Influence of test reliability on the screening performance of frequency-doubling perimetry.
OBJECTIVE
To investigate the influence of test reliability on the screening performance of frequency-doubling perimetry (FDT).


METHODS
Cross-sectional study.


METHODS
FDT sensitivity and specificity were calculated three times using three different strategies for handling unreliable (that is, >0 reliability indices outside normal limits) and unfeasible (that is, could not be completed) tests in 452 glaucoma patients from our outpatient department and 237 healthy subjects recruited outside the hospital.


RESULTS
Unreliable (P = .01) and unfeasible (P < .001) tests occurred more frequently in glaucoma patients when compared with healthy subjects. Best screening performance was obtained by interpreting unreliable tests as if they were reliable and considering unfeasible tests as positive. With this strategy, sensitivity was 0.90 (95% confidence interval 0.87-0.93) and specificity 0.81 (95% confidence interval 0.76-0.86).


CONCLUSIONS
Unreliable and unfeasible FDT tests appear to contain useful information.
Heeg
Govert P
GP
Department of Ophthalmology, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands.
Jansonius
Nomdo M
NM
D003430:Cross-Sectional Studies; D005189:False Positive Reactions; D005500:Follow-Up Studies; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015351:Vision Screening / Q000592:standards*; D058609:Visual Field Tests / Q000592:standards*; D014794:Visual Fields