title: 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 &lt; 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 &lt; 0.0001). Best-focus shift upon induced astigmatism was significantly different across groups, both for natural aberrations and AO-correction (p &lt; 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.forename: Susana
authors.initials: S
authors.lastname: Marcos
authors.forename: Miriam
authors.initials: M
authors.lastname: Velasco-Ocana
authors.forename: Carlos
authors.initials: C
authors.lastname: Dorronsoro
authors.forename: Lucie
authors.initials: L
authors.lastname: Sawides
authors.forename: Martha
authors.initials: M
authors.lastname: Hernandez
authors.forename: Gildas
authors.initials: G
authors.lastname: Marin
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology*; D057108:Corneal Wavefront Aberration / Q000503:physiopathology*; D058453:Emmetropia / Q000502:physiology*; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology*; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult