A Strategy for Averaged Estimates of Visual Field Threshold

Abstract

Purpose: The purpose of this work is to design a rapid perimetric strategy to provide averaged results. Methods: We designed a simulation examination model using the distribution frequency of local deviations or defects, based on a retrospective study of 90,335 examinations performed in a glaucoma department. Results: Threshold deviation from normal age-adjusted values of 6 points representative of the main areas of glaucomatous visual field allowed estimating the real mean deviation (MD) with a correlation coefficient r=0.995 (SE=0.71 dB) when original values were used, and r=0.984 (SE=1.26 dB) when values from a rapid simulated test model were used. SE of the local deviations (average=3.06 dB) was close to usual mean threshold fluctuation in patients with different degrees of defect. In patients with early glaucoma (MD<6 dB) the SE of the estimated MD was <0.9 dB and the SE in estimating the local point-to-point deviations was 1.8 dB. We included 3 additional phases to obtain 3 additional results and a final averaged result. For the average and median of the 4 phases, the SE of MD ranged from 0.4 to 0.5 dB for the whole sample and from 0.3 to 0.4 in early glaucoma. Local deviation SE was close to 2 dB in the whole sample and between 1.2 and 1.5 dB in early glaucoma. Conclusions: Bearing in mind threshold fluctuation, the strategy allows for several possible outcomes, and provides averaged and theoretically more stable results.