Most persons suffering from diabetes develop changes in the retina over a period of time. This is caused by damage to the small blood vessels (or capillaries) in the retina.
You should consult the doctor treating you for diabetes regularly and follow all instructions regarding diet and medication. It is a fact that only strict control of blood sugar will help minimize damage to the retina. Frequent examination of the retina after full dilation of the pupil can help detect retinopathy early, leading to better treatment outcomes. This retinal examination should be done periodically even if your vision is clear.
Retinal changes are the major problem, but at times diabetes can also cause a rise in eye pressure (glaucoma), clouding of the lens (cataract), and weakness of the optic nerve or eye muscle. Cataracts often occur at a younger age in diabetic patients. Glaucoma can cause damage to the optic nerve. In fact diabetes is one of the several possible causes of glaucoma.
Damage to the small vessels of the optic nerve can affect vision, and weakness of the eye muscles may cause double vision. A diabetic is also more likely to develop sudden vision loss due to occlusion of the retinal vessels (branch or central retinal vein occlusion), bleeding in the vitreous cavity, detachment of the retina, or infections of the cornea and vitreous.
Swelling (edema) in the central part of the retina (macular edema) can cause blurring of fine vision. Fragile new blood vessel sprouts may break and bleed into the interior of the eyeball, causing blurring of the entire field of vision. In the early stages of the disease the vision remains good therefore, the disease may escape notice. That is why it is essential to have regular retinal examinations if you know that you have diabetes.
Swelling of the central part of the retina may be controlled with limited laser treatments. Sometimes one laser session will suffice, though some patients require several sessions. Abnormal blood vessel sprouts require extensive laser treatment involving 2,000 to 3,000 laser spots, i.e., three or more laser sessions. More acute problems with severe bleeding or retinal detachment require surgery such as scleral buckling or vitrectomy or both.
Normally the retina is firmly attached to the back of the eyeball. If it becomes detached, the eye loses vision. This is a rare disease occurring in about one person out of 10,000, each year. The immediate cause is usually a hole in the retina. It may be due to injury or surgery, but is usually due to weakness of the retina. This is sometimes called degeneration.
The surgery may be done under general anaesthesia (you will be sound asleep) or local anaesthesia (you will be awake but an injection will prevent any pain). The retina is reattached by freezing (cryosurgery) and with the placement of a permanent silicon patch (buckle) on the wall of your eyeball. The external stitches will melt away and do not have to be removed. Usually the eye responds to one operation; occasionally, additional surgery may be required. The eyelashes are cut before surgery but they always grow back. You will probably spend one or two nights in the hospital after the operation. Normally, only the operated eye is bandaged but, sometimes, both eyes may be bandaged for a few days. Most patients can return to work in four to five weeks.
You must stay at home for at least three weeks, traveling should be avoided except to visit the doctor. After surgery you will be given written instructions regarding medication and precautions to be taken. You should carefully observe these instructions. You may be advised to lie on your side or stomach while sleeping or resting.
In most cases (85%) the retina can be reattached with a single operation. Occasionally additional surgery is necessary; this brings the final cure rate up to approximately 95%. The final degree of clarity of vision will not be known for three months. If you had lost your reading vision before surgery, you should find considerable improvement but probably not 100%. If your reading vision was not lost before surgery, good vision will be retained (after convalescence) in more than 90% cases. In 5% cases the retina may not re-attach, necessitating further surgery.
Your vision will be blurred. The eye will be painful, red and swollen and there may be some mucus discharge. The pupil will be large and you may see double. These side effects are usually temporary and last only a few weeks. In many cases the eye will become more near-sighted; this can be corrected with spectacles.
Over 90% cases have no significant complications. Occasional problems include bleeding or infection or re-detachment. Very rarely such complications could lead to the loss of all vision. Anesthesia-related complications are also rare; the anesthetist will discuss these with you.
If the retina remains attached for three months after surgery, the chance of recurrence is only 10%. If the retina of your other eye appears normal at this time, the chance of developing a detachment later on is approximately 12% in the eye that has not been operated.
