Retinal Detachment

Most retinal detachments are a result of a retinal break, hole, or tear.

A retinal detachment is an eye condition involving the 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. A retinal detachment of this type is known as a rhegmatogenous retinal detachment. Most retinal breaks, holes, or tears are not a result of injury. The majority of retinal breaks, holes, or tears are spontaneous and result when the vitreous gel pulls loose or separates from its attachment to the retina, usually in the peripheral parts of the retina. The vitreous is a clear gel that fills two-thirds of the inside of the eye and occupies the space in front of the retina. As the vitreous gel pulls loose, it will sometimes exert pulling forces, known as traction, on the retina, and if the retina is weak, the retina will tear.

Retinal tears are sometimes accompanied by bleeding if a retinal blood vessel is included in the tear. Everyone develops some shrinkage of the vitreous as they age, and many people develop separation of the vitreous from the retina as they get older. However, only a small percentage of these vitreous separations result in retinal tears.

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 underlying layers in the back of the eye. As more of the liquid vitreous collects behind the retina, the extent of the retinal detachment can increase 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 a retinal detachment in the future.

The retina is an extremely thin tissue that lines the inside of the back of the eye. It is the light-sensitive portion of the eye. When we look around, light from the objects we are looking at enters the eye. The light image is focused onto the retina by both the cornea and the lens. This light striking the retina causes a complex biochemical change within certain layers of the retina and this, in turn, stimulates an electrical response within other layers of the retina. Nerve endings within the retina then transmit these electrical signals to the brain through the optic nerve, which connects the eye to the brain. Within specific areas of the brain, this electrical energy is received and processed to allow us both to see and understand what we are seeing. The retina has been compared to the film of a camera. However, once used, the film has a permanent image on it. The neurosensory retina, in contrast, continually renews itself chemically and electrically, allowing us to see millions of different images every day without them being superimposed.

The retina is about the size of a postage stamp. It consists of a central area called the macula and a much larger peripheral area of the retina. The light receptor cells within the retina are of two types called the cones and the rods. Cones are concentrated within the macular (central) area and provide us with the sharpness of central vision and color vision. Rods predominate in the peripheral area of the retina and allow us to see in conditions of reduced illumination. The peripheral retina allows us to see objects on either side (peripheral vision) and, therefore, provides the vision needed for a person to move about safely. Since this part of the retina contains a lesser concentration of cones, it does not allow for an appreciation of visual detail. Its larger concentration of rods provides better vision during conditions of darkness.

The macula, the smaller central area of the retina containing a high concentration of cones, enables clear central vision to see fine details for such activities as seeing small objects at a distance, reading, or threading a needle. The macula is particularly sensitive to circulatory changes, especially those that occur with aging, such as decreased blood flow. The retina contains a network of branching arteries, which supply blood that carries the needed oxygen and nutrients to the retina, and a network of accompanying veins, which then carry the blood away together with the waste products generated by the retina as it does its seeing work.

Studies have shown that the incidence of retinal detachments caused by tears in the retina is fairly low, affecting approximately one in 10,000 people each year. Many retinal tears do not progress to retinal detachment.

Nevertheless, many risk factors for developing retinal detachments are recognized, including:

• certain diseases of the eyes (discussed below),
• cataract surgery, and
• trauma to the eye.

Retinal detachments can occur at any age but are most common in adults 40 years old and older who are highly nearsighted (myopic) and also in older people who have undergone cataract surgery.

• Lattice degeneration of the retina
  • Lattice degeneration of the retina is a type of thinning of the outside edges of the retina, which occurs in 7%-10% of the general population. The lattice degeneration, so-called because the thinned retina resembles the crisscross pattern of a lattice, often contains small holes.
  • Lattice degeneration is more common in people with nearsightedness (myopia). This tendency to lattice degeneration occurs because myopic eyes are larger than normal eyes and, therefore, the peripheral retina is stretched more thinly.
  • Fortunately, only about 1% of patients with lattice degeneration go on to develop a retinal detachment. All patients with lattice degeneration of the retina should be informed about this condition and cautioned about the importance of seeing an ophthalmologist immediately if they develop sudden floaters, flashes, or a cloud in their vision.
• High myopia
  • High myopia (greater than 5 or 6 diopters of nearsightedness) increases the risk of a retinal detachment. The risk increases to 2.4% as compared to a 0.06% risk for a normal eye at 60 years of age. (Diopters are units of measurement that indicate the power of the lens to focus rays of light.)
  • Cataract surgery or other operations of the eye can further increase this risk in those with high myopia.
• Glaucoma eyedrops
  • People taking certain kinds of eyedrops have an increased risk of developing a retinal detachment. Pilocarpine, which for many years was a mainstay of therapy for glaucoma, has long been associated with retinal detachment. Moreover, by constricting the pupil, pilocarpine makes the diagnostic exam of the peripheral retina more difficult, possibly leading to a delay in the diagnosis.
• Uveitis
  • Individuals with chronic inflammation of the eye (uveitis) are at increased risk of developing retinal detachment.

Cataract surgery, especially, if the operation has complications involving the vitreous, increases the risk of a retinal detachment. Cataracts are a clouding (opacity) within the lens of the eye.

