TY - JOUR
T1 - Electrophysiological and psychophysical studies of meridional anisotropies in children with and without astigmatism
AU - Yap, Tiong Peng
AU - Luu, Chi D.
AU - Suttle, Catherine M.
AU - Chia, Audrey
AU - Boon, Mei Ying
N1 - Funding Information:
The authors thank the parents and children for their participation, the colleagues at the Visual Electrophysiology Laboratory at Singapore National Eye Centre and Eye Clinic at KK Children’s and Women’s Hospital, and the Guide Dogs NSW/ACT for funding the development of the SOVS-CFEH Psychophysical Test Suite. Supported by the ARVO Publications Grant. Disclosure: T.P. Yap, None; C.D. Luu, None; C.M. Suttle, None; A. Chia, None; M.Y. Boon, None
© 2019 The Authors. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.
PY - 2019/5
Y1 - 2019/5
N2 - PURPOSE. We investigated the pattern of meridional anisotropies, if any, for pattern onset- offset visual evoked potential (POVEPs) responses and psychophysical grating acuity (GA) in children with normal letter visual acuity (20/20 or better). METHODS. A total of 29 children (aged 3-9 years), nine of whom were astigmatic (AS), were recruited. Orientation-specific monocular POVEPs were recorded in response to sinewave grating stimuli oriented along the subjects’ principal AS meridians. Horizontal and vertical gratings were designated Meridians 1 and 2, respectively, for nonastigmatic patients (Non-AS). Binocular POVEPs in response to the same stimuli, but oriented at 45°, 90°, 135°, and 180°, were recorded. Psychophysical GAs were assessed monocularly and binocularly along the same meridians using the same stimuli by a 2-alternative-forced-choice staircase technique. The C3 amplitudes and peak latencies of the POVEP and GAs were compared across meridians using linear mixed models (monocular) and ANOVA (binocular). RESULTS. There were significant meridional anisotropies in monocular C3 amplitudes regardless of astigmatism status (P = 0.001): Meridian 2 (mean ± SE Non-AS, 30.13 ± 2.07 µV; AS, 26.53 ± 2.98 µV) was significantly higher than Meridian 1 (Non-AS, 26.14 ± 1.87 µV; AS, 21.68 ± 2.73 µV; P = 0.019), but no meridional anisotropies were found for GA or C3 latency. Binocular C3 amplitude in response to horizontally oriented stimuli (180°, 29.71 ± 3.06 µV;) was significantly lower than the oblique (45°, 36.62 ± 3.05 µV; P = 0.03 and 135°, 35.95 ± 2.92 µV; P = 0.04) and vertical (90°, 37.82 ± 3.65 µV; P = 0.02) meridians, and binocular C3 latency was significantly shorter in response to vertical than oblique gratings (P ≤ 0.001). CONCLUSIONS. Meridional anisotropy was observed in children with normal vision. The findings suggest that horizontal gratings result in a small, but significantly lower POVEP amplitude than for vertical and oblique gratings.
AB - PURPOSE. We investigated the pattern of meridional anisotropies, if any, for pattern onset- offset visual evoked potential (POVEPs) responses and psychophysical grating acuity (GA) in children with normal letter visual acuity (20/20 or better). METHODS. A total of 29 children (aged 3-9 years), nine of whom were astigmatic (AS), were recruited. Orientation-specific monocular POVEPs were recorded in response to sinewave grating stimuli oriented along the subjects’ principal AS meridians. Horizontal and vertical gratings were designated Meridians 1 and 2, respectively, for nonastigmatic patients (Non-AS). Binocular POVEPs in response to the same stimuli, but oriented at 45°, 90°, 135°, and 180°, were recorded. Psychophysical GAs were assessed monocularly and binocularly along the same meridians using the same stimuli by a 2-alternative-forced-choice staircase technique. The C3 amplitudes and peak latencies of the POVEP and GAs were compared across meridians using linear mixed models (monocular) and ANOVA (binocular). RESULTS. There were significant meridional anisotropies in monocular C3 amplitudes regardless of astigmatism status (P = 0.001): Meridian 2 (mean ± SE Non-AS, 30.13 ± 2.07 µV; AS, 26.53 ± 2.98 µV) was significantly higher than Meridian 1 (Non-AS, 26.14 ± 1.87 µV; AS, 21.68 ± 2.73 µV; P = 0.019), but no meridional anisotropies were found for GA or C3 latency. Binocular C3 amplitude in response to horizontally oriented stimuli (180°, 29.71 ± 3.06 µV;) was significantly lower than the oblique (45°, 36.62 ± 3.05 µV; P = 0.03 and 135°, 35.95 ± 2.92 µV; P = 0.04) and vertical (90°, 37.82 ± 3.65 µV; P = 0.02) meridians, and binocular C3 latency was significantly shorter in response to vertical than oblique gratings (P ≤ 0.001). CONCLUSIONS. Meridional anisotropy was observed in children with normal vision. The findings suggest that horizontal gratings result in a small, but significantly lower POVEP amplitude than for vertical and oblique gratings.
KW - Astigmatism
KW - Horizontal effect
KW - Meridional anisotropy
KW - Oblique effect
KW - Refractive error
KW - Vision, Binocular/physiology
KW - Humans
KW - Child, Preschool
KW - Male
KW - Astigmatism/diagnosis
KW - Visual Acuity
KW - Psychophysics/methods
KW - Anisotropy
KW - Evoked Potentials, Visual/physiology
KW - Female
KW - Pattern Recognition, Visual/physiology
KW - Child
KW - Orientation/physiology
UR - http://www.scopus.com/inward/record.url?scp=85065550061&partnerID=8YFLogxK
U2 - 10.1167/iovs.18-25924
DO - 10.1167/iovs.18-25924
M3 - Article
C2 - 31042798
AN - SCOPUS:85065550061
SN - 0146-0404
VL - 60
SP - 1906
EP - 1913
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 6
ER -