Is Your Problem a Detached Retina? — Watchtower ONLINE LIBRARY

Is Your Problem a Detached Retina?

THE trouble may appear as sudden flashes of light or as a hazy or wavy curtain floating across your field of vision. Objects seem to lack definition. Perhaps showers of spots impair your eyesight.

Not all these symptoms in themselves indicate serious eye trouble. However, if any of them persist, probably it will be wise to visit your eye doctor. The problem may be a detached retina. What does that mean?

The Marvelous Structure of Your Eyes

A look at the marvelous structure of your eyes will be informative. The eyeball, or “globe,” is round, except at the front, where it has a bulge. “This bulge,” notes the book Living with Your Eye Operation, “contains the light-gathering apparatus of the eye. The ‘skin’ of the entire eyeball is opaque [nontransparent] to light except at this bulge, where it is normally a beautifully clear and round window called the cornea.”

Behind the cornea is the colored iris, with a hole, or pupil, at its center. The iris automatically increases or decreases the size of the pupil to control the amount of light entering the eye.

Just behind the iris is the crystalline lens. This works together with the cornea to focus light at the rear of the eyeball, where it is converted into electrical impulses that are transmitted to the visual center of the brain. It is the brain, not the eyes, that actually does the “seeing.”

Back of the lens the eyeball is filled with vitreous humor. This is a transparent jellylike substance made up mostly of water, with a tiny percentage of solids.

The Eyeball’s Unique “Skin”

The “skin” of the eyeball consists of three layers. The outermost layer is the sclera. It is tough, fibrous and opaque over most of the eye, preventing light from entering. At the front, however, the sclera becomes the transparent cornea.

The middle layer of this skin is highly complicated. At the front of the eyeball it separates into other structures, including the iris. However, over four fifths of the eyeball it forms an essentially continuous layer called the choroid.

It is the third or innermost layer of the eyeball’s three-ply skin that especially captures our attention. This is the retina. The magazine MD of July 1970 explains that the retina is a “paper-thin membrane that gives the light-images entering the eye the shape, color and texture that the brain perceives.” Though “paper thin,” the retina consists of many distinct layers. According to The World Book Encyclopedia, “it, consists of three main layers of cells: (1) nerve cells toward the central cavity, (2) light-sensitive cells in the middle, and (3) pigment-containing cells toward the outside near the choroid.”

The light-sensitive cells in the retina number many millions. The article in MD points out: “Each eye contains some 130 million rods that respond to dim light and transmit only shades of gray; the 7 million cones, concentrated largely at the center of the retina in the fovea, react to bright light and are responsible for color vision.” Incidentally, the fovea is only about one square millimeter in area, about this size: ^▫.

Tiny nerve fibers extend from the rods and cones in all parts of the eye. These come together at the rear of the eyeball to make up the optic nerve, which connects with the brain. Concerning the retina, a Nobel Prize-winning eye specialist, Santiago Ramón y Cajal, observed in his Recollections of My Life:

“The retina always fascinated me because I believed that life never succeeded in constructing a machine so subtly devised and so perfectly adapted to an end. . . . My study of this membrane for the first time weakened my faith in Darwin’s hypothesis of natural selection, for I was amazed and confounded by the supreme constructive ingenuity revealed not only in the retina and in the dioptric apparatus of the vertebrates but even in the meanest insect eye. . . .”

A Threat to Good Vision

Good vision requires a healthy retina. But frequently something threatens its health. How so? The retina becomes detached from the choroid layer that lies behind it and nourishes it. This leads to degeneration of the retina and likely to blindness.

Tens of thousands of persons suffer from this malady. According to the Medical Tribune of April 25, 1973, “the incidence of retinal detachment is estimated at about 15,000 to 20,000 a year, and of these, only about 15 to 16 per cent are trauma-related; the rest are spontaneous.”

Retinal detachment occurs more frequently among people over the age of fifty. One out of every four sufferers has the problem in both eyes. Persons with diabetes are twenty times as likely to become blind from retinal disease as are nondiabetics.

How the Retina Becomes Detached

What causes the retina to become detached from the nourishing choroid layer behind it? While blood vessels in the choroid nourish the retina, they do not connect with it. There is very little adhesive between the two layers. The book Living with Your Eye Operation explains: “In effect, the retina lies against the choroid like some silky wall covering that is not pasted to the plaster, but is pushed against the wall by the wind.” In healthy eyes the vitreous humor presses the retina snugly against the choroid. But if blood or any other substance gets behind the retina, between it and the choroid, this acts to detach the retina from its source of nourishment.

Usually the problem begins with a tear, break, hole or some other damage to the retina. This permits fluid to seep behind the retina, floating it off the choroid. The reasons for the initial damage to the retina may be “traumatic,” such as bumping one’s head. But evidently there must be some prior weakness that makes the retina susceptible to tearing when subjected to trauma.

Why are older people more likely to be afflicted with detached retinas? “After the age of 40,” notes Medical Tribune, “the vitreous body, a collagen gel, shrinks and draws away from the inner surface of the retina; the constant pull of the gel on the retina may eventually tear it in some people, and free water leaks behind the retina, floating it off the choroid.”