Although cataract surgery does increase the chance of retinal detachment, the risk is low, which is less than 2% over 20 years, and the benefits of cataract surgery ordinarily far outweigh the risk of retinal detachment.

• Blunt trauma, as from a tennis ball or fist, or a penetrating injury by a sharp object to the eye can lead to a retinal detachment.
• A family history of a detached retina that is non-traumatic seems to indicate a genetic (inherited) tendency for developing retinal detachments.
• In a few patients with a non-traumatic retinal detachment of one eye, a detachment subsequently occurs in the other eye. Accordingly, the second eye of a patient with a retinal detachment must be examined thoroughly and followed closely, both by the patient and the ophthalmologist.
• Diabetes that has been complicated by the development of proliferative diabetic retinopathy can lead to a type of retinal detachment that is caused by pulling on the retina (traction) alone, without a tear. Because of abnormal blood vessels and scar tissue on the retinal surface in some people with diabetic proliferative retinopathy, the retina can be lifted off (detached) from the back of the eye. In addition, the blood vessels may bleed into the vitreous gel. This detachment may involve either the peripheral or central area of the retina.
• Non-rhegmatogenous retinal detachments are those that are not a result of a retinal break, hole, or tear. These include conditions known as exudative retinal detachments and tractional retinal detachments.

Flashing lights (photopsia) and floaters (floating spots in the vision) may be the initial symptoms of a retinal detachment or of a retinal tear that precedes the detachment itself. Anyone who is beginning to experience these symptoms should see an eye doctor (ophthalmologist) for a retinal examination. In this exam, drops are used to dilate the patient's pupils to make a more detailed exam easier.

The symptoms of flashing lights and floaters may often be unassociated with a tear or detachment and can merely result from a separation of the vitreous gel from the retina. This condition is called a posterior vitreous detachment (PVD). Although a PVD occurs commonly, in the majority of cases, there are no tears associated with the condition.

The flashing lights are caused by the vitreous gel pulling on the retina or a looseness of the vitreous, which allows the vitreous gel to bump against the retina. The lights are often described as resembling brief lightning streaks in the outside edges (periphery) of the eye.

The floaters are caused by condensation (small solidifications) in the vitreous gel and frequently are described by patients as spots, strands, or little flies. Some people even want to use a flyswatter to eliminate these pesky floaters. There is no safe treatment to make the floaters disappear. Most people with complaints of floaters do not have tears of the retina or a retinal detachment.

If the patient experiences a shadow or curtain that affects any part of the vision of either eye, this can indicate that a retinal tear has progressed to a detached retina. In this situation, one should immediately consult an eye doctor since time can be critical. The goal of the ophthalmologist is to promptly make the diagnosis and treat the retinal tear or detachment before the central macular area of the retina detaches.

Ophthalmologists treat retinal detachments. An ophthalmologist is a medical doctor who chose to specialize in diseases and surgery of the eye. Although all ophthalmologists are trained in the diagnosis of retinal detachment, most surgery for retinal detachment is performed by ophthalmologists who have chosen to sub-specialize in vitreoretinal surgery.

Retinal holes or tears can be treated with laser therapy, known as photocoagulation, or cryotherapy (freezing the retina or cryopexy) to prevent their progression to a retinal detachment. Not all holes require treatment, and many factors determine which holes or tears need treatment. These factors include the type and location of the holes, whether pulling on the retina (traction) or bleeding is involved, and the presence of any of the other risk factors discussed above.

Physicians perform three types of eye surgery for actual retinal detachment:

• Vitrectomy
• Scleral buckling
• Pneumatic retinopexy

Pars plana vitrectomy (PPV or vitrectomy involving removal of the vitreous gel of the eye) is the most common surgery performed for a retinal detachment today. For many years, scleral buckling was the standard treatment for detached retinas. It involves sewing a piece of plastic into the wall of the eye, and physicians still use it in many cases today, sometimes in combination with pars plana vitrectomy.

Both pars plana vitrectomy and scleral buckling are surgeries that doctors perform in a hospital or freestanding surgical center under general or local anesthesia. An overnight stay is sometimes necessary post-operatively. In many cases, intra-ocular gas will be placed into the vitreous at the end of the surgery. This gas pushes against the retina to keep it attached while healing occurs. The gas absorbs over days to weeks, and the patient may be told to position the head in a specific way during this period to maximize the effect of the gas.

Certain complicated or severe retinal detachments may require a more complex operation, including membrane removal and excision of scar tissue. These detachments include those caused by the growth of abnormal blood vessels on the retina or in the vitreous, as occurs in advanced diabetes, and recurrent detachments with membrane formation, known as proliferative vitreoretinopathy (PVR). In these complicated cases, an eye doctor places silicone oil in the vitreous cavity instead of a gas. This oil is permanent and usually requires surgical removal later.

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 critical 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.

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 outcome of 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 outcome. Pars plana vitrectomy and the use of intraocular gas in phakic eyes (eyes containing the natural lens) is associated with a 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 the 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, the repair of retinal detachments has made great strides in the past 20 years with the restoration of useful vision to many thousands of people.

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 eye drops. 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 control 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, the infection can occur around the scleral buckle or even more seriously within the eye (endophthalmitis). Occasionally, the buckle may need to be removed.