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A.S. Rajagopalan, E.S. Bennett, V. Lakshminarayanan, V. Henry; Performance of Presbyopic Contact Lenses Under Mesopic Conditions . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3679.
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Purpose: To assess visual performance of RGP multifocals, soft bifocals, and RGP monovision under mesopic conditions. Methods: 32 subjects (26 females and 6 males) between the ages of 42 and 65 years with an average of 51.5 ± 6.4 years participated in this study. The mean presbyopic add was 2.02 ± 0.5 D. The study included subjects wearing monovision, Acuvue (Johnson & Johnson) bifocals, RGP Essentials (Blanchard) multifocals and progressive addition lenses (PAL), with PAL wearers forming the control group. All subjects participated in a screening for their visual adaptive system using the dark adaptometer. Low (10%) and high (90%) contrast acuities were recorded using the Bailey-Lovie chart. Measurements of contrast sensitivity using the Vistech 6500 system and glare sensitivity using the Brightness Acuity Tester (BAT) were made. Results: RGP multifocals provided the best high and low contrast acuity (-0.20, -0.013 log MAR units respectively) followed by soft bifocal lenses (-0.08, 0.138 log MAR units respectively). High and low contrast acuity in monovision wearers was determined to be 0.10 and 0.263 log MAR units respectively. It was observed that RGP bifocal contact lens wearers experienced the lowest amount of disability glare, followed by soft bifocal wearers and PAL wearers. Monovision wearers, in general, experienced the maximum amount of disability glare. Significant differences with T tests were obtained with BAT between monovision and soft bifocals at all the three glare levels (p<0.001). Monovision and RGP bifocal wearers also showed significant differences (p<0.001) at all three glare levels. RGP bifocal contact lens wearers had the highest contrast sensitivity at all the spatial frequencies. Soft bifocal contact lens wearers exhibited superior contrast sensitivity than monovision wearers at all spatial frequencies. The CSF was fit to an equation with three parameters, one (a) influencing the low frequency behavior of the function, (b) describing the contrast sensitivity peak and (c) expressing the high frequency behavior of the function. The area under the CSF curve was also calculated. An index of visual performance based on contrast sensitivity was obtained. RGP multifocals have the best visual function at an index of 0.985, soft bifocals have an index of 0.659, and monovision has an index of 0.595. Conclusions: From the results of our study, we conclude that RGP multifocals perform best under mesopic light levels. Overall, our results show that all our subjects wearing RGP multifocals, soft bifocals, monovision and PAL have good contrast sensitivity, satisfactory low and high contrast acuity and reduced glare sensitivity.
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