Static vergence and accommodation: population norms and orthoptics effects

Doc Ophthalmol. 1986 Feb 28;62(2):165-79. doi: 10.1007/BF00229128.


The steady-state characteristics of the accommodation and vergence systems can be described by a model with six major oculomotor parameters. These include the system biases (tonic vergence and accommodation) and forward-loop gains (vergence and accommodative gains), as well as the interactive system gains (AC/A and CA/C ratios). We investigated these parameters in two populations: (1) 22 visually-normal asymptomatic individuals, and (2) 21 visually-abnormal symptomatic individuals before and after conventional orthoptic therapy. Two parameters related to system gain differentiated between the symptomatic and asymptomatic individuals: the slope of the fixation disparity curve with accommodation open-looped and the slope of the accommodative response/stimulus curve. Following orthoptic therapy, 4 static model parameters and 1 dynamic clinical parameter showed changes toward the normal mean; this included tonic accommodation, slope of the fixation disparity curve with accommodation closed-loop (2.5D), slope of the accommodative response/stimulus curve, the CA/C ratio, and the +/- 2D monocular accommodative flipper rate.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Accommodation, Ocular*
  • Adolescent
  • Adult
  • Convergence, Ocular*
  • Evaluation Studies as Topic
  • Eye Movements*
  • Humans
  • Orthoptics / methods*
  • Reference Values
  • Vision Disorders / physiopathology
  • Vision Disorders / therapy
  • Vision Tests / instrumentation