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. 2023 May 6:15:105-117.
doi: 10.2147/OPTO.S405472. eCollection 2023.

Effects of Lens-Induced Astigmatism at Near and Far Distances

Silvia Tavazzi  1   2 , Natalia Vlasak  3 , Fabrizio Zeri  1   2   4
Affiliations

Effects of Lens-Induced Astigmatism at Near and Far Distances

Silvia Tavazzi et al. Clin Optom (Auckl). .

Abstract

Purpose: To investigate and compare the degradation of visual acuity (VA) in myopic presbyopes due to lens-induced astigmatism at near and at far distance.

Patients and methods: Fourteen corrected myopic presbyopes were recruited. VA (logarithm of the minimum angle of resolution) was measured binocularly for different conditions of lens-induced astigmatism: cylindrical powers of -0.25, -0.50, -0.75, -1.00, -1.50, and -2.00 diopters (and positive spherical power of half the cylindrical power) with two axis orientations (with-the-rule WTR and against-the-rule ATR) were added to their optical correction. Measurements were carried out at far and near distance both in photopic and mesopic conditions, and for high and low contrast (HC/LC) stimuli. The paired Wilcoxon signed-rank statistics test was used to evaluate difference between conditions.

Results: The measured VA as a function of the lens-induced astigmatism was described by regression lines in all investigated experimental conditions. The angular coefficients (slopes) of these lines represent the VA degradation, ie, the variation in logMAR corresponding to the addition of 1.00 diopters of cylindrical power. In photopic HC conditions, the VA degradation is significantly more pronounced at far distance than at near distance (0.22±0.06 diopters-1 vs 0.15±0.05 diopters-1, p = 0.0061 in WTR conditions; 0.18±0.06 diopters-1 vs 0.12±0.05 diopters-1, p = 0.0017 in ATR conditions), although VAs at near and at far with zero cylinder were similar (-0.14±0.10 vs -0.14±0.08, p = 0.824).

Conclusion: The better tolerance to lens-induced astigmatism blur at near than at far distance in photopic conditions with HC stimuli is tentatively attributed to a possible experience-mediated neural compensation associated to the tendency of the eye toward an inherent astigmatism at near.

Keywords: blur; cylindrical power; myopic presbyopes; visual acuity.

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Conflict of interest statement

The authors have no proprietary interest in any of the materials mentioned in this article. NV is an employee of Hoya Vision Care. The project was partially funded by Hoya Vision Care. The authors report no other conflicts of interest in this work.

Figures

Figure 1
Figure 1
Scheme of the study design showing the conditions under which VA was measured, ie at far and at near distance, in photopic and mesopic conditions, at high contrast and low contrast, and for six different level of power and two different axis orientations of the added cylindrical lens.
Figure 2
Figure 2
Visual acuity (logMAR) of one participant measured at far and at near distance, in photopic (full markers) and mesopic (empty markers) conditions, for HC (squares) and LC (diamonds) stimuli at different levels of induced WTR and ATR astigmatism. The continuous lines show the results of the linear regressions of the data.
Figure 3
Figure 3
(a) Mean slopes indicating the visual acuity (A) drop induced by astigmatism (WTR and ATR) at far and at near distance, for HC and LC stimuli, in photopic and mesopic conditions. (b) Mean DoF calculated as one tenth of the reciprocal of the slopes, thus representing the cylindrical power which produces a 0.1 logMAR worsening of the visual acuity. The bars indicate the standard deviations of the data.
See this image and copyright information in PMC

References

    1. Ohlendorf A, Tabernero J, Schaeffel F. Visual acuity with simulated and real astigmatic defocus. Optom Vis Sci. 2011;88:562–569. doi:10.1097/OPX.0b013e31821281bc - DOI - PubMed
    1. Sharma N, Pangtey MS, Vajpayee RB, et al. Surgically induced astigmatism after laser in situ keratomileusis for spherical myopia. J Refract Surg. 2002;18:239–244. doi:10.3928/1081-597X-20020501-05 - DOI - PubMed
    1. Marcos S, Rosales P, Llorente L, Jimenez-Alfaro I. Change in corneal aberrations after cataract surgery with 2 types of aspherical intraocular lenses. J Cataract Refract Surg. 2007;33:217–226. doi:10.1016/j.jcrs.2006.10.021 - DOI - PubMed
    1. Barbero S, Marcos S, Merayo-Lloves J, Moreno-Barriuso E. Validation of the estimation of corneal aberrations from videokeratography in keratoconus. J Refract Surg. 2002;18:263–270. doi:10.3928/1081-597X-20020501-09 - DOI - PubMed
    1. Villegas EA, Artal P. Spatially resolved wavefront aberrations of ophthalmic progressive-power lenses in normal viewing conditions. Optom Vis Sci. 2003;80:106–114. doi:10.1097/00006324-200302000-00006 - DOI - PubMed