Dr. Jeff Hersh: When the retina begins to detach
Q: My brother had a problem with his retina, but it was not an eye stroke like in your column last week. The eye doctor said his retina had started peeling off. Can you tell me about this?
A: Although the eye is a pretty complex organ, discussing the basics will be enough for today's column. For us to see, light must be focused by a lens at the front of the eye through a clear gel-like fluid (called vitreous humor) so it can land on our movie screen-like retina.
The retina is attached to an underlying support structure that holds it in place, acting like the theater wall that supports a movie screen. If the retina peels away from this support, a patient's vision can be distorted or lost, just as the picture at a movie theater would be distorted or lost if the picture screen peeled away from the wall. This is called retinal detachment.
If only an edge peels away, then that part of the image is lost but, of course, having the edge pulled off its support structure risks the entire retina eventually peeling away.
Retinal detachment is not very common, occurring in 5 to 20 per 100,000 people per year (more common in the elderly). However, over a lifetime there is about a 1 in 300 chance that someone will suffer from this condition.
There are a couple of ways this can happen. Holes can develop in the retina from the vitreous humor contracting and pulling a piece off (the vitreous humor commonly "shrinks" as we age, although it pulls the retina with it only a fraction of the time), trauma to the eye or from other reasons.
Small holes often cause no symptoms or discernable problems. However, if some of the vitreous humor makes it way through the hole to behind the retina it can push the retina away from its support structure and cause the retina to detach, usually occurring over a week or so. A very thin retina, more common at the edges (especially in very near-sighted people), increases the risk of this happening.
Certain inflammatory conditions can cause fluids to build up behind the retina, and this can cause the retina to detach in a similar way as described above.
Last, the retina can be pulled away, for example by the contracting vitreous humor "grabbing" onto the retina at the site of a scar or other location and "pulling" the retina away from its support structure.
It is not surprising that the risks of retinal detachment are trauma (from a blow to the eye or from a surgery, such as cataract surgery), inflammatory disorders, things that thin the retina (severe near sightedness, a family history of retinal detachment), things that pull on the retina (such as scar tissue that forms in severe diabetic eye disease) or a previous history of retinal detachment (either in the same eye or the other eye).
As the retina detaches, the patient's vision will usually change. Early visual symptoms may be flashing lights, floaters, smoky/blurry vision or a curtain-like loss of vision (as the retina peels away).
Floaters are "debris" in the vitreous humor, and having floaters is a normal part of aging. However, the acute onset of lots of floaters (sometimes described as a housefly acutely popping into the vision in one eye) may be indicative of retinal detachment.
Most untreated cases of retinal detachment will lead to vision loss. Thankfully, there are many possible treatments for this condition and more than 90 percent of retinal detachments can be successfully treated, especially if the condition is addressed early.
Treatment for retinal detachment aims at re-anchoring the retina to its supporting structures. This can be done with laser treatments (kind of like welding the retina back in place) or cryopexy (freezing a small area to create a scar to re-anchor it). Injecting air or another gas into the eye (so the bubble can push the retina back into place) is required in some patients.
Sometimes surgery is needed to remove and replace the vitreous humor, and sometimes the surgeon sews a "belt" around the back of the eye to "squish" it, bringing the retina back into contact with the eye's support structure (scleral buckling).
Retinal detachment is a medical emergency. Since prompt treatment can prevent vision loss, anyone developing symptoms of retinal detachment should seek medical care immediately.
Jeff Hersh, Ph.D., M.D., F.A.A.P., F.A.C.P., F.A.A.E.P., can be reached at DrHersh@juno.com.