At A Glance
- Axial length, genetics, and time spent outdoors can all affect an individual’s risk of myopia progression.
- Methods such as corneal reshaping technology, contact lenses, and atropine can help control myopia progression.
- Young patients and their parents should be educated on myopia control treatments and care.
All eye care professionals are familiar with myopia, and year after year we manage it with spectacle therapy. What if there was instead a way to slow down myopic progression? Well, there is.
For many of us, the bulk of our practice is spent providing glasses to correct myopia. The prevalence of myopia in Europe and the United States is around 35%.1 Some East Asian countries have prevalence rates greater than 80%.1 In a paper studying myopia control trends,2 Holden et al predicted that the prevalence of myopia will reach 50% globally by 2050—that’s roughly 5 billion people. Of that 5 billion, 10% will be highly myopic (-6.00 D or greater). Suffice it to say we have clear data warning us of an epidemic, and in the era of COVID-19 that term should elicit alarm and action.
Patients with moderate (< -3.00 D) and high (< -6.00 D) myopia have increased risk of conditions leading to visual impairment such as glaucoma, retinal detachment, cataract, and myopic maculopathy.3
Several factors contribute to an individual’s risk of developing high myopia. Myopic pathology is particularly linked with the axial length of the eye. In a European study,3 the risk of visual impairment by age 75 increased from 3.8% in patients with axial length of 26 mm or less to 25% in those with axial lengths of 26 mm to 28 mm.
Genetics also play a large role in myopia. Having one myopic parent doubles a child’s risk of myopia.4 If both parents are myopic, the risk more than quintuples. Studies also suggest that less time spent outdoors and, conversely, increased time with near work, increase the risk of myopic progression. This is something that we should be prepared for, especially with increased screen time today with much of the world in quarantine.
RATIONALE FOR MYOPIA CONTROL
The theories posited as rationales for myopia control relate to axial length—the distance from the cornea to the retina—and peripheral hyperopic defocus. Longer axial lengths result in a larger myopic refractive error. The Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) study investigators proposed that myopia results in peripheral hyperopic defocus. It is thought that this signal triggers axial elongation and, hence, myopic progression.5
Another theory suggests that increased accommodative demand results in myopic progression.5 The Figure above visually depicts how standard myopic correction can provide a clear central retinal image but can also create hyperopic defocus in the periphery.
Although the cause of myopic progression is ultimately unclear, three methods can be employed to target the problem: orthokeratology (ortho-K), also called corneal reshaping technology (CRT); contact lens correction; and topical atropine.
In ortho-K or CRT, rigid gas permeable (RGP) lenses are used to temporarily flatten the cornea during overnight wear, resulting in myopic correction throughout the day. CRT is useful in myopia control because, as the central cornea is flattened, the midperipheral cornea is steepened, creating peripheral myopic defocus in the retina. This is thought to down-regulate peripheral hyperopic defocus, the signal for axial elongation.6
The use of CRT lenses has been shown to reduce myopia progression from baseline by 50% over 2 years compared to patients with similar baseline axial lengths in a control group.7 Another study found similar efficacy over 12 years with a safety profile similar to that of standard soft contact lens wear.
CRT is a viable option to provide myopic correction as well as myopia control for patients who don’t want to wear glasses or contact lenses in the daytime. A patient old enough to follow safety precautions for contact lens wear would be an appropriate candidate for this method of myopia control.
SOFT CONTACT LENSES
Soft contact lenses have been a mainstay of myopic correction. Recently, the use of center-distance multifocal designs has been explored as a method for myopia control. Midperipheral rings on these lenses provide a high hyperopic correction that creates peripheral myopic defocus to slow myopia progression (Figure). The center of the lens offers adequate central myopic correction to provide the patient with clear vision.7
Figure. A visual depiction of how standard myopic correction provides a clear central retinal image but can also create hyperopic defocus in the periphery, and how a myopia control soft multifocal contact lens can provide peripheral myopic defocus to slow myopia progression.
Recently CooperVision released its MiSight 1 day soft lens with FDA approval specifically for use in myopia control. Johnson & Johnson also has a soft myopia control contact lens in its testing pipeline.
In studies, multifocal soft contact lenses have achieved much greater control (>70%) over axial elongation than multifocal spectacle therapy.7 Multifocal soft lens wear for myopia control resulted in a 50% reduction of myopia progression over 2 years compared to controls.8
Soft multifocal lenses share the same minimal risk profile as any soft contact lens. The ease of use of soft contact lenses, and the specific FDA approval of at least one lens model for myopia control, makes this option amenable to many patients and their parents.
