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Jaume Pujol, Rosa Borras, Irene Claramunt, Mireia Sanchez, Alfonso Sanchez-Magan, Juan Carlos Ondategui Parra; Objective horizontal heterophoria measurements usinga new vision analyzer. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3894.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the results of two subjective methods commonly used in clinics to measure horizontal heterophoria with an objective method implemented in a prototype of a new fully autonomous and automated vision analyzer (Eye and Vision Analyzer, EVA, DAVALOR, Spain), that records eye movements while the patient watches a true-3D short video game
Measurements were performed in a group of 54 young healthy subjects. Monocular visual acuity at far and near distances equal or better than 0.0 logMAR was required. Subjective methods consisted of Von Graefe with a line of letters (VGL) and the Modified Thorington (MT) test. VGL was performed at 40 cm with an increment speed of prismatic diopters (PD) of 2PD/sec and under controlled conditions of ilumination (L≈450 lux). MT was performed at 40 cm with a RAF ruler and spotlight under controlled conditions of ilumination (L≈50 lux). Moreover, accurate instructions about stimulus alignment were given to the patients. Three measurements were performed for each method with an interval of 5 seconds between them. Objective measurements were made using an Alternant Cover Test procedure (OACT) showing the video game only in one eye during 2 seconds and recording the ocular movements. This procedure was also repeated three times. Runtime, including time for instructions, was also measured
The mean age of the sample was 21.5±1.5 years (range:19 to 24). The mean horizontal heterophoria values were -6.7±6.0 PD for VGL, -1.0±3.8 PD for MT and -2.0±3.0 PD for OACT. The mean value of differences was -5,6±5,3 PD for VGL vs MT, -4,6±4,6 PD for VGL vs OACT and 0,9±2,8 PD for MT vs OACT. The 95% confidence interval (Bland & Altman plot) was 10,48 for VGL vs MT; 9.83 for VGL vs OACT and 2.52 for TM vs OACT. The Intraclass Coefficient Correlation (ICC) was 61,2% for MT vs OACT; 61.9% for VGL vs OACT and 80.4% for TM vs OACT. The runtime was 137±20 sec for VGL;, 83±13 sec. for MT and 26±5 sec. for OACT
The EVA prototype is a useful device to objectively measure horizontal heterophoria using an Alternating Cover Test procedure. Results show a good ICC (>80%) when OACT is compared with MT. Differences between both methods (1PD) are not clinically significant and are within a good confidence interval. VGL shows higher differences and lower ICC when it is compared with OACT and MT. In addition, OACT is more than 3 times faster than MT and more than 5 times faster than VGL
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