This document discusses different types of convergence in the eyes. It defines accommodative convergence as convergence that occurs during accommodation or when the eyes receive an impulse to accommodate. The near reflex triad is defined as the reflex of the eyes to focus on a near object, consisting of accommodation, convergence, and miosis. It also discusses the AC/A ratio, which is a measurement of accommodative convergence, and how abnormalities in this ratio can cause different types of strabismus. Proximal convergence is induced by the proximity of an object rather than its optical properties, and has an inverse relationship with changes in fixation distance.

1. ACCOMMODATIVE AND
PROXIMAL
CONVERGENCE
DR. USAMA

2. ACCOMMODATIVE CONVERGENCE:
• It is the convergence that occurs when eyes accommodate
or when a nerve impulse to accommodate is discharged to
the eyes.
• Stimulus:
• Blurred retinal images

4. NEAR REFLEX TRIAD:
• What is the near reflex triad?
• The near reflex is the action of the eye for adjustment to
fixate on a near object. The reflex is a triad which consists
of accommodation, convergence and miosis. Spasm of the
near reflex (SNR) is when this triad persists when the
patient is not fixating on a near object.

5. AC/A RATIO:
• Accommodative convergence is measured in prism
diopters.
• Myopes have high AC/A ratio.
• Hypermetropes have low AC/A ratio.
• Pupillary distance must also be considered in determining
the AC/A ratio.

6. ABNORMALITIES OF AC/A RATIO:
• High AC/A ratio cause excessive convergence and
produces convergent squint (esotropia).
• Low AC/A ratio cause divergent squint (exotropia).

7. PROXIMAL CONVERGENCE:
• It is induced by the proximity of the object of regardor the
awareness of proximity of near object.
Example:
• Haploscope optically set at infinity, proximal convergence
is used.

9. INVERSE RELATIONSHIP:
• Proximal convergence ×1/ change in fixation distance
• Change in fixation distance is expressed as change in
vergence of light i.e in diopters.
• Each diopter of change of fixation distance ,an
approximate change of 1.5∆ occurs in proximal
convergence.