To compare the capability of objective measures of visual acuity (potential visual acuity from C-scan) to predict subjective visual acuity (best spectacle-corrected visual acuity [BSCVA]).Patients with BSCVA > or = 20/20 were enrolled in four groups (Group 1: normal [33 eyes]; Group 2: < -7.00 D myopia [43 eyes]; Group 3: > or = -7.00 D myopia [28 eyes]; Group 4: At least 1 month after LASIK [93 eyes]). Videokeratography was performed with the ray tracing Technomed C-scan. The potential visual acuity from C-scan was obtained with pupils undilated and intact precorneal tear films. All visual acuity was recorded in logMAR, and the significance of differences between acuities was assessed with a one-way ANOVA test.The potential visual acuity from C-scan ray tracing of normal and myopic eyes in response to both photopic and mesopic stimuli did not differ. In a given eye, the potential visual acuity from C-scan ray tracing was better than BSCVA, and the difference was statistically significant. Although the potential visual acuity from C-scan of postoperative LASIK eyes in response to photopic stimuli was the same, it decreased under mesopic conditions.Potential visual acuity from C-scan overestimates subjective visual acuity due to the inadequate assumptions in ray tracing or individual retinal resolution ability. In addition, the potential visual acuity from C-scan ray tracing varies with pupil diameter in different illumination.

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individual retinal resolution subjective visual acuity oneway anova bscva photopic cscan ray tracing

Show-Chuan, Tsai I-Jong, Wang Shiow-Wen, Liou Wei-Li, Chen Yuan-Chieh, Lee Gow-Lieng, Tseng Fung-Rong, Hu,.Comparison of subjective visual acuity with visual acuity predicted from C-scan topography.. 19 (2),137-41.

Show-Chuan, Tsai I-Jong, Wang Shiow-Wen, Liou Wei-Li, Chen Yuan-Chieh, Lee Gow-Lieng, Tseng Fung-Rong, Hu,"Comparison of subjective visual acuity with visual acuity predicted from C-scan topography." 19

Show-Chuan, Tsai I-Jong, Wang Shiow-Wen, Liou Wei-Li, Chen Yuan-Chieh, Lee Gow-Lieng, Tseng Fung-Rong, Hu,"Comparison of subjective visual acuity with visual acuity predicted from C-scan topography."