Can prism adaptation for acquired esotropia be accomplished in a shorter time frame?

Purpose: Results of the Prism Adaptation Study (PAS) indicated that surgica l success rates were highest when augmented surgery was performed for the i ncreased angle of deviation in the prism adaptation responders who underwen t surgery for the prism-determined angle of esotropia. The purpose of this study was to see if the prism adaptation response process could be performe d in a shorter time span than dictated in the PAS protocol (minimum, 4-7 da ys), Methods: After the prescription of appropriate spectacles, patients wi th acquired stable esotropia were prism adapted and then reexamined and rea dapted if necessary at 24 hours and 4 to 7 days. The 4- to 7-day visit was the determining visit in the PAS. The question in this study was whether th e 24-hour visit would provide the same end point and allow adaptation in a shorter period of time. In addition, a motor end point was used in this stu dy, whereas in the PAS, the end point was both motor and sensory. Results: Thirty-two patients met the entry criteria. Nineteen of the 32 patients bui lt up their entry angle during the prism adaptation process. Thirty of the 32 patients who left the office stable at the 24-hour visit remained stable at the 4- to 7-day visit. Conclusion: If the 4- to 7-d ay visit is used as the "gold" standard, 94% of the patients in this study would not have bene fited from a longer (beyond 24 hours) wear time of prisms, With the use of motor stability, prism adaptation can be carried out in a reproducible and timely fashion.