Abstract
Purpose :
To evaluate objectively the change in fusional vergence amplitudes at near in adults with typical binocular vision after performing an office-based vergence/accommodative vision therapy protocol.
Methods :
In this semi-cross-over study, 34 young adults (24±4 years) were randomly classified into an experimental group (EG) (N=16), who did 45min/week of office-based vergence/accommodative vision therapy for 12 weeks; or a control group (CG) (N=16), who did 15min/week of office-based therapy based on eye movements exercises in the frontal plane for 12 weeks. After week 12, the CG did the same vision therapy protocol as the EG. To measure fusional vergence amplitudes objectively, a column of 0.2 logMAR letters was presented to the two eyes in an haploscopic set-up. Disparity increased smoothly at 1PD/s up to 45PD and eye movements were recorded using an Eyelink 1000 Plus (SR Research) at 500Hz. Break points of positive (PFV) and negative fusional vergence (NFV) were determined offline using a custom algorithm to analyze the recorded eye movements. Participants’ PFV and NFV were measured before starting the vision therapy (week 1), and in weeks 6, 12, and 18 and 24 for the CG.
Results :
NFV and PFV break points averaged across participants in each group at each time point are presented in Table 1. Before starting the vision therapy protocols, participants in the two groups exhibited similar PFV and NFV (t(15)=-0.569, p=0.578, and z=-0.454, p=0.650, respectively). PFV break points did not change significantly during the first 12 weeks of vision therapy for the CG nor the EG (F(2,60)=1.104, p=0.338). Similarly, no statistically significant differences in NFV were found for the two groups (F(1.39,41.94)=1.578, p=0.219). The CG exhibited a significant increase in PFV and NFV amplitudes after performing the office-based vergence/accommodative vision therapy protocol (evaluation in week 24) compared to their baseline at week 12 (F(2,30)=7.410, p=0.002 and F(1.16,17.41)=5.202, p=0.031, respectively).
Conclusions :
We observed an improvement in PFV and NFV amplitudes in participants who did 24 weeks of two different vision therapy protocols, but not after the 12 weeks of vergence/accommodative vision therapy protocol done by the EG. These results suggest a potential training effect in the measurement of fusional vergence amplitudes.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.