Detached Retina

Detached retina is a serious eye condition that almost always leads to blindness if not treated promptly.

The retina is the light-sensitive tissue that lies smoothly against the inside back wall of the eye. Underneath the retina is the choroid, a thin layer of blood vessels that supplies oxygen and nutrients to the retina. Retinal detachment occurs when the retina separates from this underlying layer of blood vessels. Unless it is surgically reattached, permanent vision loss can result.

At the root of this eye disorder are changes to the jelley-like vitreous that fills the vitreous cavity of the eye. Over time, the vitreous may change in consistency and partially liquefy or, it may begin to shrink. Partial liquefaction may progress to a point where the vitreous sags and separates from the surface of the retina. This is called posterior vitreous detachment (PVD) or vitreous collapse.

This is a common condition and occurs to some extent in the eyes of most people as they age, but usually it does not cause serious problems. The shifting or sagging vitreous may cause the appearance of new or different floaters in the field of vision. What looks like spots, flecks, hairs, or strings are actually small clumps of gel, fibers, and cells floating in the vitreous. What is seen are the shadows that this material casts on the retina. Common floaters appear gradually over time and, while annoying, are rarely a problem and do not require treatment.

If the vitreous pulls on the retina as it shifts and sags, flashes of light (photopsia) may be seen when the eyes are closed or when in a darkened room. The phenomenon lasts only a few seconds. However, floaters and flashes can signal a more serious eye problem, particularly if they appear suddenly and with great intensity.

When the pull of a sagging vitreous is strong enough, the retina may tear, leaving what looks like a small, jagged flap in the retina. Most tears occur along the periphery of the retina. That is where the vitreous is more firmly attached and cannot separate without tugging hard. Such tears can lead to retinal detachment, which occurs when the vitreous fluid starts to leak under the retina in places opened by the tears.

Leakage can also occur at tiny holes where the retina has thinned because of ageing or other retinal disorders. As liquid collects, the areas of the retina surrounding these defects may begin to peel away from the underlying layer, the choroid. Over time, these detached areas may expand and, like wallpaper, once torn, they slowly peel off the wall. The areas where the retina is detached lose their ability to see.

Not all tears and holes in the retina lead to retinal detachment. Sometimes the retina remains attached to the choroid rather well despite these minor defects. However, detachment that goes undetected and untreated can progress and eventually involve the entire retina with complete loss of vision. The condition is usually painless, but visual symptoms almost always appear before it occurs. Some warning signs include the following:

• the sudden appearance of many floaters;
• a sensation of flashing lights that usually occurs in one eye but can be in both eyes at the same time;
• a shadow over a portion of the visual field;
• blurred vision. Since most tears occur along the periphery of the retina, blurring may be noticeable initially in the peripheral vision field.

When the retina tears, small blood vessels may be broken, allowing blood to seep into the vitreous and cause hazy vision or specks that appear to float before your eyes. If the floaters appear suddenly as a cloud of spots or a spider web and are accompanied by flashes of light, an ophthalmologist should be seen immediately as this may be the beginning of a retinal detachment. The risk of retinal detachment increases in white males, especially those who are nearsighted. Other risk factors include previous eye surgery or eye injury, as well as weak areas in the periphery of the retina.

An eye doctor can determine if there is a retinal hole, tear, or detachment by looking carefully at the retina with an ophthalmoscope. If blood in the vitreous cavity prevents a clear view of the retina, the doctor my use sound waves (ultrasonography) to obtain a precise picture.

Surgery is the only effective therapy for a retinal tear, hole, or detachment. If such cases are treated before a detachment develops, or if a retinal detachment is treated before the macula detaches, most of the vision can be saved. If a tear or hole has not progressed to a detachment, one of two outpatient procedures may be done: photocoagulation or cryopexy. In most cases, both methods can prevent the development of a retinal detachment.

Photocoagulation involves the surgeon using a laser beam directed through a special contact lens to make burns around the retinal tear. The burns cause scarring, which holds the retina to the underlying tissue. This procedure requires no surgical incision and causes less irritation to the eye than the other procedure – cryopexy.

Cryopexy involves the use of intense cold to freeze the retina around the retinal tear. After a local anesthetic numbs the eye, a freezing probe is applied to the outer surface of the eye directly over the defect. This freezing produces an inflammation that leads to scarring which seals the hole and holds the retina to underlying tissue. Cryopexy is used in instances where the tears are more difficult to reach with a laser, generally along the retinal periphery. The eye may be red and swollen for some time after the procedure.

For a retinal detachment, three different surgical procedures are commonly used: pneumatic retinopexy, scleral buckling, and vitrectomy. Some of these procedures are done along with cryopexy. Their purpose is to close any retinal holes or tears and to reduce the tug on the retina from a shrinking vitreous. The severity and complexity of the condition of the retina will determine which procedure is used.

