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Overview

Retinal detachment is the separation of the retina from the choroid, a membrane dense with blood vessels that is located between the retina and the sclera ("white" of the eye). The retina is a thin layer of light sensitive tissue that lines the back portion of the eye. When the retina detaches, it is deprived of its blood supply and source of nourishment and loses its ability to function. This can impair vision to the point of blindness.

Incidence and Prevalence
Retinal detachment is relatively rare and occurs in about one in 15,000 (0.3%) of the U.S. population. It is most common in people middle-aged and older. About 6% of the population has retinal holes, but most of these do not lead to retinal detachment.

Patients who are severely myopic (usually greater than 10 diopters) have a 5% risk for developing a detachment and patients who undergo cataract surgery have a 1% risk. The most common predisposing factor is myopia, accounting for 40% to 50% of detachments. About 33% have undergone cataract removal and 10–20% have experienced eye trauma.

Types
There are three types of retinal detachment: rhegmatogenous retinal detachment, tractional retinal detachment, and exudative retinal detachment.

Rhegmatogenous retinal detachment is the most common type and occurs as a result of one or more small tears or holes in the retina. Fluid passes through the hole and flows between the retina and the choroid of the eye. This can cause the retina to separate from the choroid, resulting in detachment.

Retinal tears can be caused by a number of factors; the most common is posterior vitreous detachment (PVD). The vitreous body is a large spherical chamber located between the lens and the retina. Vitreous is the clear, gel-like substance that fills the chamber. In a child’s eyes, the vitreous has a consistency similar to egg white and is firmly attached to the retina. As a person grows older, the vitreous may become thinner and more liquefied, shrinking away from the retina until it separates from it entirely. Vitreous separation occurs in about one-half of all persons by age 50.

PVD is generally harmless and does not affect vision. However, as the vitreous shrinks it can pull on and tear the retina. Once a hole is formed, vitreous can seep through the tear, leading to retinal detachment.

Patients who are nearsighted (myopic) are at risk for rhegmatogenous retinal detachment. The eyes of myopic patients are longer from front to back, and the retina is thinner and more fragile.

Inflammation or injury may cause vitreous shrinkage, resulting in a tear. Eye surgery patients are also at risk, especially those who have undergone cataract removal. Cataract surgery is the most common surgical procedure performed on the eye and is the most prevalent surgical risk factor for retinal detachment. Approximately 20–40% of rhegmatogenous retinal detachments occur in patients who have had cataract removal.

Tractional retinal detachment occurs when adhesions or scar tissue create enough traction on the retina to tear and detach it. The most common causes of tractional retinal detachment are:

• diabetic retinopathy,
• eye disorders caused by sickle cell disease,
• occlusions of retinal blood vessels,
• penetrating eye injury,
• retinopathy of prematurity.

Fluid buildup underneath the retina causes exudative detachment. A disturbance in the blood–retina barrier results in the leakage of fluid into the "space" between the retina and the choroid. Conditions that can lead to this leakage include the following:

• Congenital anomalies, including Coat’s disease (disorder of retinal blood vessels) and nanophthalmos (extremely small eyes)
• Eye tumors, such as choroidal melanoma (malignancy of the choroid)
• Inflammatory conditions including posterior scleritis (inflammation of the sclera) and Vogt-Koyanagi-Harada syndrome (rare, severe inflammation of the iris, ciliary body, and choroid)

Treatment for exudative detachment depends on the underlying cause. If the cause can be controlled, the prognosis is usually very good.

Risk Factors

There are a number of risk factors for retinal detachment. These include:

• Cataract surgery
• Diabetic retinopathy and retinopathy of prematurity
• Family history
• Myopia (nearsightedness)
• PVD complicated by small tears (usually in patients over 50)
• Retinal detachment in one eye increases risk for the other eye
• Thinning of the retina
• Traumatic injury to the eye

Symptoms

Initial symptoms of PVD are called flashes and floaters. As the vitreous shrinks and condenses, it may "tug" on the retina. When this happens, people often see a split-second flash of light, usually in their peripheral vision.

As the vitreous shrinks away from the retina, small fragments of the retina may break off. The vitreous also condenses and may form opaque spots. The fragments and opacities (floaters) appear as small circles, specks, or fine threads in the vision field.

In most people with PVD, floaters become less noticeable as the vitreous continues to detach from the retina. They generally settle to the bottom of the eye, moving out of the field of vision. There is no treatment for floaters and it may take several months for them to become less bothersome or disappear completely. Surgical removal of floaters is controversial because the risk outweighs any benefit.

The sudden appearance of spots or flashes can indicate a tear in the retina. A sudden increase in the number and size of floaters may also be a warning that the retina is tearing. This is sometimes referred to as a "shower of floaters."

