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The correlation of Brock String response, fixation disparity, and anticipation timing

1 May 2005


Background: This study investigated the relationship between ocular alignment measurements taken from the standard distance Brock String and the Mentor 0&0 B-VAT II. Also studied was the possible relationship between ocular alignment and the anticipation of a dynamic event as measured by the Bassin Anticipation Timer.

Methods: 71 subjects performed a standard distance Brock String test. The subjects were asked whether they perceived the bead within a fused area of string, and if so, the subject was asked to identify the portion of the fused area where the bead appeared. The subjects' fixation disparity was also used to determine if there is a correlation with anticipation timing as measured by the Bassin Anticipation Timer.

Results: 47 of 71 subjects (66%) perceived fused sections of the distance Brock String. Of these 47 subjects, 38 (81%) stated the bead was in the front 113 of the fused section. 6 (13%) subjects said the bead was in the middle 1/3 of the fused portion. The remaining 3 (6%) subjects reported the bead to appear in the rear 113 of the fused area. BVAT analysis claimed 29 (41%) subjects had a mean exo di sparity, while 17 (24%) subjects had a mean fixation disparity of ortho, and the remaining 25 (35%) subjects had mean eso fixation disparities. Correlations between fixation disparity and anticipation timing were found to be quite low.

Conclusions: Statistical comparisons made between distance Brock String and By AT fixation disparity performances did not yield the significant results necessary to conclude that distance Brock String responses accurately represent any one fixation disparity category ( eso, exo, or ortho ). In addition, no statistically significant relationship was determined between distance Brock String orB-VAT fixation disparities and any of the Bassin Anticipation Timer data


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