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Yuka Aoyama, Hiroshi Murata, Mayumi Tahara, Mieko Yanagisawa, Chihiro Mayama, Ryo Asaoka; A method to identify the edge of visual field scotoma; the estimation of prediction error of the visual field sensitivity is large at the steep ‘edge’ of scotoma. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3914.
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© ARVO (1962-2015); The Authors (2016-present)
Humphrey 24-2 visual field (VF) test grid has a spatial gap, since each test point is located six degrees apart. The purpose of this study was to create a method to identify the edge of VF scotoma and to investigate the relationship between the steepness of the ‘edge’ of scotoma and the prediction error of VF sensitivity.
Eleven clinically stable glaucomatous patients with reliable VFs were recruited. Then, using the latest VFs (Humphrey 24-2) of these patients, the gradient of the plane on the hill of vision from the sensitivity of adjacent four/three points is calculated, so that the ‘edge’ of VF damage is identified. Next, VF measurement was carried out, adding ten test points at the centre of adjacent four/three points (red circle, Figure 1) where the gradient of the plane is largest (Full threshold, Custom mode). The VF measurements were performed using two approaches; random target presentation of 62 test points together and showing ten added points following or prior (randomly selected) to 52 (24-2) points. Each measurement with each approach was repeated twice (in total four measurement for a patient) in a same visit. Then, the absolute value of the difference between the measured sensitivity of the added ten test points and the average of the sensitivities of surrounding three/four test points were calculated. Finally, the relationship between the gradient of sensitivity plane and the absolute difference was investigated using the multiple level modeling (MLM).
MLM revealed significant relationship between the absolute difference and the gradient of plane with all of the four measurements (p<0.05).
The discrepancy between the estimated sensitivity from the surrounding test points and the actually measured sensitivity at the gap in the 24-2 grid became large where the edge of scotoma is steep. It may be advantageous to increase the spatial information by carrying out additional measurement at these areas, in order to estimate scotoma more accurately.
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