Effects of Different Designs of Multifocal Soft Contact Lens on Choroidal Thickness and Peripheral Refraction

Abstract

SIGNIFICANCE: Myopia, as a disease, is now at epidemic proportions worldwide. Low and high myopia increases the risk of serious eye diseases such as retinal detachment, cataracts, and glaucoma. By decreasing myopia progression, the risk of developing serious retinal diseases can be reduced. Inducing myopic defocus in the peripheral retina can slow myopia progression. However, the optimal area, distribution, and magnitude of defocus to result in the best possible myopia retardation is still unknown. Recently, a strong correlation between the change in peripheral refraction and the power profiles of multifocal soft contact lenses (MFSCL) has been observed, proposing an opportunity to understand how defocus manipulation influences choroidal thickness (ChT) and peripheral refraction (PR) across various MFSCL designs and add powers. Consequently, it can contribute to improving the current myopia control optical interventions, specifically MFSCLs, and a better understanding of the short-term ChT changes to myopic defocus, which can eventually enhance the current myopia management success rates. PURPOSE: To investigate the short-term impact of various designs of soft multifocal contact lenses (spherical and aspherical), combined with two magnitudes of myopia control add powers (+3.00 D and +5.00 D), on the choroidal thickness and the retinal defocus profile. METHODS: Twenty-one adult subjects (17 females and 4 males) with a mean age of (25.19 ± 3.6 years) and a mean refractive error of (-0.59 ± 0.7 D) were recruited in a prospective randomized crossover design study. Each subject was fitted binocularly with four center-distance multifocal soft contact lenses in a randomized order. Each MFSCL design varies in the treatment zone design (spherical and aspherical) or the add power (+3.00 and +5.00 D). The four different designs are MFSCL A (spherical, +3.00 D), MFSCL B (spherical, +5.00 D), MFSCL C (aspherical, +3.00 D), and MFSCL D (aspherical, +5.00 D). Each subject wore each assigned MFSCL for 30 minutes while exposed to a distance visual task over four scheduled visits. ChT baseline measurements were taken before the wear of MFSCLs. Post-exposure ChT measurements were obtained with at least a one-day washout period between MFSCL designs. PR baseline and the change of peripheral defocus profile with the wear of MFSCL designs measurements were collected in a separate visit. RESULTS: No significant difference in choroidal thickness was observed following the wear of MFSCL designs A, B, C, and D (p > 0.05). All MFSCL designs have shown a statistically significant myopic shift from baseline for 10o of the nasal field, and 10o, 20o of the temporal field (p < 0.05). A statically significant myopic shift from baseline for 20o of the nasal field, and 30o of the temporal field was observed with the wear of MFSCL deigns B, C, and D (p < 0.05). CONCLUSIONS: 30 minutes of myopic defocus exposure wearing MFSCLs is insufficient to show significant ChT changes. Longer wear time should be investigated. Our results suggest a design and dose-dependent effect with the aspherical design provided a greater peripheral myopic shift than the spherical design, and higher add power (+5.00 D) exhibited greater peripheral myopic shift than (+3.00 D) within the same design. This finding can have a potential implication for enhancing the current optical myopia control designs.