Pneumatic retinopexy is a surgical technique used for an uncomplicated detachment when the tear is located in the upper half of the retina. It is done on an outpatient basis. First, the surgeon will perform cryopexy around the retinal tear. Then, a small amount of fluid is withdrawn from the anterior chamber to soften the eye. A bubble of expandable gas is injected into the vitreous cavity. Over the next several days, the gas bubble expands, sealing the retinal tear by pushing against it and the detached area that surrounds the tear. With no new fluid passing through the retinal tear, fluid that had previously collected under the retina is absorbed, and the retina is able to reattach itself to the back wall of the eye.

Following surgery, the head must be held in a cocked position for a few days to make sure the gas bubble seals the tear. It takes two to six weeks for the bubble to disappear. Until it does, sleeping on the back is to be avoided. This will keep the bubble away from the lens and reduce the risk of cataract formation or a sudden pressure increase in the eye. Also during this time, no air travel is permitted because a sudden drop in pressure could cause the gas bubble to expand rapidly resulting in dangerously high pressure in the eye.

The success rate of pneumatic retinopexy is not as good as that of scleral buckling, but it can avoid the need for incisional surgery. There are complications that may happen, including recurring retinal detachment, excessive scar tissue formation in the vitreous and retina, cataracts, glaucoma, gas getting under the retina, and infection. A recurring retinal detachment can usually be repaired with scleral buckling or vitrectomy.

Scleral buckling is the most common surgery for repairing retinal detachment and is usually performed in an operating room under local or general anesthesia. However, if the detachment is uncomplicated, it can be done on an outpatient basis. First, the surgeon will open the conjunctiva and treat the retinal tears or holes with cryopexy.

The sclera is then indented (buckled) over the affected area by pressing in with a piece of silicone material, which is either in the form of a soft sponge or a solid piece. The buckle closes the tear and helps reduce the circumference of the eyeball. This prevents further vitreous pulling and separation. If there are several tears or holes or an extensive detachment, the surgeon may create an encircling scleral buckle around the entire circumference of the eye.

The scleral buckle is stitched to the outer surface of the sclera. Before tying the sutures holding the buckle in place, the surgeon may make a small cut in the sclera and drain any fluid that has collected under the detached retina. The buckle is then covered with the conjuctiva. When the incision has healed, there is little evidence of the operation, and the buckle remains in place for the rest of the patient’s life. Some surgeons may choose a temporary buckle for simple retinal detachments, using a small rubber balloon that is inflated and later removed.

Repairing retinal detachment with scleral buckling works more than 80% of the time with one operation, but a reattached retina does not guarantee normal vision. How well the vision is after surgery will depend on whether the macula was affected by the detachement and, if so, for how long. Even if the macula were not affected and scleral buckling successfully repairs the retina, there is still a 10% likelihood of losing some vision because of wrinkling or puckering of the macula.

Scleral buckling is generally successful, but, in about five to ten percent of the cases, the retina fails to reattach to the choroid. This is often caused by the formation of scar tissue on the retinal surface. Any scar tissue before, or after the surgery, will pull on the retina and prevent the reattachment of the retina during new surgery. This can happen one to two months following surgery.

The condition is treated by removing the scar tissue with a procedure called vitrectomy and redoing the scleral buckling. In some complicated cases, the surgeon injects air, other gases, or silicone oil into the vitreous cavity to push the retina back against the wall of the eye. Eventually, the eye absorbs the substance and replaces it with fluid that the eye normally produces. However, silicone oil will not absorb and has to be removed once the retina is reattached and completely healed.

Complications do occur once in a while and can cause the loss of some or all of the vision in the affected eye. Some of these complications are as follows:

• bleeding under the retina or into the vitreous cavity. This can occur while subretinal fluid is being drained or when a buckle suture inadvertently perforates the sclera and enters the eye
• increased pressure inside the eyeball (glaucoma). This is because of a swelling of the choroid and narrowing of the angle in the anterior chamber.
• double vision (diplopia) caused by interference from the buckle with the function of muscles that keep the eyes aligned. It may be temporary but if not, it may require corrective lenses or surgery on the eye muscles.
• failure to accomplish intent;
• retinal detachments that require additional surgery or may be inoperable;
• vitreous hemorrhage;
• change in eyeglass prescription;
• infection;
• poor healing or nonhealing ;
• corneal defects and/or corneal clouding and scarring;
• cataracts, which might require eventual or immediate removal of the lens;
• eyelid drooping;
• loss of circulation to vital tissues in the eye resulting in a decrease or loss of vision;
• permanent blindness;
• loss of the eye;
• phthisis (disfigurement and shrinkage of the eyeball).