Why are diabetics so much more susceptible to retinal detachment? Because diabetes often results in retinal bleeding. As noted above, blood or any other fluid that leaks behind the retina can cause it to become detached.

Try to Preserve Your Vision

Do you enjoy good eyesight at present? It makes sense to do all that you can to preserve it. One thing to avoid is long exposure to bright light, such as often happens during days at the seashore. Experiments with animals have shown that prolonged exposure to bright light causes permanent eye damage. In fact, it may be as dangerous to the retina as staring at an eclipse of the sun.

The publication Optical Developments (February-March 1957) mentions an important factor in maintaining good eyesight: “Proper nutrition is of major importance in the process of vision. It is evident that the full quota of vitamins, minerals and amino acids is to be featured as essential factors in the prevention of visual defects at all stages of life, and in the correction of various dysfunctions if they have not passed the reversible stages.”

Scientists have shown, for example, that the retina contains huge amounts of vitamin A. The pigment “visual purple,” found in the light-sensitive rods and which aids the eyes to adjust to dusk or dim light consists of protein and a substance chemically related to vitamin A. The B vitamins, as well as vitamins C and D, are also essential to healthy eyes. A balanced, nutritious diet ordinarily provides these essential elements.

If you are over forty, there is something else that may help. Since eye problems are more frequent in this age group, a visit to the eye doctor, at least every two years, is recommended. Your doctor’s knowledge and skill may even prevent retinal detachment. How so?

By use of an ophthalmoscope and other instruments the doctor can examine the back of your eyeball. He literally “lights up” the inside of your eyeball and looks into it through the pupil and lens. These instruments can reveal both retinal detachment and tears or breaks in the retina that may precede detachment. Prompt treatment may prevent serious complications. But what if the retina has come loose? What procedure might a doctor use to treat this problem? How bright would be your prospects for regaining functional eyesight?

Treatments Highly Successful

If the retina has separated from the choroid, the desired goal is to get it reattached. How can this be done? Bernard Seeman explains in Your Sight—Folklore, Fact and Common Sense: “In 1919 a Swiss physician, Jules Gonin, suggested that retinal detachment could be corrected by cauterizing the tear in the retina, thus causing an adhesive scar that would once more fix the retina to the choroid. . . . Today Gonin’s basic thesis is still applied, but techniques have improved considerably.”

Now the adhesive scar is often made by means of surgical diathermy. This involves a needle bearing high-frequency electric current. Touching it to points on the sclera produces pinpoints of irritation that cause formation of scar tissues. The scar tissues grasp the retina from behind and hold it firmly against the choroid.

More recently the same effect has been achieved by use of light. In the 1950’s a procedure was developed to “spotweld” detached retinas by means of an intense beam of brilliant light from a xenon arc. During the following decade further progress was made by using a laser beam.

Another method of treating detached retinas involves the cryoprobe. This is a tiny probe attached to a freezing unit. In this case frigid temperature, rather than heat or light, produces the adhesive scar. “Cryosurgery, one of the latest developments in the treatment of retinal detachment,” notes Bernard Seeman, “has several advantages over other forms of surgery, particularly in that it is less likely to cause damage to the vitreous than electric diathermy or the ultra-intense light known as laser beam.”

At times large tears in the retina fold back and the flaps become stuck from behind. What can be done about that? Surgical tables have been used that turn the patient upside down so that the force of gravity causes the flap to fall free. In stubborn cases, a needle with a tiny balloon at its tip is inserted into the eye. This is positioned in the fold and inflated, thus gently breaking the adhesions that may have formed. Then the doctor employs usual methods to reattach the retina.

One innovative treatment for retinal detachment has gained much popularity in recent years. This is known as scleral buckling. It involves cutting a thin channel in the sclera at the spot where the retina has become detached. Then the doctor fastens a small silicone rubber tube in the channel. This buckles the sclera inward, pushing it and the choroid against the retina. Concerning this treatment Medical Tribune states:

“Scleral buckling diminishes the pull of the vitreous membranes on the retina by depressing, or buckling, the sclera, thus reducing the size of the vitreous cavity. Then, using diathermy, cryosurgery, or photocoagulation, a scar is produced that closes the retinal breaks, thus permitting reattachment of the retina.”

As to the effectiveness of procedures for correcting detached retinas, Dr. Charles L. Schepens, president of the Retina Foundation of Boston, points out: “Reparative surgery after detachment is about 85 per cent successful, but between 10 and 20 percent of these patients must undergo more than one operation.” Dr. Schepens then adds a sobering note: “If the retina has been completely detached for two years or more, the chances for functional success are nil.”

Is your problem a detached retina? It makes sense to find out; and the sooner you seek help, the better.

[Diagram on page 17]

(For fully formatted text, see publication)

Eye with normal retina

IRIS

CORNEA

LENS

VITREOUS HUMOR

SCLERA

CHOROID

RETINA

OPTIC NERVE

[Diagram on page 18]