Myopia does not get the attention it deserves, despite its status as the most common ocular problem worldwide, with a prevalence that is expected to increase dramatically in the next 30 years.¹ Ocular morbidity from myopia is expected to significantly impact ophthalmology in general — and vitreoretinal practices in particular. Retinal physicians increasingly will need to address these developments, both in terms of clinical management of disease pathology as well as with respect to patient advocacy to minimize the consequences of myopia.

Here are five need-to-know facts retinal physicians should know about myopia.

1 MYOPIA IS ON THE RISE

Myopia is defined as a condition in which the spherical equivalent objective refractive error is less than or equal to -0.50 diopters (D) in either eye.

Myopia prevalence worldwide was 22% in 2000 and is expected to grow dramatically to 52% by the year 2050.² The future for high myopia — characterized as a spherical equivalent objective refractive error of less than or equal to -5.00 D in either eye — has a significantly higher degree of morbidity and is even more dire.

The condition’s worldwide prevalence was 2.2% in 2000, but is expected to grow 10% by the year 2050.² Retinal physicians need to be aware of the myopic disease burden given the expected increasing prevalence.

2 MYOPIA IS ASSOCIATED WITH RETINAL DETACHMENT AND OTHER CONDITIONS

Myopia is not a benign or stationary condition. Once established, the condition progresses with increasing refractive error. Pathologic myopia occurs when there is posterior segment pathology from axial elongation and is found in 1% of the Caucasian population and 1% to 3% of the Asian population.³ Myopia progression is the primary cause of blindness and low vision in 7% of those of European descent and in 12% to 27% of those ofAsian descent.³

Indeed, myopia is associated with an increased incidence of retinal detachment, glaucoma, and cataracts. Given the increased likelihood of retinal breaks and detachments in myopic eyes, retina specialists need to be proficient in examination of the peripheral retina.

Ophthalmologists need to be cognizant of the sequelae of myopia, and, given the risk of retinal detachment, to be aware of the need for prompt referral of cases of myopia.

3 ENVIRONMENT — NOT GENETICS — IS THE PRIMARY RISK FACTOR FOR MYOPIA

While genetics play a minor role in the pathology of this condition, environmental factors are at the root of the current myopia epidemic.⁴ The projected worldwide increase in myopia and high myopia prevalence is too rapid to be explained by genetics alone. Indeed, the primary risk factors for myopia are time indoors and schooling.⁵

Retina specialists, as well as optometrists, ocularists, and ophthalmologists, need to be aware of myopia risk factors in order to provide their patients with appropriate counseling and disease awareness.

Given the potential disease burden of myopia in the decades ahead, policymakers, too, need to be made aware of the risk factors. Children should be encouraged to spend more time outside and less time in front of screens. Given that schooling is associated with increased myopia, policymakers need to address opportunities to mitigate risk factors that lead to myopic progression during school years. Eyecare professionals are best suited to serve as patient advocates to address these issues.

4 COMPLICATIONS OF MYOPIA CAN BE SEVERE

Myopia-related vision loss can be attributed to multiple pathologic entities. Macular choroidal neovascularization (CNV) is one of the most frequent complications that leads to loss of central vision in patients with pathologic myopia. Myopic CNV develops in 10% of highly myopic patients. Additionally, 30% of myopic patients who have a CNV in one eye eventually develop CNV in the other eye.⁶

While myopic CNV is not intensely active and has a tendency to regress spontaneously, progression from an active exudative phase to macular scarring is common and results in irreversible loss of central vision. Consequently, the prognosis of myopic CNV is poor.

Natural history studies show that at onset of myopic macular CNV, 70% of patients have a visual acuity better than 20/200; however, at 5 and 10 years after onset, visual acuity decreases to 20/200 or less in 89% and 96% of patients, respectively.⁶

The need for early recognition and treatment is imperative. The preferred treatment for myopic macular CNV consists of intravitreal vascular endothelial growth factor (VEGF) inhibitors, with 40% of patients experiencing significant visual improvement of 3 lines or more at 1-year follow-up. Although myopic CNV recurs, typically within 6 months of initial treatment, the number of anti-VEGF injections ranges from 2.4 to 4.9 annually.⁶

5 EFFORTS TO PREVENT MYOPIA PROGRESSION ARE PROMISING

The 2017 American Academy of Ophthalmology (AAO) Myopia Report states, “Level I evidence supports the use of atropine to prevent myopic progression. Although there are reports of myopic rebound after treatment is discontinued, this seems to be minimized by using low doses (especially atropine 0.01%).”⁷

The first clinical trial of atropine for myopia was published in 1979 and involved 1% atropine in the eyes of 62 children.⁸ The results showed treated eyes had reduced or stable myopia. This provided the initial rationale for using atropinization to impede myopic progression.

Atropine, a muscarinic receptor antagonist at the ciliary muscle, prevents accommodation. Although atropine’s mechanism of action is still not fully understood, evidence suggests atropine prevents myopia in human and animal studies.⁹

The debate continues on whether atropine is a viable and safe real-world option. However, both the available evidence and the AAO Myopia Report indicate that treating myopia progression with atropine is promising. Additional studies are needed to better elucidate the mechanism of action and the ideal dosing paradigms to best stymie the myopia epidemic.

KEEP AN EYE ON FUTURE MYOPIA DEVELOPMENTS

In the face of myopia’s growing prevalence, there is, nevertheless, reason to maintain a cautious optimism with respect to treatment aimed at both preventing the condition’s progression as well as addressing its consequences. Retina specialists would do well to keep an eye on the latest research and developments in myopia, for both their benefit and that of their patients. NRP

REFERENCES

1. World Health Organization. The impact of myopia and high myopia. 2015. Available at: https://www.who.int/blindness/causes/MyopiaReportforWeb.pdf ; last accessed Aug. 26, 2019.
2. Ohno-Matsui K, Lai TY, Lai CC, Cheung CMG. Updates of pathologic myopia. Prog Retin Eye Res. 2016;52:156-187.
3. 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.
4. Morgan IG, French AN, Ashby RS. The epidemics of myopia: aetiology and prevention. Prog. Retin. Eye Res. 2018;62:134-149.
5. Dolgin E. The myopia boom. Nature. 2015;519(3):276-278.
6. Ryan’s Retina (6th Edition). Editors: SriniVas Sadda. Elsevier 2017.
7. Pineles, SL, et al. Atropine for the prevention of myopia progression in Children. Ophthalmology. 2017;124(12):1857-1866.
8. Bedrossian, RH. The effect of atropine on myopia. Ophthalmology. 1979; 86(5):713-717.
9. McBrien NA, Stell WK, Carr B. How does atropine exert its anti-myopia effects? Ophthalmic Physiol Opt. 2013;33(3):373-378.