The purpose of this study is to compare peripheral higher order aberrations in young
and old emmetropic eyes across the horizontal (±40°) and inferior (–20°) visual field.
People with central visual field loss use eccentric fixation for various visual tasks.
Recently studies have shown that the correction of lower order aberrations (defocus &
astigmatism) can improve eccentric vision in subjects with central visual field loss
(CFL). The CFL subjects mostly correspond to older age groups who use eccentric
fixation angles up to 20°–30°. While there have been studies comparing the off-axis
lower order aberrations in normal young and old subjects, there is only one recent
study, which has compared off-axis higher order aberrations in normal young and old
emmetropic eyes up to 20° (horizontal and vertical) eccentricity. In this study we
have measured off-axis aberrations in a group of 10 young (23 ± 3 years) and 10 old
(57 ± 4 years) emmetropes. The aberrations of the right eye were measured using
COAS-HD VR Hartmann-Shack aberrometer in steps 10° out to ± 40° horizontally and
–20° inferiorly in the visual field. Subjects rotated the eyes to view the fixation targets,
which were red light emitting diodes, placed at 3 meter from the eye. The aberrations
were quantified for a pupil area 5 mm in diameter.
Mixed between-within subject’s analysis of variance of the horizontal coma C13
showed that there was a statistically significant difference between age groups
(p<0.05). The coma increased linearly in both groups from nasal to temporal visual
field. The rate of change was greater in the old (slope = –0.027 μm/deg) compared
to the young (slope = –0.012 μm/deg) emmetropes. In the inferior visual field,
vertical coma C-13 changed linearly in both groups with higher values in old (slope =
0.015 μm/deg) compared to young (slope = 0.006 μm/deg). The mean spherical
aberration was positive in older emmetropes (0.053 μm) compared to young
emmetropes (-0.030 μm). The HO RMS showed a quadratic increase in the
periphery for both age groups. The HO RMS was greater in older emmetropes but it
was not statistically significant (p>0.05) when compared to young emmetropes.
Our results show that there is an increase in coma, spherical aberration, and HO
RMS with age in the periphery.