Wavy or watery vision may also be a sign that the retina is detaching. Sometimes people notice a dark shadow or the appearance of a "curtain" being pulled over their field of vision. This generally is experienced in the peripheral (side) vision, which is where retinal detachment often begins. Blurred central vision indicates that retinal detachment is progressing and the result is significant, permanent vision loss unless it is repaired.

Retinal detachment usually develops gradually, causing noticeable symptoms, but in some cases it occurs suddenly. This causes total vision loss in the affected eye. Total vision loss can also be caused by a retinal tear that bleeds into the vitreous.

Diagnosis

The earlier the diagnosis is made, the greater the chance to restore vision. Diagnosis is based on symptoms and a thorough examination of the retina.

An ophthalmoscope is used to examine the retina. This is a small hand-held instrument consisting of a battery-powered light and a series of lenses that is held up to the eye. The doctor is able to see the retina and check for abnormalities by shining the light into the eye and looking through the lens. Eye drops are placed in the eyes to dilate the pupils and provide better visualization. When this is done, an indirect ophthalmoscope is used. This instrument is worn on the specialist's head and a lens is held in front of the patient's eye. It allows a greater, wider view of the retina.

Examination with a slit lamp microscope may also be done. This microscope enables the doctor to examine the different parts of the eye under magnification. After instilling drops to dilate the pupil, the slit lamp is used to detect retinal tears and detachment.

A visual acuity test may also be indicated to assess vision loss. This test involves reading letters from a standard eye chart.

Treatment

Surgical treatment for retinal detachment depends on type, severity, and location of the detachment. Risks include infection, bleeding, cataract development, and increased pressure inside the eye. However, without intervention, retinal detachment usually causes permanent partial vision loss or blindness.

The retina can be repaired in about 90% of cases. Approximately 33% of patients with a successfully reattached retina have excellent vision within 6 months of surgery. Others achieve various degrees of vision. The success of surgery depends on the size and location of the damage, the length of time between the onset of detachment and the attempt to repair it, and other complicating factors. Surgery is less effective if the retina has been detached for a long time, if the detachment is severe, or if fibrous tissue has grown on the retina’s surface. In a small number of cases, the retina cannot be reattached because of continuous vitreous shrinkage or fibrous growths on the retina.

Laser Photocoagulation
If the retina is torn or the detachment is very slight, a laser can be used to burn the edges of the tear and halt progression. The fine beam of light produces scar tissue that seals (coagulates) the tear and prevents fluid from passing through. If there is a very small detachment, the laser can seal the retina against the choroid. Laser surgery is usually performed as an outpatient procedure, under local anesthesia.

Cryopexy
Cryopexy uses nitrous oxide to freeze the tissue behind the retinal tear, stimulating scar tissue formation that will seal the edges of the tear. It is usually done as an outpatient procedure, under local anesthesia.

Pneumatic Retinopexy
Pneumatic retinopexy is most effective for detachments that occur in the upper portion of the eye. The eye is numbed with local anesthesia and a small gas bubble is injected into the vitreous body. The bubble rises and presses against the retina, pushing it against the choroid. The gas bubble is slowly absorbed over the next 1 or 2 weeks. Cryopexy or laser is used to seal the retina into place.

Scleral Buckle
Scleral buckle treatment is the most common treatment for retinal detachment in adults. It is more invasive than pneumatic retinopexy and the success of the treatment depends on the size and location of the detachment. In this procedure, a tiny sponge or silicon band is attached to the tough outer membrane of the eye (sclera) to press against the retina and hold it in place.

The buckle is not visible and remains permanently attached to the eye, except in the case of an infant when it must be replaced because of eye growth. Because the scleral buckle elongates the eye, the patient may experience myopia. Existing nearsightedness may worsen and existing farsightedness may improve somewhat. Cryopexy or laser photocoagulation is usually performed during scleral buckle surgery.

Vitrectomy
A vitrectomy may be performed if there is a large retinal tear, a retinal detachment involving the macula, or a nonabsorbing vitreous hemorrhage that is interfering with testing or treatment. In a vitrectomy, the vitreous is removed and replaced with air or a saline solution, which exerts pressure that pushes the retina against the wall of the eye. This procedure is usually performed under local anesthesia in an outpatient setting.

In rare cases, silicone oil is used. However, the oil must be removed once the retina is reattached because the oil interferes with vision. A second procedure is needed to replace the oil with air or another fluid.

Prevention

Preventing retinal detachment is possible by having regular eye exams and seeing an eye care practitioner immediately when early symptoms (floaters and flashes) are experienced. In most cases, small tears can be repaired easily and vision can be preserved. People at high risk should discuss the frequency of eye exams with their practitioner.

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