In most subjects, astigmatism less than 0.5 D did not degrade visual acuity. This suggests that under clinical conditions, the visual benefit of precise correction of astigmatism less than 0.5 D would be limited.

No significant correlations were found between VA measurements and the optical quality of the eye in young subjects with normal or excellent spatial vision. Some subjects with normal degrees of aberrations attained excellent VA.

PurposeTo clinically validate an adaptive optics visual simulator (VAO) that measures subjective refraction and visual acuity.SettingOptics Laboratory, University of Murcia, Murcia, Spain.DesignProspective case series.MethodsUsing the adaptive optics visual simulator, 2 examiners measured the subjective refraction and visual acuity in healthy eyes of volunteers; 1 examiner also used a trial frame as a gold standard. The interexaminer reproducibility and agreement with the gold standard were estimated using the following statistical parameters: limits of agreement from Bland-Altman analysis, significance between differences (P value), and intraclass correlation coefficient (ICC).ResultsSeventy-six eyes of 38 volunteers were measured. Interexaminer reproducibility for subjective refraction was excellent (ICC ≥0.96; P > .05), with low 95% confidence interval (CI) values for the power vectors M (spherical equivalent of the given refractive error), J0 (Jackson cross-cylinder, axes at 180 degrees and 90 degrees), and J45 (Jackson cross-cylinder, axes at 45 degrees and 135 degrees) (±0.51 diopter [D], ±0.14 D, and ±0.14 D, respectively). No significant differences in subjective refraction and visual acuity were found between the visual simulator and gold standard (P > .05), with 95% CIs for M, J0, and J45 (subjective refraction) of ±0.67 D, ±0.14 D, and ±0.16 D, respectively, and a ±0.10 logarithm of the minimum angle of resolution (visual acuity).ConclusionSubjective refraction results using the adaptive optics visual simulator agreed with those of the gold standard and can be used as the baseline for visual simulation of any optical corneal profile or intraocular lens design for refractive surgery patients.

PURPOSE: To evaluate the use of the VAO adaptive optics visual simulator (Voptica SL, Murcia, Spain) for customization of spherical aberration to increase depth of focus. METHODS: Through-focus visual acuity with both high- and low-contrast letters from +1.00 to −3.00 diopters (D) was measured in 17 dilated eyes with three different induced amounts of spherical aberration for a 4.5-mm pupil diameter: control (0 µm), −0.15 µm, and −0.30 µm. RESULTS: The defocus curves followed the same behavior with both values of contrast, but the visual acuity was 0.2 logMAR lower with low contrast. The mean values of high-contrast logMAR visual acuity at far, intermediate (67 cm), and near (40 cm) were −0.10, 0.11, and 0.37 for control, 0.04, 0.00, and 0.15 for −0.15 µm, and 0.23, 0.00, and 0.06 for −0.30 µm conditions. The 95% confidence interval ranged from ±0.14 to ±0.45 logMAR and the middle 50% of the distribution was approximately 0.2 logMAR. CONCLUSIONS: Negative values of spherical aberration extend the depth of focus in different ways depending on each patient. The VAO is a new instrument that allows the visual customization of spherical aberration to enhance depth of focus. [ J Refract Surg . 2020;36(4):223–229.]

Changes in corneal optics have been measured after downward gaze. However, ocular aberrations during downward gaze have not been previously measured. A commercial Shack-Hartmann aberrometer (COAS-HD) was modified by adding a relay lens system and a rotatable beam splitter to allow on-axis aberration measurements in primary gaze and downward gaze with binocular fixation. Measurements with the modified aberrometer (COAS-HD relay system) in primary and downward gaze were validated against a conventional aberrometer. In human eyes, there were significant changes (p<0.05) in defocus C(2,0), primary astigmatism C(2,2) and vertical coma C(3,−1) in downward gaze (25 degrees) compared to primary gaze, indicating the potential influence of biomechanical forces on the optics of the eye in downward gaze. To demonstrate a further clinical application of this modified aberrometer, we measured ocular aberrations when wearing a progressive addition lens (PAL) in primary gaze (0 degree), 15 degrees downward gaze and 25 degrees downward gaze.

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Recently, computer numerically controlled machines have permitted the manufacture of progressive power lenses (PPLs) with different designs. However, the possible differences in optical performance among lens designs are not yet well established. In this work, the spatially resolved aberrations, at 20 relevant locations, of three PPLs with different designs were measured with a Hartmann-Shack wavefront sensor. The wavefront aberration (WA), its root mean square error (RMS) and the point-spread function were obtained. Spatially resolved plots are shown for all aberrations, astigmatism alone, and for higher order aberrations. The average RMS of all zones is also compared, and the standard deviation is used as a parameter to evaluate the level of hard-soft design. We find differences in the spatial distribution of the aberrations but not in the global RMS, indicating that current PPLs are rather similar to a waterbed, with the aberrations being the water: they can be moved but they cannot be eliminated.