Be mindful of oblique and ATR astigmatism in high myopes, study advises. Photo: Marc Bloomenstein OD. Click image to enlarge.

Even after full optical correction, some high myopes still have reduced visual acuity. Experts point out that since ocular stretching and pathologic myopia lesions occur even in low to moderate myopes, understanding the factors related to reduced visual acuity is key. To investigate further, researchers recently explored associations between refractive error components (e.g., sphere, cylinder and axis orientation) and reduced visual acuity in low to high myopes with and without pathologic myopia lesions. In their study, they found that both can independently reduce visual acuity, no matter the degree of a patient’s myopia.

Randomly selected eyes of 11,258 myopes were included in the study (mean spherical equivalent: -3.2D, range: -0.5D to -21.51D). A total of 10,528 participants had no pathologic myopia lesions. The researchers defined reduced BCVA as ≥0.18 logMAR.

They reported that 6.4% of myopes had reduced BCVA. The following were significantly associated with reduced visual acuity in the absence of pathologic myopia lesions: high sphere, high cylinder, against-the-rule astigmatism and oblique astigmatism. The researchers also noted that moderate spherical equivalent and high myopic spherical equivalent were associated with reduced visual acuity. Among patients who did have pathologic myopia lesions, the researchers reported that tessellated fundus, chorioretinal atrophy and choroidal neovascularization were significantly associated with reduced visual acuity.

“Nearly 4% of individuals with mild-to-moderate degrees of myopia exhibited reduced visual acuity through full optical correction even in the absence of pathologic myopia,” the researchers wrote in their paper. “Future prospective and experimental studies are needed to understand how retinal mechanisms are associated with reduced visual acuity in myopes even with full optical correction.”

Manoharan MK, Thakur W, Dellhi S, et al. Factors associated with reduced visual acuity in myopes with and without ocular pathologies after optical correction. Ophthalmic Physiol Opt. October 14, 2022. [Epub ahead of print].