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, 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.
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