Perceptual impact of astigmatism induction in presbyopes

• Published in: Vision research (Oxford) Vol. 165; pp. 143 - 151
• Main Authors: Benedi-Garcia, Clara, Velasco-Ocana, Miriam, Dorronsoro, Carlos, Pascual, Daniel, Hernandez, Martha, Marin, Gildas, Marcos, Susana
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2019
• Subjects: Aberration; Adaptation; Adult; Astigmatism; Astigmatism - physiopathology; Best focus; Female; Humans; Male; Middle Aged; Presbyopia; Presbyopia - physiopathology; Presbyopia correction; Refraction; Refraction, Ocular - physiology; Vision Tests; Visual Acuity; Visual Perception - physiology; Young Adult; Refraction; Presbyopia correction; Presbyopia; Best focus; Aberration; Astigmatism; Adaptation
• ISSN: 0042-6989; 1878-5646; 1878-5646
• DOI: 10.1016/j.visres.2019.10.008

We investigated the effect of induced astigmatism on subjective best focus and on visual acuity in 28 subjects of different ages (pre-presbyopic and presbyopic) and with different refractive profiles (emmetropes and astigmats). Measurements were performed using a custom-developed Adaptive Optics system, which allowed correction of high order aberrations and induction of astigmatism (0.5, 1, 1.5 and 2.0 D; axis: 180°, 45° and 22.5°). Upon induction of astigmatism, best focus shifted towards negative values in pre-presbyopic emmetropic eyes (by −0.14 D for 0.5 D and by −0.33 D for 2.0 D), while it shifted towards positive values in presbyopes, both in emmetropic presbyopes (by +0.04 D for 0.50 D and by +0.16 D for 2.0 D) and in astigmatic presbyopes (by +0.23 D for 0.50 D and by +0.40 D for 2.0 D). Also, visual acuity was most sensitive to astigmatism induction in pre-presbyopic emmetropes and least sensitive in presbyopes, particularly when high order aberrations were corrected: visual acuity ratio with/without astigmatism was: 0.74/0.85/0.98 (for astigmatism induced at 180°) and 0.68/0.73/0.86 at 45°, for pre-presbyopic emmetropes/presbyopic emmetropes/presbyopic astigmats. These findings may be connected to long term exposure to astigmatism in astigmats and corrected presbyopes.