Accommodation in intermittent exotropia

Purpose Accommodative convergence is often reported to be associated with the control of intermittent exotropia. This paper summarises our published studies on accommodation and convergence responses in distance exotropia. Methods. 19 children with clinically diagnosed distance exotropia were tested in detail using a remote haploscopic photorefractor which measured objective, simultaneous and continuous accommodation and convergence to a range of targets moving in depth, which contained different combinations of the three main cues to near responses (binocular disparity, blur and proximity/looming). We were able to study these children while controlling, during, and after decompensation to exotropia. Results Clinical classifications were rarely borne out by objective findings. Accommodation frequently relaxed dramatically on decompensation. Many strands of evidence suggest that convergence is the main drive to control of the deviation in all cases. Conclusion Convergence is the primary mechanism for the control of all the intermittent exotropias we tested. This was sometimes associated with secondary additional accommodation. Many clinical findings, such as a “high AC/A ratio”, reported symptoms, and response to common therapies can be explained by better by understanding the convergence to accommodation (CA/C) linkages in these patient