In some cases the retina is more fragile and prone to formation of holes or breaks. If these are detected and sealed in the early stages by laser or cryosurgery, retinal detachment can be prevented. People who are likely to develop retinal detachment should have periodic examinations done after dilation of the pupils. Some of the situations where this is desirable are:
This is a very delicate operation performed with an operating microscope and special needle-sized instruments. The most common indication for this operation is removal of the vitreous, which has lost its transparency and, therefore, has become an obstacle to the incoming light. In this surgery most of the non-transparent vitreous is removed and replaced with a clear solution. Vitrectomy may also be used to remove the pulling forces of the vitreous, which may have led to detachment of the retina. This operation may also be used to remove blood clots, infectious material, cataract, foreign bodies, and abnormal membranes from the interior of the eyeball. Sometimes it is done for diagnostic purposes for diseases of unknown origin. Occasionally it may be necessary to inject air, gas, or silicone oil into the eye after removing the vitreous gel.
The surgery may be done under general anesthesia (sound asleep) or under local anesthesia (you are awake but feel no pain). The operation takes two to four hours. Usually one operation is sufficient, occasionally additional surgery may be required. The eyelashes are cut but they always grow back. Most patients stay in hospital for one or two days; longer hospitalization may sometimes be necessary. A face-down position for sleeping may be suggested for several days. The operated eye will be bandaged for one day. Occasionally both eyes may need to be bandaged to ensure complete ocular rest.
For the first two weeks you should rest at home. Travelling should be avoided except to see the doctor. If gas has been injected into the eye, you should avoid air travel for several weeks until specifically authorized by the doctor. Postoperative instructions will be given to you at the time of discharge and these should be strictly followed. Most patients are able to return to their routine in four weeks.
The vision improves to some degree in 90% of simple vitrectomy cases. In difficult cases however, improvement is seen in approximately 60% of the cases while in others it may remain the same or even decrease. The final degree of clarity of vision is usually not evident for about three months. How much vision a patient will ultimately have is difficult to predict in individual cases. Patients are usually able to see large objects but fine vision and reading vision may not improve.
'Cryo' means extremely cold or freezing. This operation employs a delicate instrument that freezes small spots which are transformed into pinpoint scars that strengthen the retina. The temperature required for cryosurgery is approximately minus 70 degrees centigrade.
Generally patients can return to their normal routine the following day. But they are advised to relax on the day of surgery. In cases where there has been a tearing of the retina, the surgeon may ask patients to limit their activities for at least ten days. The restrictions may include the following:
Fluorescein and indocyanine green angiography are tests that use special cameras to photograph the structures in the back of the eye. These tests are very useful for locating the damage to the blood vessels that nourish the retina (light sensitive tissue) and in turn, checking on the health of the retina itself. In both tests, a colored dye is injected into a vein in the arm of the patient. The dye travels through the circulatory system and reaches the vessels in the retina and those of a deeper tissue layer called the choroids. Neither of the tests uses any harmful forms of radiation.
Fluorescein is a yellow dye, which glows in visible light. Indocyanine is a green dye that fluoresces with invisible infrared light; it requires a special digital camera sensitive to these light rays This indocyanine green angiography helps your doctor make the correct diagnosis and plan the best course of treatment especially in diseases like age-related macular degeneration (AMD).
Both fluorescein angiography and indocyanine green angiography are considered very safe and serious side effects from these tests are uncommon. However, there is the possibility that a patient may have a reaction to the dyes. While fluorescein contains no iodine and is safe in patients known to be allergic, indocyanine green is currently formulated with iodine and should not be used in individuals with any known allergies. Some people may experience slight nausea after the dye injection, but the feeling usually passes quickly.
Patients who are allergic to the dye can develop itching and a skin rash. These symptoms generally respond quickly to oral medications such as anti-histamines or steroids. Very rarely, a sudden life-threatening allergic reaction called anaphylaxis can occur. This condition requires medical treatment.
There is also the possibility of an infiltrate of the dye into the skin at the injection site; this may cause some discomfort or discoloring of the skin for several days. The fluorescein dye will turn the patient's urine orange and may slightly discolor the skin as well for a brief period. Your physician can explain the individual risks of these procedures for certain patients, including pregnant women.