High Myopia and Associated Retinal Complications

More than 4 in 10 Americans have myopia, which lets us see things clearly up close but fuzzily at a distance. We fix that problem with glasses or contact lenses and forget about it. But a small percentage of us are born with high myopia, a potentially more serious issue. It can create a new set of difficulties, from retinal detachments to an unusual type of macular degeneration.

Eye doctors define normal vision as 20/20, meaning you see clearly at 20 feet what someone ought to see clearly at that distance. Variations from that standard get measured in diopters; prescriptions for far-sighted people have positive numbers, while those for near-sighted people have negative numbers. A measurement of minus 6 or above indicates high myopia.

High myopia

Who Gets High Myopia?

Like so many health conditions, high myopia runs in the genes, though myopia sometimes skips a generation. Other risk factors include an increase in near work such as screen time and fewer outdoor activities. Children and young adults can develop eyes longer than normal, so images focus in front of the retina instead of on it. Eastern Asians have the highest prevalence of high myopia, though Scandinavian, Hispanic and African-American populations are also at risk.

Doctors can measure myopia in children at any age. A retinoscope projects a beam of light that reflects off the retina, and the degree of reflection indicates the focal length. Myopia that goes uncorrected can lead to amblyopia, , or “lazy eye,” so a doctor will address this deficiency with glasses. A young child with myopia can be at risk for later developing high myopia.

High Myopia and Retinal Detachment

The shape of your eye doesn’t change much after the age of 21, which is why prescriptions usually stabilize after that. However, people with high myopia remain at risk for pathological myopia, excessive growth in the length of the eye. Here’s where retinal problems come in.

The eye contains vitreous gel, a clear substance that gives a space for light to pass through to the retina. Because high myopia changes the shape of the eye dramatically, the retina is thinner and more stretched. Pulling from the vitreous gel tugs on the retina, resulting in higher risk of macular holes, vision distortion, and peripheral breaks.

Most of the time, a retina begins to detach around its edges and can more easily be repaired by a surgeon. While people with high myopia have an increased risk of this type of detachment, they also have an increased risk of detachment that starts in the macula, the part of your retina at the very back of the eye that processes your central vision.

The fovea sits in the center of the macula and contains all our detailed vision, from reading to distance work. In myopic foveoschisis, inner and outer layers of the retina come apart. If the tearing gets worse, fluid may seep under the retina, and the whole retina may come off. Surgeons can fix tears around the periphery of the retina without causing visual distortion but work at its center may create a spot where the patient can’t see.

Preventing Myopic Complications

Doctors need to monitor high myopia frequently. They can surgically peel off that vitreous layer and forestall detachments – it doesn’t grow back -- but they prefer to let patients use their regular vision as long as possible. While the vitreous gel becomes easier to remove the longer you wait, in certain cases the longer you delay the more likely there will be complications.

High-myopic people may also develop myopic macular degeneration. That can be caused by the traction problems described above or tiny retinal stretch marks called lacquer cracks, which develop in the back of the eye. Neovascularization (abnormal blood vessel growth) spreads through these cracks and causes bleeding. Doctors address this problem, as they do age-related macular degeneration, with drug injections or laser procedures.

Early Detection Is a Must

Doctors look for problems via ocular coherence tomography, a mapping tool that checks for retinal thinning or detachments and monitors foveoschisis and neovascularization. They use ultrasounds to find staphyloma, outpouchings of the eye that can tear the retina, and angiography, dye tests inserted through the arm that reveal abnormal leaking blood vessels.

If retinal detachments or myopic macular degeneration go untreated, both can cause permanent blindness or severe loss of vision that cannot be fixed with glasses. That’s why frequent exams should be a top priority for anyone who has high myopia.

To schedule a retinal consultation at Horizon Eye Care, call 704-365-0555 Monday-Thursday, 8 a.m. to 5 p.m., or Friday, 8 a.m. to 3 p.m. The optical department closes on Fridays at 2:30 p.m.