Abstract
Purpose: :
Many combinations of abnormality have been proposed for defining progression using the glaucoma change probability (GCP) method. We tested a series of criteria varying the number of abnormal test locations from 2-8 and the number of visits where the abnormality was confirmed to determine which combination had the optimum sensitivity and specificity.
Methods: :
Sixty (60) normal subjects and 120 glaucoma patients were tested every six months for 4 years with SITA standard. We compared 60 combinations of the presence of repeated abnormal test locations at consecutive and semi-consecutive visits (tests confirmed at 2 consecutive, 3 consecutive, 2 of 3 visits, 3 of 4 and 2 of 4 each, at visual field locations ranging from 2 to 8).
Results: :
The optimal methods were: More than two locations confirmed in 3 out of 4 consecutive visits (sensitivity 67%-- specificity 80%). More than three locations confirmed in 3 out of 4 consecutive visits (sensitivity 60%-- specificity 83%). More than eight locations confirmed in 2 out of 4 consecutive visits (sensitivity 65%-- specificity 82%). GCP (2x4), GCP (8, 2x4) and GCP (3x4) (Vesti et al. 1999) show sub-optimality with respect to the change detection methods found above.
Conclusions: :
The presence of 4 or more abnormal test locations confirmed on semi-consecutive visits may be clinically useful and efficient methods of defining visual field change in glaucoma