Improving the prediction of visual field progression in glaucoma using spatial processing.
OBJECTIVE
The authors show how the predictive performance of a method for determining glaucomatous progression in a series of visual fields can be improved by first subjecting the data to a spatial processing technique.


METHODS
Thirty patients with normal-tension glaucoma, each with at least ten Humphrey fields and 3.5 years of follow-up, were included. A linear regression model of sensitivity against time of follow-up determined rates of change at individual test locations over the first five fields (mean follow-up 1.46 years; standard deviation = 0.08) in each field series. Predictions of sensitivity at each location of the field nearest to 1 and 2 years after the fifth field were generated using these rates of change. Predictive performance was evaluated by the difference between the predicted and measured sensitivity values. The analysis was repeated using the same field data subjected to a spatial filtering technique used in image processing.


RESULTS
Using linear modeling of the unprocessed field series, at 1 year after the fifth field, 72% of all predicted values were within +/- 5 dB of the corresponding measured threshold. This prediction precision improved to 83% using the processed data. At the 2-year follow-up field, the predictive performance improved from 56% to 73% with respect to the +/- 5 dB criterion.


CONCLUSIONS
Predictions of visual field progression using a pointwise linear model can be improved by spatial processing without increased cost or patient time. These methods have clinical potential for accurately detecting and forecasting visual field deterioration in the follow-up of glaucoma.
Crabb
D P
DP
Department of Visual Science, Institute of Ophthalmology, UCL, London, United Kingdom.
Fitzke
F W
FW
McNaught
A I
AI
Edgar
D F
DF
Hitchings
R A
RA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D018450:Disease Progression; D005901:Glaucoma / Q000503:physiopathology*; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014786:Vision Disorders / Q000503:physiopathology*; D058609:Visual Field Tests / Q000706:statistics & numerical data; D014794:Visual Fields / Q000502:physiology*