In a 3-year-old child with constant left esotropia of 30 prism diopters and no refractive error, the Prism Adaptation Test (PAT) is performed before surgery. A child who shows full adaptation (manifest angle increases to 50 PD) benefits from surgery targeting the adapted angle because:

• A The original 30 PD represents only the motor component; full 50 PD includes the sensory component
• B Adaptation indicates the child will develop anomalous retinal correspondence
• C Surgery on the larger angle prevents consecutive exotropia
• D Adapters have more stable motor alignment post-operatively ✓

Explanation

The Prism Adaptation Test (PAT) identifies patients who are 'prism responders' (angle increases with prism wear) — operating on the adapted (larger) angle gives better post-operative alignment stability because the surgical target is the true full angle of deviation. Adapters who have surgery on the original smaller angle tend to drift back toward the adapted angle post-operatively (residual esotropia). The PAT is used to optimize surgical dosing in esotropia. The increase in angle with prism is a motor adaptation phenomenon, not a sensory one. This approach is supported by Buckley et al. and used in non-accommodative esotropia management.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.