Stereoacuity measurement: Duration of misalignment, not age at alignment, key

MAUI, Hawaii — The duration of misalignment affects the quality of stereoacuity in patients who develop stereopsis in the treatment of congenital esotropia, a study shows.

Malcolm R. Ing, MD, and colleagues compared the Titmus stereoacuity result with the duration of alignment for a group of patients who underwent surgical alignment by 24 months of age.

“The purpose of our comparison was to determine whether the age at alignment or duration of misalignment before surgery affected the stereoacuity result,” said Dr. Ing here at Hawaii 2003: the Royal Hawaiian Eye Meeting. “The present study shows a larger time window for the development of Titmus stereoacuity,” he said during the Special Lecture: Stereo Acuity in Congenital Esotropia.

The age at alignment and duration of misalignment for 90 patients (mean age at follow-up: 9 years, 9 months) was correlated with the percentage of patients with stereopsis and quality of the stereoacuity result as determined by the Titmus vectograph overlay.

Patients aligned after 12 months of age showed a decreased percentage with stereopsis (P < .05, power 0.8). The quality of stereoacuity was decreased for patients with a duration of misalignment longer than 12 months (P = .001, power 0.8).

In the study, 74% of patients demonstrated stereopsis, and the quality of stereoacuity was 51% at zero to 12 months and dropped to 19% at 13 to 21 months. “No patients throughout the study attained stereopsis after 18 months of misalignment,” said Dr. Ing.