Gain and movement time of convergence-accommodation in preschool children.
BACKGROUND
Convergence-accommodation is the synkinetic change in accommodation driven by vergence. A few studies have investigated the static and dynamic properties of this cross-link in adults but little is known about convergence-accommodation in children. The purpose of this study was to develop a technique for measuring convergence-accommodation and to study its dynamics (gain and movement time) in a sample of pre-school children.


METHODS
Convergence-accommodation measures were examined on thiry-seven normal pre-school children (mean age = 4.0 +/- 1.31 yrs). Stimulus CA/C (sCA/C) ratios and movement time measures of convergence-accommodation were assessed using a photorefractor while subjects viewed a DOG target. Repeated measures were obtained on eight normal adults (mean age = 23 +/- 0.2 yrs).


RESULTS
The mean sCA/C ratios and movement times were not significantly different between adults and children (0.10 D/Delta [0.61 D/M.A.], 743 +/- 70 ms and 0.11 D/Delta [0.50 D/M.A.], 787 +/- 216 ms). Repeated measures on adults showed a non-significant mean difference of 0.001 D/Delta.


CONCLUSIONS
The results suggest that the possible differences in crystalline lens (plant) characteristics between children and adults do not appear to influence convergence-accommodation gain or duration.
Suryakumar
R
R
School of Optometry, University of Waterloo, Waterloo, Ontario, Canada. rsuryaku@uwaterloo.ca
Bobier
W R
WR
D000065:Accommodation, Ocular / Q000502:physiology*; D000328:Adult; D000375:Aging / Q000502:physiology; D002675:Child, Preschool; D003290:Convergence, Ocular / Q000502:physiology*; D006801:Humans; D010775:Photic Stimulation / Q000379:methods; D015203:Reproducibility of Results; D013997:Time Factors