The magnitude and distribution of open-loop accommodation using three different methods of opening the loop.
OBJECTIVE
The present study examines the magnitude, distribution, and relationship of open-loop accommodation obtained using the three most common methods of opening the accommodation loop.


METHODS
Open-loop accommodation was measured in 93 young, emmetropic subjects using a Canon R1 objective infrared optometer, and the accommodation loop was opened using the following methods: (1) dark empty field (DA), (2) bright empty field (BA), and (3) viewing a target through a small artificial pupil (PA).


RESULTS
PA was found to elicit significantly (p = 0.0001) higher values of open-loop accommodation than either DA or BA and demonstrated a much wider distribution of values than DA or BA. A further experiment demonstrated that the higher PA was attributable to the proximal effect of placing a small artificial pupil close to the eye.


CONCLUSIONS
Our results suggest that using a small artificial pupil to open the accommodation loop may not produce a veridical measure of open-loop accommodation.
Gray
L S
LS
Department of Vision Sciences, Glasgow Caledonian University, Scotland.
Strang
N C
NC
Winfield
N
N
Gilmartin
B
B
Winn
B
B
D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D003623:Dark Adaptation; D006801:Humans; D008027:Light; D009907:Optometry / Q000379:methods*; D011680:Pupil