SIGNIFICANCE With multifocal contact lenses (MFCLs) used for myopia control, questions remain regarding visual performance. Information from nonpresbyopic patients provides insight into how MFCLs affect visual acuity and reading performance. PURPOSE The purpose of this study was to examine the visual performance of center-distance MFCLs in nonpresbyopic adults under different illumination and contrast conditions compared with a single-vision contact lens (SVCL). METHODS Twenty-five adult subjects were fit with three different lenses (CooperVision Biofinity D MFCL +2.50 add, Visioneering Technologies NaturalVue MFCL, CooperVision Biofinity sphere). Acuity and reading performance were evaluated. RESULTS A statistically significant difference in high-contrast distance acuity was observed (Biofinity, −0.18 ± 0.06; Biofinity MFCL, −0.14 ± 0.08; NaturalVue MFCL, −0.15 ± 0.03; repeated-measures [RM] ANOVA, P = .02). Under mesopic, high-contrast conditions, MFCLs performed worse than SVCLs (Biofinity, −0.05 ± 0.091; Biofinity MFCL, +0.03 ± 0.09; NaturalVue MFCL, +0.05 ± 0.091; RM-ANOVA, P < .0001). Under low-contrast conditions, MFCLs performed one line worse in photopic lighting and two lines worse under mesopic conditions (RM-ANOVA, P < .0001). Glare reduced acuity by 0.5 logMAR for all lenses (RM-ANOVA, P < .001). A statistically significant difference in near acuity was observed (RM-ANOVA, P = .02), but all lenses achieved acuity better than −0.1 logMAR (Biofinity, −0.16 ± 0.06; Biofinity MFCL, −0.17 ± 0.04; NaturalVue MFCL, −0.13 ± 0.08). Reading performance in words per minute (wpm) was worse with MFCLs (Biofinity MFCL, 144 ± 22 wpm; NaturalVue MFCL, 150 ± 28 wpm) than with SVCLs (156 ± 23 wpm; RM-ANOVA, P = .02) regardless of letter size (RM-ANOVA, P = .13). No difference in acuity between the MFCLs was detected (RM-ANOVA: all, P > .05). CONCLUSIONS Multifocal contact lenses perform similarly to SVCLs for high-contrast targets and display reduced low-contrast acuity and reading speed. Practitioners should recognize that high-contrast acuity alone does not describe MFCL visual performance.
SIGNIFICANCE:The contrast sensitivity (CS) function provides a more detailed assessment of vision than visual acuity. It was found that center-distance multifocal contact lens designs that are increasingly being prescribed for myopia control reduce distance photopic and mesopic CS in nonpresbyopic patients across a range of spatial frequencies. PURPOSE: This study aimed to determine the effect of center-distance multifocal soft contact lenses (MFCLs) on CS under photopic and mesopic conditions in nonpresbyopic patients. METHODS: Twenty-five myopic, nonpresbyopic adults were fitted binocularly with three lenses: Biofinity single vision contact lens (SVCL), Biofinity Multifocal D +2.50 add, and NaturalVue Multifocal in random order. Contrast sensitivity was measured at distance (4 m) under photopic and mesopic conditions and at near under photopic conditions. Log CS by spatial frequency and area under the log contrast sensitivity function (AULCSF) were analyzed between lenses.RESULTS: Distance photopic CS at each spatial frequency was higher with the SVCL than the MFCLs ( P < .001), but there was no difference between the MFCLs ( P = .71). Distance mesopic CS from 1.5 to 12 cycles per degree (cpd) was higher with the SVCL than the MFCLs (all P < .02); however, at 18 cpd, there was no difference in CS between NaturalVue and the SVCL ( P = .76), possibly because of spurious resolution. Photopic AULCSF for the SVCL was roughly 10% greater than both MFCLs. Contrast sensitivity at near was generally similar between lenses, only slightly lower with the NaturalVue at 11 and 15.5 cpd, but AULCSF at near was not different between lenses ( P > .05). CONCLUSIONS:Multifocal contact lenses reduce distance contrast sensitivity under both photopic and mesopic conditions. There is no clinically significant difference in near CS among all three lenses. These data show that MFCLs have effects on vision that are not captured by standard high-contrast visual acuity testing.
I read with interest the article by Gregory et al. 1 published in the American Academy of Optometry journal, Optometry and Vision Science. Although I applaud this endeavor, I find that the results are in question.I base this assertion on a few points in the Methods section of the article. First, the NaturalVue Fitting Guide was unfortunately not followed. The NaturalVue Multifocal fitting guide requires refraction to 20/15. Then, after normal binocular balance testing, the use of the duochrome test (binocularly) to put the patient "one step into green" is necessary. This last step was not followed (personal communication with one of the coauthors). Thus, the starting power generated via the NaturalVue Multifocal Quickstart calculator would not be accurate, as in this study they pushed maximum plus power, which is completely against the required fitting of NaturalVue Multifocal. It appears that the 10-minute wait before assessing distance vision was observed. However, we do not advise overrefraction to enhance vision but rather a change of on-eye lens power, based on subjective patient responses. Our pre-market evaluations found that the unique optical design of the NaturalVue Multifocal made it difficult for patients to note a difference when standard overrefraction techniques were used. The overrefraction adjusted maximum plus power to maximum distance visual acuity technique used in the study would therefore be erroneous in determining final contact lens powers for NaturalVue Multifocal.
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