Retinal Diseases

Retinal diseases specifically affect the retina — a layer of tissue at the back of the eye that is responsible for vision. These diseases can affect the retina, the macula (area of central vision), or the fovea at the center of the macula. Many retinal diseases share common symptoms and treatments, but each has unique characteristics.


Diagnosis

The diagnosis of a retinal disease is usually made based on a thorough eye exam by an ophthalmologist. An ophthalmoscope allows the doctor to view the inside of the eyes in three dimensions. The ophthalmologist looks for presence of abnormalities anywhere in the eye. Additional tests may be done to determine the location and extent of the disease.

Amsler Grid Test
The physician may use a printed grid to test clarity of central vision. The doctor will ask if the lines of the grid seem faded, broken or distorted, and will take note of where the distortion occurs on the grid. By evaluating the location of the distortion, the physician will better understand the extent of retinal damage caused by disease.

Optical Coherence Tomography (OCT)
Similar in principle to ultrasonography, OCT relies on light waves slicing through tissue layers in the back of the eye. They produce a "backscattering" that converts into high-resolution, cross-sectional images of the retina, macula and optic nerve. Particularly useful in investigating abnormal tissue, With this new medical imaging technology, clinicians have another painless, precise diagnostic tool.

Fluorescein Angiography
To get more information about a suspected retinal disease, the doctor may use fluorescein angiography to identify leaking blood vessels. First, the doctor injects dye into a vein in the patient's arm. As the dye circulates through the bloodstream and eventually to the eye, the blood vessels in the retina stand out as bright yellow when observed with a special blue light. A camera takes flash photographs of the eye every few seconds for several minutes. The images help identify the blood vessels, new abnormal blood vessels and subtle pigmentation changes in the back of the eye.

Indocyanine Green Angiography (ICGA)
Another type of angiography of the vessels in the eye is ICG. ICG is a dye that lights up when exposed to infrared light. Infrared light is used to take pictures of the back of the eye visualizing retinal blood vessels, and the deeper, harder to see choroidal blood vessels.

Ultrasound
An ophthalmologist can usually find evidence of retinal disease with the ophthalmoscope, but occasionally blood or other problems in the eye prevents a clear view of the retina. In these cases, the doctor may use ultrasound, a painless test that uses sound waves to get a precise picture of the retina. Ultrasound is also used to measure the size of growths in the back of the eye.


Treatment

The goal of many treatments is to stop further progression of the disease. In most cases, the damage that has already occurred cannot be reversed, making early detection very important for vision preservation.

The physician will recommend one of the following treatments:

Photocoagulation
In photocoagulation, the surgeon creates small burns in the retina using a high energy laser. For a retinal tear or hole, the goal is to create scar tissue around the tear, which usually holds the retina to the underlying tissue. For diabetic retinopathy, the burns help seal off the abnormal blood vessels, stopping leakage of blood and fluid into the eye.

Creating burns on the retinal surface will cause blind spots, but photocoagulation is nearly always done on the peripheral surface of the retina. Any blank spots or loss of vision will occur in the peripheral vision, leaving central vision intact.

Panretinal Photocoagulation
Panretinal photocoagulation is a procedure used for proliferative diabetic retinopathy where abnormal new blood vessel growth is diffuse and causes bleeding into the vitreous. With this technique, the retina (except the macula, responsible for central vision) is treated with laser burns. These burns cause the new blood vessels to shrink and disappear, but the burns cause some peripheral vision loss. By sacrificing some side vision, surgeons can preserve as much central vision as possible.

Cryopexy
In cryopexy, the surgeon uses intense cold to freeze the area around a retinal tear or hole. This causes scarring which seals the hole and holds the retina to the underlying tissue to prevent fluid from passing through the tear, leading to retinal detachment.

Pneumatic Retinopexy
Pneumatic retinopexy is a treatment for retinal detachment. This surgery can be performed on uncomplicated retinal detachments with tears located in the upper half of the retina. First, cryopexy is performed around the retinal tear to seal it off. A bubble of gas is injected into the vitreous cavity. The bubble expands over the next few days, sealing the retinal tear, and causing the retina to reattach itself to the wall of the eye. Since the bubble must push against the tear, it may be necessary for patients to keep their head in a cocked position following surgery, depending on where the tear(s) is. Until the gas is gone from the eye (two to eight weeks), the patient must avoid lying or sleeping on his or her back to guard against cataract formation or a sudden increase in eye pressure.

Scleral Buckling
Scleral buckling is one of the most common surgeries for repairing retinal detachment. The surgeon sews buckling material (solid or spongy silicone) to the eye wall causing localized indenting of the sclera (eyeball) under the retinal tears. This indent, or buckle, closes the tear and changes the circumference of the eyeball, thereby preventing further pulling and separation. This procedure successfully repairs retinal detachment in more than 90 percent of cases, but preservation of vision depends on how the macula was affected before surgery. In some cases, some vision may be lost due to wrinkling or puckering of the macula. See Epiretinal membrane.

Vitrectomy
When the back part of the eye is entered to treat a problem, the surgery is referred to as vitrectomy. During this procedure the eye is entered through tiny incisions and the vitreous gel is removed, followed by additional surgical steps, as necessary. Sometimes cloudy vitreous is removed as the only surgical goal. In other instances, peeling of scar tissue, laser photo coagulation, scleral buckle placement, gas injection or other steps are undertaken.