# Innovative Binocular Vision Testing for Phoria and Vergence Ranges Using Automatic Dual Rotational Risley Prisms

## TL;DR

This study tested a new device for measuring binocular vision and found it to be highly correlated with traditional methods, though not fully interchangeable.

## Contribution

The study introduces and validates the use of automatic dual rotational Risley prisms for binocular vision testing.

## Key findings

- ADRRPs showed strong correlations with traditional methods for measuring phoria and vergence ranges.
- Bland–Altman analysis revealed systematic bias and limits of agreement, indicating the methods are not fully interchangeable.
- ADRRPs show potential for clinical use but require further validation.

## Abstract

This study evaluated binocular visual function using automatic dual rotational Risley prisms (ADRRPs) to measure phoria and vergence ranges. Thirty-nine (mean age: 21.82 ± 1.10 years; age range: 20–24 years) healthy adults with normal binocular vision participated. Each underwent baseline refraction exams followed by phoria and vergence tests conducted using both a phoropter with Maddox rods and the ADRRPs. The results revealed a strong positive correlation between the two instruments for distance phoria (r = 0.959, p < 0.001) and near-phoria measurements (r = 0.968, p < 0.001). For vergence testing, positive fusional vergence (PFV) at distance showed a moderate-to-strong correlation for break points (r = 0.758, p < 0.001) and a moderate correlation for recovery points (r = 0.452, p < 0.001). Negative fusional vergence (NFV) at distance demonstrated a strong correlation for break points (r = 0.863, p < 0.001) and a moderate correlation for recovery points (r = 0.458, p < 0.01). Near-vergence testing showed moderate-to-strong correlations for break points (r = 0.777, p < 0.001) and recovery points (r = 0.623, p < 0.001). The inclusion of Bland–Altman analysis provides a more comprehensive evaluation of agreement between ADRRPs and the phoropter. While strong correlations were observed, systematic bias and LoA indicate that these methods are not perfectly interchangeable. The ADRRPs demonstrated potential for binocular vision assessment but require further validation for clinical application.