Surgeries for Retinal Detachment

Retinal Detachment:

A retinal detachment is an eye condition involving separation of the retina from its attachments to the underlying tissue within the eye. Most retinal detachments are a result of a retinal break, hole, or tear. Retinal detachments of this type are known as rhegmatogenous retinal detachment. These retinal breaks may occur when the vitreous gel pulls loose or separates from its attachment to the retina, usually in the peripheral parts of the retina.

Once the retina has torn, liquid from the vitreous gel can then pass through the tear and accumulate behind the retina. The buildup of fluid behind the retina is what separates (detaches) the retina from the choroid and retinal pigment epithelium (lining tissue) in the back of the eye. As more of the liquid vitreous collects behind the retina, the extent of the retinal detachment can progress and involve the entire retina, leading to a total retinal detachment. A retinal detachment almost always affects only one eye at a time. The second eye, however, must be checked thoroughly for any signs of predisposing factors or existing retinal tears or holes that may lead to detachment in the future.

Why is it mandatory to treat a retinal detachment?

A tear or hole of the retina that leads to a peripheral retinal detachment causes the loss of side (peripheral) vision. Almost all of those affected will progress to a full retinal detachment and loss of all vision if the problem is not repaired. The dark shadow or curtain obscuring a portion of the vision, either from the side, above, or below, almost invariably will advance to the loss of all useful vision. Spontaneous reattachment of the retina is rare.

Early diagnosis and repair are urgent since visual improvement is much greater when the retina is repaired before the macula or central area is detached. The surgical repair of a retinal detachment is usually successful in reattaching the retina, although more than one procedure may be necessary. Once the retina is reattached, vision usually improves and then stabilizes. Successful reattachment does not always result in normal vision. The ability to read after successful surgery will depend on whether or not the macula (central part of the retina) was detached, the extent of time that it was detached and whether any scar tissue developed related to the detachment or the surgery.

Treatment for Retinal Detachment

 Retinal holes or tears can be treated with laser therapy or cryotherapy (freezing the retina or cryopexy) to prevent their progression to a full-scale detachment. Many factors determine which holes or tears need to be treated. These factors include the type and location of the defects, whether pulling on the retina (traction) or bleeding is involved, and the presence of any of the other risk factors discussed above. Three types of eye surgery are done for actual retinal detachment: vitrectomy, scleral buckling, and pneumatic retinopexy.

Vitrectomy

Pars plana vitrectomy (PPV or vitrectomy) is today the most common surgery performed for a retinal detachment. Vitrectomy surgery is performed in the hospital under general or local anaesthesia. Small openings are made through the sclera to allow positioning of a fibreoptic light, an irrigation system, a cutting source (specialized scissors), and delicate forceps. The vitreous gel of the eye is removed to reduce or eliminate the pulling forces of the vitreous (traction) on the retina. Laser or cryotherapy (freezing) is used to treat the retinal tears or holes, and the vitreous is replaced with a gas to refill the eye and reposition the retina. The gas eventually is absorbed and is replaced by the eye’s own natural fluid. This procedure may require special positioning of the patient’s head (such as looking down) in the postoperative period so that the bubble can rise and better seal the break in the retina. If a gas is used that is absorbed very slowly, the patient may have to walk, eat, and sleep with the head facing down for one to four weeks to achieve the desired result.

In the past, vitrectomy was reserved only for certain complicated or severe retinal detachments, such as those that are caused by the growth of abnormal blood vessels on the retina or in the vitreous, as occurs in advanced diabetes; retinal detachments associated with giant retinal tears; vitreous haemorrhage (blood in the vitreous cavity that obscures the surgeon’s view of the retina); extensive tractional retinal detachments (pulling from scar tissue); membranes (extra tissue) on the retina; or severe infections in the eye (endophthalmitis).

In complex cases today, a scleral buckle (see below) is often also performed together with the vitrectomy. In more complicated cases, a silicone oil maybe placed in the vitreous cavity instead of a gas. This oil must be removed at a later date.

Scleral buckle surgery

For many years, scleral buckling was the standard treatment for detached retinas. It is still used in many cases today. The surgery is done in a hospital operating room with general or local anaesthesia. Some patients stay in the hospital overnight (inpatient), while others go home the same day (outpatient). The surgeon identifies the holes or tears either through the operating microscope or a focusing headlight (indirect ophthalmoscope). The hole or tear is then sealed, either with diathermy (an electric current which heat tissue), a cryoprobe (freezing), or a laser. This results in scar tissue later forming around the retinal tear to keep it permanently sealed, so that fluid from the vitreous no longer can pass through and under the retina. A scleral buckle, which is made of silicone, plastic, or sponge, is then sewn to the outer wall of the eye (the sclera). The buckle is like a tight cinch or belt around the eye. This application compresses the eye so that the hole or tear in the retina is pushed against the outer scleral wall of the eye, which has been indented by the buckle. The buckle may be left in place permanently. It usually is not visible because the buckle is located half way around the back of the eye (posteriorly) and is covered by the conjunctiva (the clear outer covering of the eye), which is carefully sewn (sutured) over it. Compressing the eye with the buckle also reduces any possible later pulling (traction) by the vitreous on the retina.

