Description about ocular movements- Vergence and versions

1. Vergence & Version
Optom.Monika Pallan

2. Vergence
• Versions are the movements that cause the eye to change the
directions from right to left,with no change in the distance of
fixated object.
• Both the eyes rotate through an equal angle to right or left,
hence known as conjunctive eye movements.
• Also known as conjugate eye movements.
• Refers,to the movement of eyes in the same direction.

3. Vergence
• In vergence movements, the visual direction remains unchanged,
but distance to the fixation point changes.
• The eyes rotate in opposite directions; both may rotate inward
(convergence) or outward (divergence).
• These are called disjunctive movements.
• Refers to movements of the eyes in opposite directions.

4. • Convergence
• Divergence
• Supravergence
• Infravergence
• Measured in Prism Dioptres (Δ).
• Formula for convergence :
• Convergence : displacement (cm) X 1/test distance (m)

5. • Accommodation is measured to the spectacle plane whereas
convergence is measured at the eyes centre of rotation (COR).
• COR is assumed to be 27mm behind spectacle plane.

6. Stimulus for vergence
• Changes in accommodation referred to as accommodative
convergence
•
• Retinal Disparity referred to as fusional convergence
• Awareness of closeness of an object referred to as proximal
convergence

7. Types of convergence
• 1. Tonic: the stimulus to fusion is removed (phoria position), eyes are
at a position of rest.
• 2. Proximal: voluntary, awareness of near objects, psychic
convergence.
• 3. Accommodative: induced by the exercise of accommodation.
• 4. Fusional: avoids diplopia; stimulus is retinal disparity.

8. AC/A ratio
• The AC/A Ratio is the ratio of the accommodative convergence (AC)
in ∆ to the stimulus to accommodation, (A) in dioptres.
• At 6m, an emmetrope has approximately 0 D stimulus to
accommodate.
• At 40cm, the accommodative stimulus is 2.50D

9. High AC/A ratio
• Anomalies where binocular vision is maintained but often with
significant degrees of eyestrain (asthenopia):
• Heterophorias
• Anomalies of fusional vergence
• Fixation disparity
• Anomalies of accommodation

10. • Anomalies where binocular vision is absent:
• Heterotropias
• Heterotropia may be accompanied by one or more adaptive
phenomena including suppression, amblyopia, ARC and eccentric
fixation.