A staged approach to the number and frequency of visual field testing for detecting glaucoma progression

PURPOSE: To assess a staged visual field review model (initially intensive, then downtitrated) for detecting cases of glaucoma progression (especially catastrophic and fast), in comparison to clinical standard, fixed review approaches. DESIGN: Computer simulation study. SUBJECTS: 100,000 subjects. METHODS: 100,000 subjects were simulated to undergo four VF tests in one "eye" per visit, 3 monthly, over 30 years. The staged visual field model consisted of an initial intensive review (e.g. three tests per eye per visit, 3 monthly) that was then downtitrated as 90% of progressors within a rate bin (e.g. catastrophic <-2 dB/year) was detected. The test number and review cadence were systematically downtitrated with 90% of successive progression rate bins detected until the end of the 30 year follow up. Comparator models were fixed reviews: one test 12 monthly, one test 6 monthly, two tests 6 monthly ("frontloading") and three tests 24 monthly ("wait-and-see"). To reduce false positives, an immediate subsequent confirmatory progression result was required for all conditions. MAIN OUTCOME MEASURES: Number of progressors detected and number of tests/visits required per case of progression detected. RESULTS: All staged review approaches detected 90% of catastrophic (21-36 months) and fast (36-60 months) progression bins sooner compared to all fixed methods (catastrophic: 66-108 months; fast: 84-132 months) except fixed frontloading. Detection of 50% of all progressors was also achieved sooner for the staged approaches (21-36 months) compared to all fixed methods (60-96 months), except for fixed frontloading (36 months). When using one test 12 monthly as a reference standard, the staged approaches were 66%-251% more likely to detect progression. The two tests per visit at 3 monthly and 6 monthly staged intervals were the most efficient with the lowest number of visits (10.6 and 8.6 at 5 years) and tests (15.8 and 12.9 at 5 years) per case detected over time. CONCLUSIONS: A staged visual field review model starting with intensive testing (such as two tests per visit at 3 or 6 monthly intervals) with downtitration at 30-36 months may increase the likelihood of detecting progressors and may provide long-term efficiencies in case detection, in comparison to conventional fixed approaches.