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Multifocal gas permeable contact lens (MFGPCL) designs that incorporate a smaller center zone diameter with a higher add power may limit visual performance, according to findings published in the Journal of Optometry.
Researchers recruited patients with stable myopia, a best-corrected visual acuity of 0.0 logMAR, and a maximum astigmatism of −1.75 D for the randomized, balanced block study (N=17, mean age 23.17±4.48 years, baseline spherical equivalent −3.18±2.59 D). They randomized participants to receive 2 of 4 MFGPCL center distance designs: a 1.5 mm zone with a 3.0 D add (design A), a 1.5 mm zone with a 1.5 D add (design B), a 3.0 mm zone with a 3.0 add (design C), and a 3.0 mm zone with a 1.5 D add (design D). The team instructed participants to wear the lenses for at least 4 hours per day for 1 week followed by a 1-week washout period during which they exclusively wore spectacle lenses. At the conclusion of the washout period the researchers fit participants with a second lens design, which they also wore for a period of 1 week. The team assessed visual acuity and contrast sensitivity at baseline and following 1-week of lens wear.
Researchers determined that none of the 4 MFGPCLs had a statistically significant correlation with distant (F[3,44], 1.5; P =.22) or near visual acuity (F[3,53], 1.5; P =.21).
They did, however, note a statistically significant reduction of the change in the area under the logarithmic contrast sensitivity function (F[3,50], 10.1; P <.001). The investigators found that lens design A was associated with this reduction due to a deterioration of the distance contrast sensitivity for that design (F[3260], 19.7; P <.001).
Participants also reported that design A worsened distance vision and vision while walking (P <.01). However, they tolerated and adapted well to the other 3 designs.
“The results of this study indicated that MFGPCL in various distance zone sizes and add powers, fitted to young myopes, were quickly adapted and well-tolerated without significant visual compromise as observed by visual acuity and contrast sensitivity except with design A (DZ1.5/add3.0),” according to the researchers.
This study was limited by its short duration and small sample size.
Reference
Alanazi M, Caroline P, Lampa M, Liu M. Visual performance with multifocal corneal gas-permeable contact lenses in young adults: A pilot study. J Optom. Published online February 22, 2022. doi:10.1016/j.optom.2022.01.001
