Program#/Poster#: 5404
Abstract Title: Early Dark Adaptation: Effect of Age
Presentation Start/End Time:
Location: Palm A
Reviewing Code: 103 adaptation - VI
Author Block: K.E. Higgins1, J.M. White2,
D.Cades3, V.Ciaccio2, L.Liu1. 1Arlene
R Gordon Research Inst, Lighthouse International, New York, NY; 2VA
NJHCS, East Orange, NJ; 3George Mason University, Fairfax, VA.
Keywords: 413 aging: visual performance, 412 aging
Purpose: Sturr et
al. (1991) reported that older, compared to younger, subjects (Ss) evidenced a
slower recovery of sensitivity during the first second after the offset of a
relatively intense pre-adapting field that would have produced appreciable
bleaching of cone photopigment. In contrast, we
(unpublished data) did not find any age difference when recovery was measured
following exposure to a relatively moderate intensity, transient (1 sec.
duration), peripheral, glare source Our objective was to determine if an age-dependent
delay in early dark adaptation would occur at moderate light levels if the
exposure was continuous instead of transient.
Methods: Twelve young (24.8±2.7 yrs) and 10 elderly (60.9±7.5
yrs) Ss in good ocular health with VA > 20/40 participated. Ss were
initially pre-adapted for 7 minutes to a 12o diameter, 150 cd/m2
white adapting field (AF) with a small, dim, central fixation light.
Subsequently, AF luminance was abruptly decreased to 1 cd/m2 for a duration of 2 seconds on each trail and then returned to
150 cd/m2 for the remainder of the trial. Over a series of trials,
early dark adaptation thresholds were measured at several times (from 20 - 700 msec) after the AF decrement using a 2-alternative, spatial
forced choice procedure. On each trial, a 45 arcmin,
20 msec test flash was presented either above or
below the central fixation light. Also, steady-state (SS) thresholds were
measured following 7 minutes of continuous adaptation to AF levels of 150 and 1
cd/m2.
Results: A 2-way ANOVA showed a) the effect of age was
significant, with thresholds being higher for the older Ss; b) the effect of
time after AF luminance decrement was significant, with threshold decreasing
with increased time in the dark for all subjects; c) the time by age interaction
was also significant, indicating that recovery during early dark adaptation was
significantly slower in the elderly sample.
Conclusions: Result “a” is consistent with earlier research.
Result “b” is consistent with the work of Sturr et
al., and, further, it suggests that our previous failure to observe an
age-dependent difference in early dark adaptation, was due, at least in part,
to the transient character of the pre-adapting field used in that study.
Commercial Relationship: K.E. Higgins,
None; J.M. White, None; D. Cades, None; V. Ciaccio, None; L. Liu, None.
Support: VA Grant C2833R