convergence excess
Convergence excess is an esophoria at near with orthophoria or a low to moderate esophoria at distance, reduced negative fusional vergence and a high AC/A ratio. Convergence excess is one of the most common nonstrabismic binocular vision problems, found in 5.9% of one population of symptomatic patients seeking vision care.1
The AC/A ratio measures the change in convergence for each diopter of accommodation, and the normal value is about 4 prism diopters per diopter. A high ratio, above 6, makes accommodation for near vision produce an excess of convergence, and convergence excess rarely occurs with a low ratio.2 Some authors use a 10 prism diopter difference between distance and near as a guideline. Because a ratio above 7:1 counts as high, a difference of as little as 3 prism diopters can fit the diagnosis.1
Symptoms come with reading and other close work and include eyestrain, headaches, blurred vision, diplopia, sleepiness and loss of comprehension over time.1 A separate entity, nonaccommodative convergence excess esotropia, is an esotropia at least 15 prism diopters larger at near than at distance in a fully corrected patient whose AC/A ratio is normal by the gradient method. Bifocals and miotics have little if any effect on its near deviation, so the excess convergence must arise from a source other than accommodation, perhaps tonic innervation.3
More detail
Some patients with convergence excess have no symptoms, possibly because of suppression, avoidance of near tasks, a high pain threshold or closing one eye to read.1 Prevalence reached 8.2% in a prospective study of 1,650 children aged 6 to 18 years and 1.5% in a university population.1
Nonaccommodative convergence excess esotropia usually begins between 2 and 3 years of age, with orthotropia or a small esotropia at distance and an esotropia of 20 to 40 prism diopters at near.3 Estimating the AC/A ratio by comparing the distance and near deviations can miss this diagnosis and lead to bifocals that the patient will not respond to.3
Sources (6)
- Scheiman and Wick, Clinical Management of Binocular Vision, ch. 10
- Pickwell's Binocular Vision Anomalies, ch. 7
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 16
- Rouse, M. W., Borsting, E. J., Mitchell, G. L., Scheiman, M., Barnhardt, C., Berman, E., ... & Kulp, M. T. (2004). Accommodative and vergence dysfunction. Optometric Clinical Practice Guidelines, 1-57. https://www.aoa.org/AOA/Documents/Practice%20Management/Clinical%20Guidelines/Consensus-based%20guidelines/Care%20of%20Patient%20with%20Accommodative%20and%20Vergence%20Dysfunction.pdf
- Cacho-Martínez, P., García-Muñoz, Á., & Ruiz-Cantero, M. T. (2016). Extraocular Muscles Tension, Tonus, and Proprioception in Infantile Strabismus: Role of the Oculomotor System. BioMed Research International, 2016, 1-11. https://doi.org/10.1155/2016/6965658
- Arnoldi, K. A. (1999). Convergence excess: characteristics and treatment. American Orthoptic Journal, 49, 37-47.
Reviewed October 2026