Effects of Wearing a Swimming Cap and Goggles on Phoria and Fusional Vergence

This study evaluated changes in phoria and negative (NFV) and positive fusional vergence (PFV) when wearing a cap and/or goggles. Thirty-five healthy university students aged 20–25 years participated in the study. All participants were examined for phoria, NFV, and PFV at distance and near. A rotary prism was used before and after wearing a cap, goggles, and both a cap and goggles. The frequency of overall average change in phoria, NFV, and PFV after wearing swimming equipment compared with non-wearing ranged from one-third to four-fifths. The order of frequency in change was wearing of goggles and a cap, goggles alone, and a cap alone. The frequency of a prism prescription, determined by the relationship between phoria and vergence, was similar or higher for wearing than for non-wearing and higher at near than at distance. The effect on change in phoria and fusional vergence was greater when wearing both a cap and goggles than when wearing either alone. These findings demonstrate that wearing both swimming cap and goggles that contact or attach around the eyes influence phoria and fusional vergence by inducing pressure or pulling. These changes may contribute to the discomfort associated with the wearing of swimming equipment.