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Johan J. Pel, Koen A. Vermeer, Michel C. van Beijsterveld, Hans G. Lemij, Johannes van der Steen; Correlation Between Reduced Visual Field Sensitivity And Saccadic Reaction Times. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4812.
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© ARVO (1962-2015); The Authors (2016-present)
In current functional visual field (VF) tests, a subject needs to suppress reflexive eye movements to visual stimuli. We developed an eye movement perimeter (EMP), in which automatically tracked eye movements confirm the detection of visual stimuli. This approach enables the assessment of a saccadic reaction time (SRT) to a detected visual stimulus. The aim of the present study was to assess the correlation between SRT-values in eyes with glaucomatous visual fields.
We included 41 subjects who were glaucoma suspects without visual field defects and glaucoma patients with frank visual field defects (median age 62 years (range 52-69 years; 25th-75th percentile)). Each subject underwent a 24-2 HFA test (Carl Zeiss Meditec, Jena, Germany; standard white-on-white, SITA fast). Eyes were classified as perimetrically affected if the Mean Deviation (MD) was below 0 dB. Next, each subject underwent an EMP measurement in which we used the same stimulus grid. Visual stimuli (100% brightness on 60% brightness background) were presented on an eye tracker’s monitor (T60XL, Tobii, Sweden). Vision of the untested eye was blocked by a PMMA shield, still allowing gaze tracking of both eyes. Subjects were asked to fixate a central stimulus (visible throughout the test). Next, peripheral stimuli were shown one-by-one for a fixed duration of 1.2 s preceded by random fore-periods of 1.5-2.5 s. To assess the correlation between VF sensitivity and SRT, the SRT measurements of the affected eyes were first corrected for location dependence by subtracting the average location-matched SRT measured in the normal eyes. Next, Spearman's rank correlation between VF sensitivity (dB) and SRT (ms) was calculated for each stimulus location in the affected eyes.
In total, 52 eyes were included; 37 affected eyes (MD of -4.6dB (range -10.3 till -1.6 dB)) and 15 normal eyes (MD of 0.8 (range 0.4 till 1.3)). In the affected eyes, the median SRT-values were 467 ms (range 366 till 583 ms) and in the normal eyes, these values were 383 ms (range 317 till 466 ms). A highly significant correlation was found between affected VF sensitivity and the SRT-values (Rho = -0.35; p<0.001).
The results suggest that SRT values become prolonged in reduced VF sensitive areas. Future studies need to address the repeatability of EMP, its learning effect and the effect of stimulus-intensity dependence on SRT-values. We conclude that this study demonstrates the feasibility to use eye movement perimetry as a tool to measure VF responsiveness.
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