Impact of astigmatism and high-order aberrations on subjective best focus.

Abstract

We studied the role of native astigmatism and ocular aberrations on best-focus setting and its shift upon induction of astigmatism in 42 subjects (emmetropes, myopes, hyperopes, with-the-rule [WTR] and against-the-rule [ATR] myopic astigmats). Stimuli were presented in a custom-developed adaptive optics simulator, allowing correction for native aberrations and astigmatism induction (+1 D; 6-mm pupil). Best-focus search consisted on randomized-step interleaved staircase method. Each subject searched best focus for four different images, and four different conditions (with/without aberration correction, with/without astigmatism induction). The presence of aberrations induced a significant shift in subjective best focus (0.4 D; p < 0.01), significantly correlated (p = 0.005) with the best-focus shift predicted from optical simulations. The induction of astigmatism produced a statistically significant shift of the best-focus setting in all groups under natural aberrations (p = 0.001), and in emmetropes and in WTR astigmats under corrected aberrations (p < 0.0001). Best-focus shift upon induced astigmatism was significantly different across groups, both for natural aberrations and AO-correction (p < 0.0001). Best focus shifted in opposite directions in WTR and ATR astigmats upon induction of astigmatism, symmetrically with respect to the best-focus shift in nonastigmatic myopes. The shifts are consistent with a bias towards vertical and horizontal retinal blur in WTR and ATR astigmats, respectively, indicating adaptation to native astigmatism.

• Authors: Susana Marcos, Miriam Velasco-Ocana, Carlos Dorronsoro, Lucie Sawides, Martha Hernandez, Gildas Marin
• Journal: Journal of vision (J Vis) Vol. 15 Issue 11 Pg. 4 (Aug 01 2015) ISSN: 1534-7362 [Electronic] United States
• PMID: 26237300 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Adaptation, Physiological
• Adult
• Astigmatism (physiopathology)
• Corneal Wavefront Aberration (physiopathology)
• Emmetropia (physiology)
• Fixation, Ocular (physiology)
• Humans
• Hyperopia (physiopathology)
• Male
• Middle Aged
• Myopia (physiopathology)
• Refraction, Ocular (physiology)
• Visual Acuity (physiology)
• Young Adult