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Comparison between Tendency-Oriented Perimetry (TOP) and octopus threshold perimetry
J Morales1, M L Weitzman, M González de la Rosa
1Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock 79430, USA. eyejm@ttuhsc.edu
Objective:
To compare the results obtained by a new ultra-short automated perimetry test known as Tendency-Oriented Perimetry (TOP), which is an algorithm based on estimation of thresholds from information gathered from adjacent points with those obtained by a standard bracketing approach. TOP is designed to save up to 1/5 of the time taken by standard strategy by presenting each stimulus once on each location (instead of 4 to 6 times per location with the standard technique) and reaching a final threshold estimate by gathering information from responses to adjacent locations.
Design:
Prospective, multicenter, observational comparative case series.
Participants/Methods:
Four academic institutions provided data from testing 57 subjects, 15 with a normal ocular exam and 42 with a variety of visual field abnormalities. A total of 228 visual fields were analyzed. Two examinations of standard thresholding testing (Octopus program 32) and two examinations of the TOP program were obtained in each subject the same day.
Main Outcome Measures:
Comparison of global indices such as mean deviation (MD), square root of loss of variance (sLV), topographical defects, point by point differences, reproducibility, sensitivity/specificity, and time required to complete the test.
Results:
Correlation coefficient of global indices between both tests was high, with mean deviation of r = 0.97 (SE[YX] +/- 1.65 decibels) and square root of loss variance of r = 0.93 (SE[YX] +/- 1.10 dB). Mean sensitivity tended to be 1 dB higher while MD tended to be 1 dB lower with TOP strategy. Reproducibility was equally good between both tests for threshold determination as well as for all global indices (MS, MD per quadrant, and LV). Cluster criteria for abnormality demonstrated TOP versus 32: sensitivity of 89/87; specificity of 90/77; positive predictive value of 96/91; negative predictive value of 75/68; and accuracy of 89/84. Mean time taken by this beta version of TOP was 4.05 minutes standard deviation +/- 0.55 versus the standard 32 version taking 14.65 minutes standard deviation +/- 3.75.
Conclusions:
TOP was four times faster than the traditional full-threshold technique and was successful in detecting visual field abnormalities. Defects with TOP tended to be smaller, shallower, and with softer edges than with standard approach. TOP could prove an alternative to traditional perimetric techniques.