Fusional Vergence Measures and Their Significance in Clinical Assessment

Abstract

Purpose: The aims of this study have been to evaluate differences between ranges in eso or exo deviances and with varying target size.

Methods: Evaluation of sensory status in compensated deviations included measures of fusional vergence (blur, break and recovery values) with randomization of target size and order of prism base. Angle of deviation measures were assessed for each case.

Results: Twenty-two subjects, 7 esophoric and 15 exophoric, were recruited. Median prism fusional vergence range at near fixation was 25BO to 10BI (central target); 35BO to 12BI (peripheral target). At distance fixation median range was 16BO to 6BI (central); 25BO to 6BI (peripheral). Esophorics had a range shift towards the base out range. Exophorics had a shift towards the base in range.

Conclusions: Smaller positive fusional vergence values were obtained with small compared with large target sizes. Additionally, esophoric subjects had a trend towards larger base out ranges while exophoric subjects had a trend towards larger base in ranges.

KEYWORDS::

• fusion
• vergence
• strabismus
• eso
• exo

ACKNOWLEDGMENT

Declaration of Interest: No funding was allocated to this paper. The author reports no conflicts of interest. The author alone is responsible for the content and writing of the article.