Retinal Holes and Detachments

Understanding Retinal Holes and Detachments
No one really understands how the retina, the transparent, light-sensitive nervous tissue lining the back wall of the eye, stays in place! There are no strong cellular attachments that can be seen microscopically. Some scientists believe that the retinal pigment epithelium (or RPE), a monolayer of pigmented cells, may produce a biochemical environment that causes the retina to be attracted by a form of static electricity. Others believe that the intraocular fluid pressure pushing against the inner walls of the eye help keep the retina in place. At any rate, it is well known that the retina can come off the back wall of the eye, a condition called a retinal detachment. Because the retina absolutely needs the metabolic support of the underlying layer of cells called the RPE, the retina will not function correctly when detached. The outer layers, the layers normally in contact with the RPE, are comprised of the light-receptive elements (called photoreceptors) and may slowly die after detachment, rendering the retina useless.

Causes of Retinal Detachments
Retinal detachments can occur after severe trauma, such as a strong blow to the head, or after electrocution. They are a particular concern to electrical workers and participants in contact sports. More often, detachments occur insidiously. As a person ages, the retina, like other parts of the body, starts to get thin and weak (atrophic), especially at the periphery (near its attachments with the front of the eye). In addition, the jelly-like ball that fills most of the eye behind the lens, called the vitreous, changes in character from a viscous or firm substance to a loose fluid, a process called syneresis. The vitreous is attached only in the retinal periphery and at the very back of the eye around the optic nerve. When the vitreous becomes fluid, it can move easily and tug on its attachments. It can pull so hard that it can detach and pull a small bit of retina with it. When this occurs, a hole is left in the retina, and vitreous fluid can get into this hole and undermine the retina, ultimately lifting it off. Holes can occur in the aging retina even without vitreous traction initiating them, and these also predispose the retina to detachment. The vitreous can pull the retina off in another way. If the vitreous has blood or abnormal blood vessels in it, this tissue can organize into a scar attached at the retina. As this scar condenses and contracts, it can pull off a large part of the retina. Another way the retina can detach is if some inflammation or growth develops in the layers between the retina and the wall of the eye. This will produce fluid or a mass effect that pushes the retina off.

Symptoms of Retinal Detachment
When a patient suffers a retinal detachment they will not notice pain. Instead they may notice that they do not see well in the affected eye, and may describe the sensation of seeing a "curtain falling". If the detachment affects the area of fine vision, called the macula, the patient will notice a significant loss of vision. If the retinal detachment is secondary to a tear or hole, the patient may notice a sudden increase in floaters, little specks that seem to swim past one eye. These are actually blood cells that escaped from a tiny retinal vessel that was torn as the retina was damaged. The patient may also experience flashing lights. When the photoreceptive elements of the retina are stimulated mechanically, such as by being pulled on, they can initiate signals that are perceived at transient spots of light, visible even when the eyes are closed. If a patient notices a new onset of flashing lights, or new or increased floaters, they should see their retina specialist as soon as possible, to ensure that they do not have an impending retinal detachment.

Therapy for Retinal Holes and Detachments
The retinologist provides a thorough examination of the back of the eye using special lighting and lenses. The ophthalmologist also gently depress the front of the eye so that they can see the very edges of the retina, where it blends into the substance of the inside wall of the front of the eye. This is extremely important, because this is where most of the degeneration and holes start. When the retinologist sees a hole, they will determine whether it places the patient at risk for a detachment. If it does, the retinologist will offer laser therapy. This treatment carefully places tiny burns around the hole, thereby scarring down the surrounding tissue. Now, even if fluid gets into the hole, it cannot undermine the retina. If a retina has already detached, the patient will be offered surgery. Under local anesthesia, the retinologist will remove the fluid from under the retina, and reappose the retina with the eye wall, often by indenting the eyewall with a non-irritating material that wraps around the eye like a belt. This is called a scleral buckling procedure. The retinologist will often remove the vitreous jelly from the eye, because this is frequently involved in pulling or pushing the retina off the eye wall. When a retinal detachment is treated before it affects the very back of the eye (the macula), the prospects for good vision are excellent.