes difficult.

What should I do if I Think I have macular degeneration?

You should consult your eye specialist. If you have AMD in one eye and develop symptoms in the other eye, an emergency appointment should be sought.

Looking at an Amsler grid may help in early detection. The pattern of this grid resembles a checkerboard. You will cover one eye and stare at a black dot in the centre. You may notice that the straight lines in the pattern appear wavy or that some of the lines are missing

A detailed examination with dilated pupils is essential. In some cases, a fluorescein angiogram may be needed.

Fluorescein angiography

Fluorescein angiography is a diagnostic technique that provides information about the blood vessels at the back of the eye. The test is performed by injecting fluorescein dye into a vein in the arm. The dye travels into the blood vessels in the eye and highlights any abnormalities. The passage of the dye is digitally recorded similar to an x-ray film. The images are interpreted by the doctor and from them treatment options are obtained.

The images from the fluorescein angiography test will assist in determining the best treatment for your eye condition. This diagnostic test is commonly used to detect and monitor several eye conditions: age-related macular degeneration (AMD), the effects of diabetes on the eyes, as well as other macular diseases.

Possible side effects of the test

Allergic reactions to fluorescein dyes rarely occur, however one may experience a skin rash, itchy skin, or difficulty in breathing. For this reason this procedure is carried out with anaesthetist backup. If any of these symptoms arise treatment with oral or injectable antihistamines is the usual course of treatment.

Can macular degeneration be treated?

The “Wet” type of AMD is amenable to treatment.

This can be done in some types with a special type of cold laser called Photodynamic therapy (PDT) which helps in ablation of new blood vessels. This can help to stabilize vision and in some cases improve it. More than one treatment may be needed.

Recently a new modality of treatment in the form of injections into the eye (Anti VEGF therapy: Macugen, Lucentis and Avastin injections) has shown a lot of promise. High levels of a specific growth factor occur in eyes with wet AMD and promote the growth of abnormal new blood vessels. The drug injections block the effects of the growth factor. These not only stabilize but have also shown improvement in vision. Multiple injections are usually needed.

How is Dry AMD treated?

Once dry AMD reaches an advanced stage, no form of treatment can prevent visual loss. The AREDS (Age Related Eye Disease Study) found that taking a specific high dose formulation of antioxidants and zinc reduces the risk of developing advanced AMD and associated visual loss.

The specific amounts used by the study researchers were 500 milligrams of Vitamin C, 400 IU of vitamin E, 15 milligrams of beta carotene, 80 milligrams of zinc and 2 milligrams of copper.

The above formulation is not a cure for AMD. It will not restore vision already lost from the disease. It is difficult to achieve the high levels of antioxidants and zinc in the AREDS formulation through diet alone or from common multivitamin tablets.

Will I go blind?

AMD almost never leads to total blindness. Though the central vision is affected, most patients have enough side or peripheral vision to get around and keep his or her independence.