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Related Experiment Videos

Adaptive disorders of accommodation and vergence in binocular dysfunction.

C Schor1, D Horner

  • 1University of California, School of Optometry, Berkeley 94720.

Ophthalmic & Physiological Optics : the Journal of the British College of Ophthalmic Opticians (Optometrists)
|July 1, 1989
PubMed
Summary

Binocular vision disorders like convergence excess and insufficiency may stem from issues with how the eyes adapt. This study found differences in accommodative and vergence adaptation between these groups, suggesting adaptive disorders underlie these conditions.

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Area of Science:

  • Ophthalmology
  • Neuroscience
  • Vision Science

Background:

  • Binocular vision disorders are clinically classified using the Duane-White system based on the accommodative-convergence ratio (AC/A).
  • Convergence excess and insufficiency are traditionally linked to high and low AC/A ratios, respectively.
  • Recent research suggests AC/A ratio is influenced by tonic accommodation and vergence adaptability.

Purpose of the Study:

  • To investigate if clinical categories of convergence excess and insufficiency correlate with specific patterns of tonic accommodation and vergence adaptation.
  • To determine if adaptive disorders of accommodation and vergence underlie common binocular vision problems.

Main Methods:

  • Compared accommodative after-effects (lens adaptation) and vergence after-effects (prism adaptation) between patients diagnosed with convergence excess and convergence insufficiency.

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  • Analyzed the amplitude and duration of adaptive responses in each group.

    • Main Results:

    • Patients with convergence insufficiency exhibited greater amplitude and duration of accommodative after-effects compared to the convergence excess group.
    • The convergence excess group showed a reverse trend in vergence after-effects compared to the convergence insufficiency group.
    • Significant differences in adaptation capabilities were observed between the two clinical groups.

    Conclusions:

    • The findings suggest that adaptive disorders of accommodation and vergence are associated with clinical classifications of convergence excess and insufficiency.
    • These adaptive deficits may represent the underlying mechanism for these binocular vision disturbances.
    • This challenges the traditional view of AC/A ratio as an independent variable, highlighting the role of adaptation.