Intermittent exotropia with high AC/A ratio: is it a bane to surgical cure? Some facts and fictions of the two clinical tests: occlusion of one eye and the use of +3.00 spherical lenses.

BACKGROUND AND PURPOSE

To review the multiple factors in intermittent exotropia (X(T)) responsible for the discrepancy between the distance and near deviations; to challenge the classification of X(T) into types according to the two standard clinical tests of occlusion of one eye and the use of +3.00 D spherical lenses at near by demonstrating the pitfalls of these two tests, as in X(T), masquerading as high AC/A ratio at times or as strong proximal fusional convergence at other times.

METHODS OF STUDY

Fifteen patients demonstrating findings characteristic of X(T) with so-called high AC/A ratio are reported. Fourteen patients had an exodeviation initially. The fifteenth had become exotropic following medial rectus recessions for infantile esotropia. Fourteen patients had bilateral lateral rectus recession and one had unilateral lateral rectus recession.

RESULTS

The only patient who did develop a long term postoperative overcorrected high AC/A ratio esotropia was the patient who had initially an infantile esotropia. Of the other 14 patients initially X(T) none developed a long term postoperative overcorrected high AC/A ratio esotropia. Fifty % of these were "cured" (OT +/- 8 delta) and 50% had a "significant (> or = 8 delta) recurrence" of their exodeviation.

CONCLUSION

Patients with intermittent exotropia and significantly more exodeviation at distance than at near, and classified to have high AC/A ratio by occlusion of one eye and the use of +3.00 spheres at near, do not necessarily have a high accommodation-convergence relationship but rather, other factors mimicking this high AC/A relationship. They do not necessarily develop a postoperative overcorrected high AC/A ratio esotropia.