The Relationship Between the Type and Central Slope of the Fixation Disparity Curve and Symptoms

Authors

  • A.A. Yekta
  • L.D. Pickwell
  • T.C.A. Jenkins

DOI:

https://doi.org/10.65636/cjo.v51i4.7037

Keywords:

slope, fixation disparity curve, symptoms

Abstract

A modified near Mallett unit was used for generating forced vergence fixation disparity curves in 84 symptomatic and 50 symptom-free patients. The central slope of the curves was calculated for each patient. No significant difference was found between the symptomatic and symptom-free groups with respect to the type and central slope of the curves.

References

1. Amer, R.S., Berger, S.I., Braverman, G. and Kaplan, M. The clinical significance of the effect of vergence on fixation disparity-a preliminary investigation. Am. J. Optom. Arch. Am. Acad. Optom. 33: 399-409, 1956. DOI: https://doi.org/10.1097/00006324-195608000-00001

2. Ogle, K.N., Martens, T.G., Dyer, J.A. Oculomotor imbalance in binocular vision and fixation disparity. Henry Kimpton, London, 39-141, 1967.

3. Sheedy, J.E. and Saladin, J.J. Association of symptoms with measure of oculomotor deficiency. Am. J. Optom. Physiol. Opt. 55: 670--676, 1978. DOI: https://doi.org/10.1097/00006324-197810000-00002

4. Sheedy, J.E. Fixation disparity analysis of oculomotor imbalance. Am. J. Optom. Physio/. Opt. 57: 1074-1084, 1980. DOI: https://doi.org/10.1097/00006324-198009000-00014

5. Teitelbaum, B.A., Micca, P.J., Jone, G. D., Thum, M. and Lee, T. Differentia­tion of asymptomatic patients from sympt DOI: https://doi.org/10.1097/00006324-198504000-00007

6. Lyons, J.G. Retinal slip in clinical prac­tice. The Optician 130: 29 and 81, 1955.

7. Carter, D.B. Parameters of fixation dispar­ity. Am. J. Optom. Physiol. Opt 57: 610--617, 1980. DOI: https://doi.org/10.1002/j.2330-9512.1980.tb02845.x

8. Pickwell, L.D. Significance of the central binocular lock in fixation disparity and associated 'phoria. Transactions First· lntenuJtional Congress of the British College of Optometrists. L: I 08-113, London, 1984.

9. Wildsoet, C.F. and Cameron, K.D. The effect of low illumination and foveal fusion lock on clinical fixation disparity measure­ments with the Sheedy Disparometer. Ophthal. Physiol. Opt. 5: 171-178, 1985. DOI: https://doi.org/10.1111/j.1475-1313.1985.tb00653.x

10. Debsyngh, S., Orzech, P.L. and Sheedy, J.E. Effect of a central fusion stimulus on fixation disparity. Am. J. Optom. Physiol. Opt. 63: 277-280, 1986. DOI: https://doi.org/10.1097/00006324-198604000-00007

11. Pickwell, L.D., Gilchrist, J.M. and Hesler, J. Comparison of associated heterophoria measurements using the Mallett test for near vision and the Sheedy Disparometer. Ophthal. Physiol. Opt. 8: 19-25, 1988. DOI: https://doi.org/10.1111/j.1475-1313.1988.tb01077.x

12. Dowley, D. Fixation disparity. Optometry and Vision Science. 66: 98-105, 1989. DOI: https://doi.org/10.1097/00006324-198902000-00007

13. Mitchell, A.M. and Ellerbrock, V.J. Fixa­tion disparity and the maintenance of fusion in the horizontal meridian. Am. J. Optom. Arch. Am. Acad. Optom. 32: 520-534, 1955. DOI: https://doi.org/10.1097/00006324-195510000-00003

14. Schor, C.M. The relationship between fusional vergence eye movements and fixation disparity. Vision Res. L 9: 1359-1367, l979a. DOI: https://doi.org/10.1016/0042-6989(79)90208-6

15. Rutstein, R.P. and Eskridge, J.B. Clinical evaluation of vertical fixation disparity. Part ill. Adaptation to vertical prism. Am. J. Optom. Physiol. Opt. 62: 585-590, 1985. DOI: https://doi.org/10.1097/00006324-198509000-00002

16. Mitchell, D. A review of the concept of "Panums fusional areas". Am. J. Optom. 43: 387-401, 1966. DOI: https://doi.org/10.1097/00006324-196606000-00004

17. Schor, C. M. The influence of rapid prism adaptation upon fixation disparity. Vision Res. 19: 757-765, 1979. DOI: https://doi.org/10.1016/0042-6989(79)90151-2

18. Yekta, A.A. and Pickwell, L.D. The relationship between heterophoria and fixation disparity. Clinical & Experimen­tal Optometry. 69: 228-231, 1986. DOI: https://doi.org/10.1111/j.1444-0938.1986.tb04597.x

19. Pickwell, L.D., Yekta, A.A., and Jenkins, T. C.A. Effect of reading in low illumina­tion on fixation disparity. Am. J. Optom. Physiol. Opt. 64: 513-518, 1987. DOI: https://doi.org/10.1097/00006324-198707000-00005

20. Yekta, A.A. The clinical significance of fixation disparity in binocular vision. Ph.D. thesis, School of Optometry, University of Bradford, England, 1988.

21. Yekta, A.A., Pickwell, L.D. and Jenkins, T. C.A. Binocular vision, age and symp­toms. Ophthal. Physiol. Opt. 9: 115-120. 1989. DOI: https://doi.org/10.1111/j.1475-1313.1989.tb00829.x

22. Mills, G. Designing a new near muscle balance test. The Optician. February, 24, 115-120, 1950.

23. Jenkins, T.C.A., Pickwell, L.D. and Yekta, A.A. Criteria for decompensation in binocular vision. Ophthal. Physiol. Opt. 9: 121-125, 1989. DOI: https://doi.org/10.1111/j.1475-1313.1989.tb00830.x

Published

2026-06-22

How to Cite

Yekta, A., Pickwell, L., & Jenkins, T. (2026). The Relationship Between the Type and Central Slope of the Fixation Disparity Curve and Symptoms . Canadian Journal of Optometry, 51(4), 163–165. https://doi.org/10.65636/cjo.v51i4.7037

Issue

Section

Original Research