A small slit in the sclera allows the surgeon to drain some of the fluid that has passed through and behind the retina. Removal of this fluid allows the retina to flatten in place against the back wall of the eye. A gas or air bubble may be placed into the vitreous cavity to help keep the hole or tear in proper position against the scleral buckle until the scarring has taken place.

Pneumatic retinopexy

Pneumatic retinopexy is usually performed on an outpatient basis under local anaesthesia. Again, laser or cryotherapy is used to seal the hole or tear. The surgeon then injects a gas bubble directly inside the vitreous cavity of the eye to push the detached retina against the back outer wall of the eye (sclera). The gas bubble initially expands and then disappears over two to six weeks. Proper positioning of the head in the postoperative time period is crucial for success. Although this treatment is inappropriate for the repair of many retinal detachments, it is simpler and much less costly than scleral buckling. If pneumatic retinopexy is unsuccessful, vitrectomy and/or scleral buckling still can be performed.

Vitrectomy

Certain complicated or severe retinal detachments may require a more complicated operation called a vitrectomy. These detachments include those that are caused by the growth of abnormal blood vessels on the retina or in the vitreous, as occurs in advanced diabetes. Vitrectomy also is used with giant retinal tears, vitreous haemorrhage (blood in the vitreous cavity that obscures the surgeon’s view of the retina), extensive tractional retinal detachments (pulling from scar tissue), membranes (extra tissue) on the retina, or severe infections in the eye (endophthalmitis). Vitrectomy surgery is performed in the hospital under general or local anaesthesia. Small openings are made through the sclera to allow positioning of a fibreoptic light, a cutting source (specialized scissors), and delicate forceps. The vitreous gel of the eye is removed and replaced with a gas to refill the eye and reposition the retina. A scleral buckle is often also performed with the vitrectomy. The gas eventually is absorbed and is replaced by the eye’s own natural fluid. In more complicated cases, a silicone oil maybe placed in the vitreous cavity instead of a gas. This oil must be removed at a later date.

Complications of surgery for a retinal detachment:

Discomfort, watering, redness, swelling, and itching of the affected eye are all common and may persist for some time after the operation. These symptoms are usually treated with eyedrops. Blurred vision may last for many months, and new glasses may need to be prescribed, because the scleral buckle changes the shape of the eye. The scleral buckle also can cause double vision (diplopia) by affecting one of the muscles that controls the movements of the eye. Other possible complications are elevated pressure in the eye (glaucoma), bleeding into the vitreous — within the retina — or behind the retina, clouding of the lens of the eye (cataract), or drooping of the eyelid (ptosis). Additionally, infection can occur around the scleral buckle or even more seriously within the eye (endophthalmitis). Occasionally, the buckle may need to be removed.

Results of surgery for a retinal detachment:

The surgical repair of retinal detachments is successful in about 85% of patients with a single vitrectomy or scleral buckle procedure. With additional surgery, over 95% of retinas are reattached successfully. Several months may pass, however, before vision returns to its final level. The final outcome for vision depends on several factors. For example, if the macula was detached, central vision rarely will return to normal due to degenerative changes in the macula. The visual changes in this situation are similar to those seen with the much more common condition known as macular degeneration (age-related macular degeneration or ARMD). Even if the macula was not detached, some vision may still be lost, although most will be regained. New holes, tears, or pulling may develop, leading to new retinal detachments. There may be scarring due to subretinal fibrosis (development of scar tissue beneath the retina). If a gas or air bubble was inserted in the eye during surgery, maintaining proper positioning of the head is also important in determining the final outcome. The use of intraocular gas in phakic eyes (eyes containing the natural lens) is associated with high subsequent incidence of cataract. Close follow-up by an ophthalmologist, therefore, is required and visits will include slit lamp examination and dilated examination of the retina and vitreous. Because of increased risk of retinal detachment in the other eye, dilated examination of the non-operated eye will also be performed. Long-term studies have shown that even after preventive treatment of a retinal hole or tear, 5%-14% of patients may develop new breaks in the retina, which could lead to a retinal detachment. Overall, however, repair of retinal detachments has made great strides in the past 20 years with the restoration of useful vision to many thousands of people.