En col·laboració amb la Universitat Autònoma de Barcelona (UAB), la Universitat de Barcelona (UB) i l’Institut de Ciències Fotòniques (ICFO)

This study was designed to investigate if the velocity of the stimulus used during the near point of convergence (NPC) exam affected the performance of the vergence system. The effects of target’s distance and ocular dominancy were also analyzed. 14 patients with a mean ± SD age of 26.3 ± 4.6 years participated in the study. The target used to measure the NPC was moved at three different velocities (20, 35 and 50 mm/s) along a motorized rail while the eye movements of the patient were registered with an eye-tracker. The vergence error was analyzed considering the overall range of target’s distances, and the initial and final periods. The mean ± SD vergence error obtained for the total range are: 1.05º ± 0.82º (20 mm/s), 1.13º ± 0.84º (35 mm/s) and 1.24º ± 0.89º (50 mm/s). The results obtained considering the near range of distances are: 3.04º ± 1.81º (20 mm/s), 3.14º ± 1.91º (35 mm/s) and 3.36º ± 1.95º (50 mm/s). Finally, the vergence error considering the initial part of the movement are: 0.49º ± 0.15º (20 mm/s), 0.48º ± 0.13º (35 mm/s) and 0.50º ± 0.14º (50 mm/s). There are not significant differences in vergence error with the different velocities. However, the vergence error is significantly greater when more convergence is needed. Although there is no significant effect of ocular dominancy on vergence error there is a trend demonstrating that the greater the interocular difference in vergence error, the more likely the most accurate eye agreed with the dominant eye.