The retina is a thin, light–sensitive tissue that covers the inside back portion of the eye. In most cases retinal detachment is caused by the presence of one or more small tears or holes in the retina. These tears may be due to thinning of the retina with age, but more often they are caused by shrinkage of the vitreous, a clear, gel–like substance that fills the inside of the eye. The vitreous helps maintain the shape of the eye and allows light to pass through to the retina.
RetinaThe vitreous is firmly attached to the retina in several places. As people get older, the vitreous shrinks and often separates from the retina. By the age of 50 years the vitreous has separated from the retina in about 50% of all people. As the vitreous shrinks, it may pull a piece of the retina away with it, leaving a tear or hole in the retina. Abnormal growth of the eye (sometimes a result of near–sightedness), inflammation or injury may also cause the vitreous to shrink.
Retinal TearWhen a retinal tear is present, watery fluid from the vitreous space may pass through the hole and flow between the retina and the back wall of the eye. This separates the retina from the back of the eye and causes it to detach. The detached portion of the retina will not work properly, and there will be a blur or blind spot in the vision. In some cases retinal detachment is caused by other diseases of the eye, such as tumors, severe inflammations and complications of diabetes mellitus. In these cases there are no tears or holes in the retina, and treatment of the disease that caused the detachment is the only treatment that may correct the detachment.
Symptoms of Retinal Detachment
Retinal DetachmentIn some cases the sudden appearance of spots or flashes of light may indicate substantial shrinkage of the vitreous, with tears in the retina. In other cases the person may notice a wavy or watery quality in their overall vision or the appearance of a dark shadow in some part of their peripheral vision. Further development of the retinal detachment will blur the central vision and create significant loss of vision unless the detachment is repaired.
Occasionally, retinal detachment occurs suddenly, and the person will experience a total loss of vision in one eye. Similar rapid loss of vision may be caused by bleeding into the vitreous, which may happen when the retina is torn.
Detection and Treatment of Symptoms of Retinal Detachment
A detached retina cannot be seen from the outside of the eye. Therefore, if symptoms are noticed, an ophthalmologist – a medically trained eye doctor–should be visited as soon as possible. People who are very near–sighted or who have a family history of retinal detachment should have regular eye examinations by an ophthalmologist so that any changes in their retina or vitreous may be detected early and retinal detachment prevented.
If the retina is torn, prompt treatment may prevent retinal detachment from developing. If there is little or no retinal detachment, the tears are sometimes sealed with a laser light (laser photocoagulation). The laser places small burns around the edge of the tear. These produce scars that seal down the edges of the tear and prevent fluid from passing through. Laser photocoagulation is often done as an outpatient procedure, without the need for admission to hospital, and requires no surgical incision. Freezing the back wall of the eye behind the retinal tear (cryopexy) will also stimulate scar formation and seal down the edges of the tear. Cryopexy is often done as an outpatient procedure, but local anesthesia is needed to numb the eye.
If the retina is detached, it must be repaired surgically by an ophthalmologist. Retinal detachment can be repaired in over 90% of cases, occasionally, more than one operation may be needed. Sometimes fluid must be drained from under the retina to allow the retina to settle back onto the back wall of the eye. Often a silicone band or pressure pad is placed on the outside of the eye to gently push the back wall against the retina. Either cryopexy or a laser, or the heat of diathermy (an electric current applied through a needle) is used to produce a scar to seal the retinal tear.
In more complex cases it may be necessary to use a technique called Vitrectomy. The ophthalmologist cuts the vitreous away from the retina and removes the vitreous from the eye. If the retina is severely shrunken and puckered, the ophthalmologist temporarily fills the vitreous cavity with air or gas to push the retina back against the wall of the eye. Eventually, clear fluid from the blood seeps into the vitreous cavity to fill it permanently.
Approximately 40% of people with successfully repaired retinal detachment achieve excellent vision within 6 months of surgery. In general, the results are not as good when the retina has been detached for a long time or when there is a fibrous growth on the surface of the retina. The remaining 60% of people attain various degrees of reading or traveling vision. Unfortunately, because of continuous shrinkage of the vitreous and the development of fibrous growths, the retina cannot always be re–attached. In such people the eye will continue to lose sight and will ultimately become blind.