Abstract
Purpose:
Rapid serial visual presentation (RSVP) of words one at a time at the same spatial location increases reading speed in people with normal vision and those with central vision loss by minimizing the need to make inter-word eye movements. Additionally, displaying words such that the optimal viewing-position (OVP), a location between the beginning and middle of a word, lies at fixation increases reading speed in individuals with normal vision. It has recently been suggested that a combination of OVP alignment and highlighting the OVP using a different colored letter leads to improved reading speed in normals (Spritz software). Here we examine whether aligning the OVP of words with fixation, and/or highlighting it, can increase RSVP reading speed in patients with central vision loss.
Methods:
We measured reading speed for sentences in six patients with central vision loss due to macular disease (age: 50-85, logMAR acuity: 0.22-1.20). Participants fixated a gap between two vertical bars while words were presented at seven different exposure durations using the method of constant stimuli. Thresholds were determined as the duration that corresponded to 80% of correctly identified words. The effect of different combinations of horizontal spatial position and the highlighting of individual letters (using letter color or contrast polarity) on reading speed for sentences and word identification speed for 7 and 9 letter words were investigated for each patient.<br />
Results:
Word identification speed was not significantly affected by changes in the horizontal spatial position of words or the highlighting of letters. For sentence reading, the mean reading speed when the central letter of words was aligned with fixation (standard RSVP) was 142 words per minute (wpm). When the OVP of words was aligned with fixation, and all letters were the same color, mean reading speed increased to 165 wpm, significantly higher (p = 0.02, Friedman test) than the standard RSVP paradigm. Aligning the OVP at fixation and highlighting the letter at fixation led to a mean reading speed of 124 wpm, which was not statistically different from the reading speed obtained for the standard RSVP condition.
Conclusions:
Aligning the OVP of words with fixation leads to improved reading ability in patients with central vision loss. Highlighting letters at the OVP location provides no benefit to reading speed.