Short term modification of vergence ramp eye movements in the convergent direction

Prior oculomotor studies have investigated the various effects of short-term modification on vergence, saccadic and smooth pursuit eye movements. Previous vergence studies have concentrated on step modification stimuli. Few have investigated the effects of short-term modification on vergence ramp movements. Thus, this study explores the trends observed within a short-term modification experiment studying smoothly tracking vergence eye movements responses elicited from convergent ramp stimuli. A short-term modification experiment is composed of three phases: baseline, modification and recovery. Baseline and recovery phases contain only test stimuli; whereas, during modification, the subject is presented test and conditioning stimuli in a ratio of 1:5 test to conditioning. The test stimulus is a 0.5 deg/sec vergence ramp presented from a 3 deg vergence angle to a 5 deg vergence angle. The conditioning stimulus is a 2 deg/sec ramp presented over the same visual range. The root mean square error (RMSE) is calculated on all slower (0.5 deg/ sec) ramp responses and compared over the three phases. A significant statistical change is observed between the three stages on day one, but not on day two. A trend that can be attributed to motor memory. This study additionally explores for potential differences between the left and right eye movements. No statistical significant difference of the RMSE is observed between the left and right eye movements. Data supports that the preprogrammed portion of vergence is significantly influenced by the short-term modification experiment described here