Retinitis pigmentosa is the name given to a group of diseases that affect the retina.
The retina, located in the back of the eye, acts like the film in a camera. It is a delicate layer of cells which picks up the picture and transmits it to the brain - where the “seeing” actually occurs.
In retinitis pigmentosa, the retina begins to degenerate, which first causes peripheral (side) vision and night vision to diminish, and then, usually only decades later, the central vision as well.
There are several types of retinitis.
Toxoplasmic retinitis, which may be either acquired or congenital, is caused by a microorganism. If the condition is congenital, the microorganism was passed to the fetus through the placenta. A similar type of retinitis is caused by a blood-borne infection that settles in the eye.
Exudative retinitis stems from unknown causes but may result in detachment of the retina from the internal surface of the eyeball.
Retinitis pigmentosa is an inherited disorder in which excessive amounts of a substance called phytanic acid accumulate and cause extensive damage to the retina.
Often one of the earliest symptoms of retinitis pigmentosa is difficulty seeing at night or in dimly lit places (night blindness). Later there is a very gradual loss of side vision, resulting in “tunnel vision” in some cases.
The symptoms of retinitis pigmentosa generally worsen over a period of years. When other members of a family also are affected, the rate of vision loss is usually similar to that experienced by the other affected members.
The symptoms of retinitis pigmentosa are night blindness, inflammation of the retina, marked limitation of the field of vision (tunnel vision), loss of kinesthetic sense (sense of body movement), shrinkage of the retina, clumping of retinal pigment, and dislodging of the blood vessels of the retina.
Many of the same symptoms are found in other forms of retinitis. They are sometimes accompanied by cloudiness of the vitreous humor (the liquid that fills the cavity behind the lens of the eyeball). This can be detected by a physician examining the interior of the eye with a special lighted instrument called an ophthalmoscope.
In the case of retinitis pigmentosa, there is little that can be done.
If the retina is detached (a condition often caused when a hole in the retina allows fluid to seep into the eye and create a pocket), surgery is usually the treatment. The pocket is eliminated either by freezing or by heat, sometimes with a laser.
If retinitis is the result of a blood-borne infection, that condition must be treated first.
What tests need to be done to diagnose the condition?
Will the visual symptoms progress to total blindness?
What can be expected as it progresses?
Are there any guidelines on what safety measures need to be taken?
What treatment do you recommend?
Are there special eyeglasses that may help?
Will any medication be given? What are the side effects?
Should family members be tested for this condition or should genetic counseling be sought?
A dietary essential, vitamin A, offers some promise in treating retinitis pigmentosa. When 601 patients (18 to 49 years of age) were given high doses of either vitamin A, vitamin E, both, or nearly nothing (trace amounts of the vitamins), scientists found in one study that those patients on vitamin A alone (15,000 international units per day) had on average a 20 percent per year slower rate of decline of remaining vision than those not on this dose. This is a significant finding for a disease in which hope used to be the only treatment.
Instead of the garden-variety of vitamin A, obtained through beta-carotene, the study used the less commonly available vitamin A palmitate. The large quantities required for treatment - three times the RDA and far beyond the 3,500 I.U. that one gets from an average day’s food - means that its use must be under a doctor’s supervision.