A variety of systems are used to track visual field progression, including classification systems (including several scoring systems), event analysis (such as Glaucoma Change Progression and Glaucoma Progression Analysis), and trend analysis (such as Progressor and Linear Regression).
Each approach has pros and cons.
“Event analysis is designed to detect progression but not necessarily the rate,” Dr. Johnson said.
“Trend analysis gives the rate of progression, which is important,” he said. “Event analysis looks at change from baseline, while trend analysis examines all the data. In general, event analysis, given the right decision criteria, can detect progression earlier than trend analysis. But rate of progression is a critical factor for patient management.”
Research done by Dr. Johnson and colleagues has found that the follow-up time to determine visual field progression varies two- to three-fold depending on the kind of trend or event analysis used and the decision criteria.
“The critical thing is that they only agree with each other 50% to 60% of the time,” Dr. Johnson said. “This illustrates that no single test or method of analyzing can give you the final result.”