Myopia is the most common eye disorder in the world; it is estimated that approximately half of the world’s population will be myopic by 2050 (Holden et al, 2016). Myopia is an epidemic worldwide, but Asian countries are more affected. For example, up to 84% of high school students in Taiwan are myopic (Wu et al, 2016).
High myopia is associated with comorbidities such as early onset cataract, glaucoma, retinal detachment, and macular degeneration (Cho et al, 2016). The progression of myopia is typically faster at younger ages; therefore, preventing children from developing high myopia and its associated visual impairments is crucial.
Current Effective Approaches
Myopia management involves either preventing the onset or limiting the progression of myopia. Effective approaches for limiting the progression include antimuscarinic agents, such as low-dose atropine, or contact lens options, such as orthokeratology and soft bifocals (Walline, 2016).
The mechanism of myopia management effect for antimuscarinic agents is unknown; however, it is not a result of reduced accommodation (McBrien et al, 2013). Atropine is a nonspecific muscarinic receptor antagonist that causes cycloplegia and mydriasis. The most effective myopia management agent is 1.0% atropine, but photophobia and near blur side effects have prohibited its wide use (Chia et al, 2012). Lower doses of atropine, such as 0.05%, are more tolerable; they cause fewer side effects and are still effective at retarding both axial length and refractive error progression in children (Yam et al, 2019).
Contact lens myopia management involves providing a myopic blur cue to the retina, which is assumed to act as a retinal cue to slow myopic eye growth (Walline, 2016).
A Possible Combination
The mechanisms of neither contact lenses nor atropine in myopia management are fully understood. Different mechanisms may be involved, and a synergistic effect could exist if contact lenses are combined with low-dose atropine. Long-term studies are underway evaluating low-dose atropine combined with bifocal soft contact lenses (Huang et al, 2019) and with orthokeratology (Tan et al, 2019) in retarding the progression of myopia.
Take for example a 13-year-old Hispanic male with a history of bilateral degenerative myopia. His current cycloplegic refraction was –14.75 –2.00 x 160 and –15.50 –2.00 x 015 in the right and left eyes, respectively, with both eyes corrected to 20/25. His current axial length measurement was 29.14mm in the right eye and 29.17mm in the left eye. For the previous three years, he had been on soft bifocal contact lens therapy for myopia management and had both a stable refraction of –13.50 –2.00 x 160 and –14.50 –2.00 x 015 and an axial length of 28.68mm and 28.72mm in the right and the left eyes, respectively. Due to the significant increase in the patient’s refractive and axial myopia, he was prescribed combined therapy of low-dose atropine 0.05% at nighttime and daytime wear of scleral bifocal contact lenses in both eyes.
High myopia is best prevented. For children who progress on monotherapy of bifocal contact lenses or orthokeratology for myopia management, consider combination therapy with low-dose atropine. CLS
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