Quality of Life in Presbyopes with Low and High Myopia Using Single-Vision and Progressive-Lens Correction.

This study evaluates the impact of the severity of myopia and the type of visual correction in presbyopia on vision-related quality of life (QOL), using the refractive status and vision profile (RSVP) questionnaire. A total of 149 subjects aged 41-75 years with myopic presbyopia were recruited: 108 had low myopia and 41 had high myopia. The RSVP questionnaire was administered. Rasch analysis was performed on five subscales: perception, expectation, functionality, symptoms, and problems with glasses. Highly myopic subjects had a significantly lower mean QOL score (51.65), compared to low myopes (65.24) (p < 0.001). They also had a significantly lower functionality score with glasses (49.38), compared to low myopes (57.00) (p = 0.018), and they had a worse functionality score without glasses (29.12), compared to low myopes (36.24) (p = 0.045). Those who wore progressive addition lenses (PAL) in the high-myope group (n = 25) scored significantly better, compared to those who wore single-vision distance (SVD) lenses (n = 14), with perception scores of 61.19 and 46.94, respectively (p = 0.029). Highly myopic presbyopes had worse overall QOL and functionality, both with and without glasses, compared to presbyopes with low myopia. High-myopic PAL users had a better perception outcome than SVD lens wearers. Low-myopic PAL wearers had a better QOL than SVD wearers.

Shape discrimination thresholds among subjects with emmetropia and corrected myopia.

BACKGROUND: Myopia is highly prevalent in some Asian countries yet the ability of subjects with myopia to discriminate shapes using radial frequency (RF) patterns­circular patterns that are defined by sinusoidal modulation of the radius in polar coordinates­is not well documented. In this psychophysical study, we explore the relative ability of subjects with corrected myopia to discriminate shapes using radial frequency patterns. Specifically, the aims were to find if there are any differences in modulation detection thresholds among subjects with emmetropia and corrected myopia and to establish thresholds as a function of myopic refractive error. METHODS: Shape discrimination thresholds were measured for subjects with emmetropia (n = 20) and corrected myopia (n = 20) using circular D4 (fourth derivative of Gaussian) radial frequency patterns. A total of five radial frequency patterns (RF1 to RF16) with peak spatial frequencies of 2, 4, 6 and 8 (SF2 to SF8) cycles per degree were studied. The radial frequency suffix determines the number of deformation cycles present around the circumference, while the peak spatial frequency is related to the thickness of the circular contour. RESULTS: Overall, shape discrimination thresholds were not significantly different (p > 0.05) between subjects with emmetropia and corrected myopia. Similarly, there was no significant correlation (p > 0.05) in thresholds with the magnitude of corrected myopia. Shape discrimination performance was best for RF8 patterns, with thresholds ranging from nine to 12 seconds of arc for SF2 to SF6 patterns and from 20 to 22 seconds of arc for SF8 patterns. Thresholds were significantly higher (p < 0.05) for SF8 patterns compared to the other spatial frequency patterns (SF2 to SF6) for all radial frequency patterns. The average thresholds increased by about 1 to 1.5 log units from RF1 to RF4 and RF8. CONCLUSION: Across all patterns studied here, shape discrimination thresholds remain at hyperacuity levels and are not degraded in subjects with corrected myopia compared to emmetropia.

Enhanced contrast sensitivity confirms active compensation in blur adaptation.

PURPOSE: To determine the effects of defocus-induced blur adaptation on human contrast sensitivity (CS) function. METHODS: Defocused (+2 D) CS was measured for spatial frequencies between 0.5 and 12 cycles per degree (cpd) before and after adaptation to +2 D blur in six subjects with normal vision. During the 30-minute adaptation period with +2 D lens, subjects were exposed to a succession of static calibrated natural images that were also used to "top-up" adaptation between postadaptation trials. RESULTS: After 30 minutes of blur adaptation, CS was found to be significantly reduced at 0.5 cpd (P = 0.023), though it was enhanced at 8 cpd (P = 0.007) and 12 cpd (P = 0.005). The average sensitivity reduction at 0.5 cpd was 0.20 log(10) units, whereas enhancements were 0.09 and 0.16 log(10) units at 8 and 12 cpd, respectively. CONCLUSIONS: The present study demonstrates a novel finding that 30 minutes of defocused viewing results in enhanced high spatial frequency CS. The concurrent observation of low spatial frequency CS reduction suggests that the changes are not caused by simple learning effects but are likely caused by neural adaptation.