Convergence Excess: Characteristics and Treatment

Abstract

Convergence excess esotropia may result from a high AC/A ratio (accommodative convergence excess), abnormally high proximal convergence (non-accommodative convergence excess), or decreased accommodative amplitudes (hypoaccommodative convergence excess). To distinguish between the three, the gradient AC/A ratio must be calculated, and the accommodative amplitudes measured. Of 77 consecutive patients with a distance-near disparity of ≥ 10^Δ, 51% had a high AC/A ratio (mean 8:1) and normal accommodative amplitudes, 48% had a normal AC/A (mean 3:1) and normal accommodative amplitudes, and 1% had normal AC/A and low accommodative amplitudes. There was no correlation between the magnitude of the distance-near disparity and the AC/A ratio.

Convergence excess secondary to high AC/A ratio initially responded well to bifocals, though most eventually required surgery due to deterioration of the strabismus angle, bifocal intolerance, or inability to wean from the bifocal power. Non-accommodative convergence excess was managed surgically, and hypoaccommodative convergence excess was treated with spectacles.

• convergence excess
• AC/A ratio hypoaccommodation
• esotropia
• surgery
• glasses
• bifocals