Overview of Retinal Detachment
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 of Retinal Detachment
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 of 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.
- 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.