Long-term results of perifocal defocus spectacle lens correction in children with progressive myopia

Abstract

Peripheral defocus plays a significant role in the formation of refraction. Perifocal spectacles allow differentiating correction of central and peripheral refraction of the eye along the horizontal meridian and can correct or reduce peripheral hyperopia. PURPOSE: To study the long-term results of wearing perifocal spectacles on the refraction in children with progressive myopia. MATERIAL AND METHODS: Perifocal spectacles were assigned to children of 7-14 years old with progressive myopia from -1.0 to -6.0 D in terms of refractive spherical equivalent. The children were examined before the prescription of perifocal spectacles and after 6 months, 12-18 months, 2 years, 3 years and 4-5 years. We measured visual acuity, the character of vision, refractive error before and after cycloplegia, performed biomicroscopy, ophthalmoscopy and biometry. Peripheral refraction was studied at 15 degrees and 30 degrees points in the nasal (N15 and N30) and temporal (T15 and T30) meridians without correction and while wearing perifocal spectacles. RESULTS: In perifocal spectacles, in the 15 degrees zone, 100% of the eyes formed myopic defocus, which averaged -0.05+/-0.1 D in T15 degrees , -0.25+/-0.16 D in N15 degrees and -0.44+/-0.03 D in T30 degrees . In the N30 degrees zone, the hypermetropic defocus decreased by 4 times and amounted to 0.38+/-0.03 D. The rate of progression of myopia decreased from 0.8 D of baseline values to 0.17 D at 4-5 years of follow-up. After 6 months of wearing perifocal spectacles, the refraction gain was -0.2+/-0.02 D (in the control group it was -0.38+/-0.04 D), after 12-18 months - (-)0.38+/-0.04 D (-0.63+/-0.09 D in the control group), after 2 years - (-)0,78+/-0,06 D (-1.18+/-0,15 D in the control group), after 3 years - (-)0.99+/-0.12 D (-1.65+/-0.20D in the control group). During the 4-5 years of the follow-up, the refractive error in the main group was -1.16+/-0.2 D, which is 60% less than in the control group (-1.95+/-0.2 D). CONCLUSION: Constant wearing of perifocal spectacles reduces the rate of myopia progression in children by 4.5 times compared with the initial rate, and by 1.6 times (by 60%) in comparison with the control group. Perifocal spectacles are recommended as optical means to slow the progression of myopia.