ACCURACY OF MONOCULAR VS BINOCULAR ACCOMMODATION FOR STEPPED CHANGES IN ACCOMMODATIVE DEMAND

Title ACCURACY OF MONOCULAR VS BINOCULAR ACCOMMODATION FOR STEPPED CHANGES IN ACCOMMODATIVE DEMAND
Author, Co-Author Helene Kergoat, John Lovasik O.D., Barbara Houde
Topic
Year
1992
Day
Monday
Program Number
2:15 pm
Room
Ireland B
Affiliation
Abstract The synkinesis between the accommodative (acc've) and vergence systems predicts that one may influence the responsivity of the other. Anomalous binocular motility or fusional stress may over or underdrive accommodation (acc'n) and blur vision. Conversely, acc've performance may normalize and vision clear in the presence of imperfect binocularity when acc've performance is assessed monocularly. Here, we compared the dynamic and static acc've performance for monocular (mono.) and binocular (bino.) fixation of black on white hard copy 0.75m letters viewed at 40cm. 20 volunteers (age 22.6 yrs,SD 3.6) with good visual acuity and binocularity participated in two, 1 hr sessions. The acc've response was sampled at 1 Hz over a 1 min interval with a computerized laser speckle Badal optometer. The acc've stimulus was modified via positive or negative lenses incremented before the eye(s) in 0.25D steps, from 0.00 to +4.00D, then from 0.00 to -4.00D. For both mono. and bino. viewing, positive lenses caused acc'n to relax in accordance with the lens power up to about 1.00D. Thereafter, acc'n progressively fell behind the dioptric demand. For negative lenses, 16 subjects accommodated in tandem with the acc've demand while 4 subjects showed a progressive lag in the acc've response with increasing lens power during bino. testing. Under mono. conditions the acc'n followed more closely the stepwise change in the acc've demand (p= 0.0043). However, mono. acc've responses showed a greater lead than the bino. counterpart (p= 0.0001). Our results are discussed in terms of their clinical utility and implications for the management of job related visual fatigue.
Affiliation of Co-Authors
Outline