The Facts About Degenerative Myopia
Have you ever wondered how many people in the United States are nearsighted? The answer may surprise you. In fact, well over 32 million U.S. residents (ages 40 and above) have myopia, or near-sightedness.
According to the National Eye Institute and Prevent Blindness America, 20 million more Americans have myopia than hyperopia, or farsightedness. That makes near-sightedness a common, if somewhat benign, refractive issue.
But most Americans don’t know much about another form of myopia whose effects are serious-even devastating.
Its name is degenerative, or pathological, myopia.
Myopia vs Degenerative Myopia
As just mentioned, myopia is a common eye condition that occurs in nearly one third of the adult population in the U.S. alone. A few simple comparisons are in order:
- Normal eyes: About an inch in diameter and shaped like a sphere, or ball
- Myopic eyes: Longer than normal eyes (length depends on severity of the near-sightedness)
- Pathologically myopic eyes: Noticeably long/oblong (proportionally more like a watermelon versus a cantaloupe)
While myopic eyescan focus well up close, they have difficulty seeing far-away objects. Thisis because the eye’s altered shape hampers the retina’s normal refractive capability. When a patient develops myopia, an eye doctor corrects the error with prescriptive lenses.
By contrast, degenerative myopia causes the eye’s shape to differ from the norm, resulting in severe vision problems. Although degenerative myopia is rare (impacting only two percent of the U.S. population), it’s a leading cause of legal blindness, particularly for those of Middle Eastern or Asian descent.
Likewise, this pathological eye condition is a genetic phenomenon. Thirty percent of cases occur at birth, but degenerative myopia generally begins during adolescence.
Typical Problems Associated with Degenerative Myopia
When a person’s eye elongates, the process stretches and thins the choroid (blood vessels below the retina) and the retina itself. This thinning causes damaging side effects:
Just between the choroid and retina lies a sensitive barrier. When the eye stretches and elongates, it causes tiny ‘lacquer cracks’ in this barrier. In turn, these cracks may lead to further bleeding and the formation of scar tissue.
As the eye stretches, it may create fissures (called macular holes) in the retina’s center, or macula. Photoreceptors in this region of the eye can also die. When that happens, a patient experiences blank spots in his or her field of vision.
If the layer of tissue at the back of your eye called the retina peels away from critical blood vessels, it can starve your retinal cells of oxygen. This occurrence can cause permanent vision loss. If you see light flashes, eye floaters, or unfocused peripheral objects, you should visit an eye doctor as soon as possible. The doctor will check for signs of retinal detachment.
As eyes change shape, internal pressures increase. This increases their vulnerability for other eye diseases like glaucoma-either infantile or adult onset. However, it’s sometimes difficult for doctors to detect glaucoma in patients whose corneas are already rigid.
Such concerns only highlight the critical need for frequent eye exams. In this way, doctors can better monitor even small changes over time.
Secondary Treatments for Degenerative Myopia
Unfortunately, degenerative myopia is a progressive eye disease. Because there is no effective cure, doctors treat patients for secondary eye conditions like glaucoma instead.
For example, doctors can use small injections of Avastin to curtail abnormal blood-vessel growth below the retina. If needed, they can also perform laser welds to forestall retinal detachment.
As to degenerative myopia itself, some promising treatments include:
- Scleral buckling – This experimental ‘reinforcement’ technique allows doctors to connect, or ‘buckle’ the thin sclera in the eye’s posterior with the anterior sclera. Its purpose is to stabilize the eye, thereby slowing the vision loss.
- 7-methylxanthine use – Preliminary research suggests that children with myopia may benefit from this drug, which is used to increase collagen growth while slowing myopic progression.
- Contact lenses – Many doctors find that soft, multi-focal contacts appear to slow myopia in children-possibly by 50 percent or more.
- Intraocular implants – Some severely myopic patients undergo surgeries to implant a ‘bear claw’ lens implant; however, in the case of degenerative myopia, many patients require lens removal (similar to cataract surgery). In this case, surgeons remove the lens but do not insert an artificial lens in its place.
The above treatments are experimental, so only time will tell whether they are effective in the long term.
In the short term, doctors can offer limited treatment options; however, patients can take some proactive measures on their own. For example, every patient should wear protective eyewear, stay away from damaging activities at work or play, and avoid eye rubbing.
Additionally, stay in touch with your retinal specialist so you know about clinical trials and other experimental treatment options. Your specialist can tell you if you’re a good candidate.
Finally, if you or someone close to you has concerns about degenerative/pathological myopia, please contact your retinal specialist as soon as possible. Make frequent and regular eye appointments, and pay attention to the warning signs. It’s worth your time now, and your eye health in the future.