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Andrew J Tatham, Ian Murray, Antonios Perperidis, Lorraine Cameron, Alice McTrusty, Harry Brash, Brian Fleck, Robert Minns; Threshold visual field assessment using eye-tracking perimetry compared to standard automated perimetry in glaucoma.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4742.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate a new eye-tracking perimeter for threshold visual field assessment in glaucoma, the Saccadic Vector Optokinetic Perimeter (SVOP), and compare results to standard automated perimetry (SAP).
A cross-sectional study including 36 patients (70 eyes) with glaucoma and 27 controls (54 eyes) recruited at University of Edinburgh, Scotland. All subjects performed SAP and threshold SVOP, with the order randomized. SVOP consists of a computer, display screen and eye tracker, which assesses gaze responses to stimuli presented on the screen. Unlike SAP, the patient is not required to press a response button. Instead a computer algorithm was developed to determine if stimuli are perceived based on direction and amplitude of the gaze response. The test pattern used was equivalent to SAP 24-2 and stimuli were presented at Goldmann size III. The size and position of the stimuli were automatically adjusted to compensate for changes in patient’s position during testing meaning there was no requirement for a chin rest. Stimuli luminance levels corresponded to 14-40 dB. Average and point-wise sensitivity values obtained from both tests were compared using Pearson's correlation coefficient.
Of 124 test pairs, 5 were excluded due to poor quality eye tracking and 10 due to poor reliability or artifact on SAP leaving 109 test pairs for analysis. There was excellent agreement between mean threshold values obtained using SVOP and SAP (r = 0.95, P<0.001) (Figure 1). Excluding the blind spot, correlation between SVOP and SAP individual test point sensitivity ranged from 0.61 to 0.90, with 48 of 54 test points > 0.70. Overall SVOP showed good repeatability with a Pearson correlation of 0.88. The repeatability on a point-by-point basis ranged from 0.66 to 0.98, with 45 of 54 points (83.3%) > 0.80. Repeatability of SAP was 0.87 ranging from 0.69 to 0.96, with 47 of 54 (87.0%) points > 0.80.
We have demonstrated an alternative method of measuring threshold visual fields that is repeatable and compares well with SAP. The technique has advantages over SAP as it does not require the patient to maintain fixation on a single spot, to keep their chin on a rest, or press a button to register a response. Eye-tracking perimetry could have utility for evaluating glaucoma, particularly in patients who struggle with conventional automated perimetry.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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