Myopia

Myopia, or nearsightedness, is one of the most common types of refractive errors a person can have. Myopia usually occurs when an eyeball is too long from front to back. As a result of this shape, light doesn’t focus directly on the retina. Instead, it focuses in front of the retina, which makes it harder to see things that are far away. Other possible reasons for myopia can include corneal curvature and lens thickness. In any case, the imperfect shape affects how the light bends when it enters the eye, which in turn determines how well it focuses on the retina.

In most instances, myopia is relatively harmless and can be easily addressed with glasses, contact lenses or refractive surgery. But some cases are more severe. When myopia measures more than 6.00 diopters, it is known as high myopia and it can increase the risk of blinding conditions, such as retinal detachment and glaucoma.1,2,3

In 2000, the total number of people with high myopia was estimated to be 2.7% globally.4 But by 2050, this figure is projected to increase to 9.8% of the global population. 5

What Causes High Myopia?

Indeed, myopia in general, is on the rise.6,7,8 There is some debate regarding why this might be the case, but most theories focus on kids spending more time performing near tasks and/or less time outdoors. 9

High myopia tends to begin in early childhood, and may not stabilize until early adulthood. What causes the eyeball to feature a long axial length in the first place is not known, but myopia does tend to fun in families and is thought to have a genetic link.

How Is High Myopia Diagnosed?

People with high myopia will likely be very aware of their difficulty to see far away objects, but to confirm this an eye doctor will diagnose the condition during a routine eye exam. Part of this exam involves a refraction, which tests visual acuity and measures the refractive error in diopters.  

If you have high myopia, your doctor will very carefully inspect your retina and will want to monitor you regularly to ensure your continued good health. These regular dilated eye exams are essential, since high myopia is associated with an increased lifetime risk of retinal holes, tears, detachments and more.

High Myopia Treatments

As more and more people develop high myopia—particularly children—researchers are eager to find ways to effectively halt its progression. Indeed, many interventions have been attempted, including bifocal glasses, atropine eye drops, and simply encouraging kids to spend more time outdoors. Unfortunately, none of these have, as of yet, proven to be the silver bullet needed to control myopia progression or the complications that often accompany it.

For patients who have high myopia that is stable—meaning it is no longer progressing—surgery may be an option. For example, some surgeons might perform a clear lens extraction or refractive lens exchange, replacing the eye’s natural lens with a plastic intraocular lens (IOL). Patients can also opt to have a phakic IOL, which has the benefit of being a reversible procedure. LASIK and PRK generally are not performed in patients with high myopia. With any surgical procedure, the risk of retinal detachment in patients with high myopia is a significant concern.

When myopia is not stable or if surgery is deemed too risky, glasses or contact lenses can be safely prescribed for vision correction in patients who have high myopia.

Scleral Lenses for High Myopia

If you have high myopia, doctors can usually offer functional vision with eyeglasses or soft contact lenses. However, many doctors opt for a gas permeable (GP) lens design in high myopia patients because these lenses are known to offer outstanding optical quality, which is important when vision is so severely compromised to begin with. Unfortunately, many patients suffer from discomfort with traditional corneal GP lenses, which land on the sensitive corneal tissue

An alternative GP design, called a scleral GP lens, can often overcome this by vaulting over the cornea and landing on the relatively insensitive sclera. A scleral lens is a type of GP lens, featuring a large-diameter that allows the lens to rest on the white part of the eye, known as the sclera. Unlike traditional, small diameter GP lenses that rest on the highly innervated and sensitive cornea, a scleral lens vaults over the cornea and is much more comfortable than its smaller diameter counterpart.  Since the emergence of modern scleral lenses approximately 15 years ago, they have gained increasing utility amongst doctors and patients due to their high level of comfort and visual stability.

If you have high myopia, visit your eye doctor to determine the most appropriate management strategy for you.

 


[1] Rein DB, Zhang P, Wirth KE, Lee PP, Hoerger TJ, McCall N, Klein R, Tielsch JM, Vijan S, Saaddine J: The economic burden of major adult visual disorders in the United States. Arch Ophthalmol 2006;124:1754–1760.

[2] Eye Disease Case-Control Study Group, Risk factors for idiopathic rhegmatogenous retinal detachment. Am J Epidemiol, 1993. 137(7):749-57.

[3] Saw SM, et al. Myopia and associated pathological complications. Ophthalmic Physiol Opt, 2005. 25(5):381-91.

[4] Holden, Brien A. et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology , Volume 123 , Issue 5 , 1036 – 1042.

[5] Holden, Brien A. et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology , Volume 123 , Issue 5 , 1036 – 1042.

[6] Vitale S, Sperduto RD, Ferris FL. 3rd, Increased prevalence of myopia in the United States between 1971-1972 and 1999-2004. Arch Ophthalmol, 2009. 127(12):1632-9.

[7] Bar Dayan Y, et al. The changing prevalence of myopia in young adults: a 13-year series of population-based prevalence surveys. Invest Ophthalmol Vis Sci, 2005. 46(8):2760-5.

[8] Holden, Brien A. et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology , Volume 123 , Issue 5 , 1036 – 1042.

[9] Holden, Brien A. et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology , Volume 123 , Issue 5 , 1036 – 1042.