Assessing the True Amount of the Deviation: Measuring Patients to Neutralization or to Reversal

Abstract

Objective:

Measurement of a deviation with the alternate cover test is a routine part of the orthoptic examination. This study was conducted to determine if there was a significant (>4^Δ) difference between measuring the deviation to no movement (Neutralization I) or return to no movement after reversal (Neutralization II).

Methods:

A prospective study of 33 patients at The New York Eye & Ear Infirmary Orthoptic Department.

Results:

No significant difference was seen between Neutralization I and Neutralization II in all but three patients, all of whom had esotropia of 20^Δ or less.

Conclusions:

Measuring to no movement (Neutralization I) seems to produce the same amount of deviation as measuring to reversal and back to neutralization (Neutralization II) in 95% of the measurements done. There is a small group of patients where the Neutralization II measurement was larger than the Neutralization I measurement by 6^Δ. All three patients in this group were esotropic with small angles of esotropia, 20^Δ or less.

• prism and cover test
• neutralization