Study on Visual Acuity according to the Illuminance in Presbyopes Wearing Center-Near Multifocal Contact Lenses

Abstract

Purpose : We investigated the changes in visual acuity and visual acuity according to illuminance in presbyopes wearing multifocal contact lenses.Methods : The subjects were 28 presbyopes (55.39±4.25 years) with a corrected visual acuity of 0.8 or more and astigmatism of less than 0.75 D. The Center-Near Multifocal contact lenses were worn in the period of 2 weeks for adaptation. The illuminance of test room was set to 1,000, 100, and 10 lx. The pupil size was measured at 3 m, and 40 cm with a pupil ruler when wearing multifocal contact lens (MFCL). Visual acuity at far and near was measured with high and low contrast ETDRS (Early Treatment Diabetic Retinopathy Study) chart.Results : When wearing MFCLs, high and low contrast visual acuity significantly increased as the illuminance increases at far and near distance (p 0.050), near visual acuities at 100 and 10 lx were significantly decreased (p<0.050) compared with spectacles. In 10 lx of low indoor illuminance with additional lamp, both near high and low contrast visual acuities were improved significantly (p<0.050).Conclusion : When wearing MFCLs, visual acuity was greatly affected by the illuminance, and the visual acuity in high illuminance condition was not different with spectacles. It was revealed that the additional near lamp could improve the visual acuity in dark indoor condition.