Detached and torn retina
Retinal detachment will affect 1 in 10 000 people each year. It is a serious eye problem that may occur at any age although it is more common in middle-aged or older individuals. Nearsightedness and a family history are additional risk factors. Blunt injuries may also cause detachment of the retina. Left untreated, retinal detachment ultimately leads to loss of vision in the vast majority of cases.
The retina is a thin, transparent tissue of light-sensitive nerve fibers and cells. It lines the inside of the eyeball, and like the film in a camera, is responsible for the image one sees.
Causes and symptoms
Most retinal detachments are caused by the presence of one or more small tears or holes. Normal ageing can cause this, but more often shrinkage of the vitreous gel, which fills the eye, is responsible for the tears.
The vitreous is firmly attached to the retina in several places. As the vitreous shrinks, it may tear the retina, leaving a hole. Fluid may then seep through this hole, separating the retina from the layers beneath it and severely impairing its function.
It must be noted that there are some retinal detachments which are caused by other diseases in the eye such as tumours, severe inflammations, etc. No holes or tears are present in such cases, and treatment of the underlying condition is required to reverse the detachment.
Some people may see floaters and flashes of light in their field of vision. This usually does not indicate serious trouble, but if these symptoms are of sudden onset, it may be as a result of a fresh tear in the retina. Detailed examination of the inside of the eye by your ophthalmologist is necessary to see if tears are present. A fresh retinal tear is often treatable before it causes detachment.
Some detachments may begin without noticeable floaters or flashes. In these instances, patients may notice a wavy or watery quality in their overall vision or the appearance of a dark shadow in some part of their side vision. Further development of the detachment will blur central vision and cause significant sight loss or even blindness unless the detachment is repaired.
A few detachments may occur suddenly, with the patient experiencing a total loss of vision in the affected eye. Similar rapid loss of vision may also be caused by bleeding into the vitreous gel, which sometimes happens when the retina is torn.
Detection and diagnosis
A detached retina cannot be viewed from the outside of the eye. If symptoms are noticed, an ophthalmologist should be visited as soon as possible. Special instruments are used to examine the inside of the eye in detail.
If the retina is torn but not yet detached, it may be prevented by prompt treatment. This is usually done as an office procedure with laser. Once the retina becomes detached, it must be surgically repaired. Successful reattachment of the retina consists of sealing the retinal tear and preventing the retina from pulling away from the back of the eye again. There are several surgical procedures that can be used, and selection of technique depends on the nature of the detachment.
Laser photocoagulation – When new tears are found with little or no detachment as yet, they can be sealed with laser light. The laser places small burns around the edge of the tear, causing a firm scar that seals the edges of the tear and preventing fluid to leak in under the retina. This kind of laser treatment requires no anaesthesia or surgical incision and is done in the ophthalmologist’s office.
Surgical repair – Once a significant amount of fluid has collected under the retina, surgery is required. Each operation differs according to the severity and type of detachment, but all have the common goal of pressing the wall of the eye and the retina together until scarring has sealed the holes firmly. Sometimes fluid is drained from under the retina to allow it to settle back into position. Often a silicone band or pressure pad is placed outside the tear to gently press the wall of the eye to the retina. Sometimes, gas is injected to press the retina from the inside as well.
In more complex detachments, it may be necessary to use a technique called vitrectomy. In this operation the vitreous gel is removed from inside the eye, removing shrunken bands of gel that contribute to the detachment. In some difficult cases the retina may have to be held in place by temporarily filling the eye with a gas mixture, or with liquid silicone.
More than 95% of retinal detachments can be repaired with modern surgical techniques. More than one operation may be required in 15 – 30% of cases.
If the retina is reattached, the eye will regain some degree of sight, and blindness will have been prevented. However, the degree of vision which finally returns about 6 to 18 months after successful reattachment, depends on a number of factors. In general, there is less visual recovery in long-standing detachments, or if there is fibrous growth on the retina. Approximately 40% of patients achieve excellent vision. The remainder attain varying degrees of reading and/or navigational vision. In a small group of unfortunate patients, the retina continues to contract due to shrinking membranes, and fails to reattach, leading to blindness.
Depending on the nature of the detachment, the expected duration of the surgery and the health of the patient, retinal operations are done under either local or general anaesthesia, mostly the latter. Usually patients can go home directly after the operation, or at most an overnight stay in hospital is required. Eye drops are usually the only medication used afterwards, except for the occasional use of painkillers for the first day or so.