Atropine is the only medication that has been shown to reduce myopic progression. The exact mechanism is not fully understood, but it may include paralyzing the accommodative system or regulating the muscarinic receptors on scleral and retinal cells that are responsible for axial length growth.9 Atropine has demonstrated up to a 50% reduction in myopia progression.10
The main drawback to atropine is its side effects, which include decreased near vision, increased glare, and light sensitivity due to dilated pupils. However, studies have shown that use of a 0.05% concentration can significantly reduce these side effects while maintaining myopia control effects similar to those of stronger concentrations.11 Formulations of 0.05% atropine must be obtained from a compounding pharmacy, but this can be an effective myopia control method if contact lenses are contraindicated.
As with any other type of service, transparency and education are key for myopia control in your practice. Young patients and their parents should be educated about this type of treatment, even if the patient isn’t myopic. Posters, brochures, and mentions of myopia control by eye care professionals and staff members can help to keep the idea in patients’ minds. The patient’s refractive error at a routine eye exam can be the starting point for a conversation. The CLEERE study identified refractive error at certain ages as the most significant risk factor for future myopia progression (Table).12
The Brian Holden Institute has a great tool on its website (globalmyopiacentre.org/myopia-resources/myopia-calculator/) that can generate a graph predicting an individual’s myopic progression in future years if left untreated. This imagery can be powerful in educating patients and parents. This can be paired with informational packets similar to the one created by the University of Alabama13 as a resource for patients to review at home.
I often introduce the idea of myopia control at an initial visit and provide resources for the patient and family to think about. Then, at a patient-directed return visit or the next annual visit, we begin treatment. Examinations for myopia control should use an axial length measurement tool (such as ultrasound A-scan or optical biometer) as well as cycloplegic refraction to gauge the patient’s true refractive error.
With rates of myopia rising at epidemic levels, optometry should be at the forefront of managing the condition. We have the knowledge and tools at our disposal to educate patients about this necessity and treat it as a standard of care.
- 1. Si JK, Tang K, Bi HS, Guo DD, Guo JG, Wang XR. Orthokeratology for myopia control: a meta-analysis. Optom Vis Sci. 2015;92(3):252-257.
- 2. Holden BA, Fricke TR, Wilson DA, et al. Global prevalence of myopia and high myopia and temporal trends from 2000 through 2050. Ophthalmology. 2016;123(5):1036-1042.
- 3. Tideman JW, Snabel MC, Tedja MS, et al. Association of axial length with risk of uncorrectable visual impairment for Europeans with myopia. JAMA Ophthalmol. 2016;134(12):1355-1363.
- 4. Jones LA, Sinnott LT, Mutti DO, Mitchell GL, Moeschberger ML, Zadnik K. Parental history of myopia, sports and outdoor activities, and future myopia. Invest Ophthalmol Vis Sci. 2007;48:3524-3532.
- 5. Mutti DO, Hayes JR, Mitchell GL, et al. Refractive error, axial length, and relative peripheral refractive error before and after the onset of myopia. Invest Ophthalmol Vis Sci. 2007;48(6):2510-2519.
- 6. VanderVeen DK, Kraker RT, Pineles SL, et al. Use of orthokeratology for the prevention of myopic progression in children: a report by the American Academy of Ophthalmology. Ophthalmology. 2019;126(4):623-636.
- 7. Aller TA, Liu M, Wildsoet CF. Myopia control with bifocal contact lenses: a randomized clinical trial. Optom Vis Sci. 2016;93(4):344-352.
- 8. Walline JJ, Greiner KL, McVey ME, Jones-Jordan LA. Multifocal contact lens myopia control. Optom Vis Sci. 2013;90(11):1207-1214.
- 9. Wu PC, Chuang MN, Choi J, et al. Update in myopia and treatment strategy of atropine use in myopia control. Eye (Lond). 2019;33(1):3-13.
- 10. Chia A, Lu QS, Tan D. Five-year clinical trial on atropine for the treatment of myopia 2: myopia control with atropine 0.01% eyedrops. Ophthalmology. 2016;123(2):391-399.
- 11. Yam JC, Jiang Y, Tang SM, et al. Low-concentration atropine for myopia progression (LAMP) study: a randomized, double-blinded, placebo-controlled trial of 0.05%, 0.025%, and 0.01% atropine eye drops in myopia control. Ophthalmology. 2019;126(1):113-124.
- 12. Zadnik K, Sinnott LT, Cotter SA, et al. Prediction of juvenile-onset myopia. JAMA Ophthalmol. 2015;133(6):683-689.
- 13. Myopia Control Clinic At UAB Eye Care: Information And Consent Form. [pdf] UAB Eye Care. 2020. www.clspectrum.com/resources/myopia_consent_apucker. Accessed August 19, 2020.