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Frequency Doubling Technology (FDT) perimetry was introduced as a clinical ophthalmic diagnostic tool approximately twenty years ago1,2 It has now been upgraded to a second-generation device known as the Humphrey Matrix, which has better spatial mapping of visual field sensitivity and many other enhancements to the test procedure.3 These devices are now in use by more than 20,000 eye care specialists worldwide. Originally, FDT perimetry was mainly considered to be a procedure that was useful for visual field screening to detect sensitivity losses that were associated with glaucoma and other ocular and neurologic disorders.
It is possible to monitor glaucomatous visual field properties longitudinally with FDT, that FDT results can be predictive of glaucomatous progression
The ability of this form of testing to monitor glaucoma patients over time has received only limited attention to date, although several investigations have reported that it is able to monitor change over time and may be predictive of future visual field loss using standard automated perimetry with longitudinal studies that have been conducted for several years with a relatively small number of patients.4-8 The present study represents a noteworthy departure from this trend by following a large number of patients currently enrolled in two longitudinal clinical trials by a team of investigators with extensive experience in this area. Five hundred and eighty-seven eyes from 367 patients with suspected glaucoma were tested with an average of seven times over an average of six years with the Humphrey Matrix FDT perimeter and the Humphrey Field Analyzer. Baseline FDT results, and pattern standard deviation (PSD) and slope of FDT results were predictive of glaucomatous visual field progression, and the longitudinal model was better than the baseline model. These findings demonstrate that it is possible to monitor glaucomatous visual field properties longitudinally with FDT, that FDT results can be predictive of glaucomatous progression and that a team approach can accomplish more than individual single investigator efforts. The authors should be congratulated for a highly successful and informative study that demonstrates the effectiveness of FDT in monitoring glaucomatous visual field change over time.