In Congenital Nystagmats,Reading Text with Rapid Serial Visual Presentation (RSVP) Reduces Mean Eye Velocity

Most low-vision subjects read text faster from an RSVP display than they do with full PAGE reading. This result has been confirmed with a group of subjects with congenital nystagmus (Plass and Yager, 1995, paper presented at ARVO). The present experiment was intended to determine whether reading with RSVP also reduced the severity of the nystagmus, which may have contributed to the faster reading rates.

Eye position and velocity of congenital nystagmats were recorded with an infrared reflection technique, sampled at 40 s⁻¹. Recordings were made in three conditions: (1) passively viewing a blank computer monitor; (2) silently reading full PAGE text at a size of approximately four times Snellen acuity; (3) silently reading RSVP text at the same size, at about 200 words min⁻¹. We found that: (1) in frequency histograms of instantaneous eye velocities at 25 ms intervals, the full width at half height was an average of 60% smaller for RSVP reading compared to PAGE; (2) with a window of ±5 to 20 deg s⁻¹, depending on the subject's baseline eye velocity, the number of epochs that were at least 75 ms in length, and the total time in these epochs, were significantly greater during RSVP reading than during PAGE reading or viewing a blank screen. We conclude that reading with RSVP reduces nystagmus, and may contribute to greater reading speed.