New perimetric techniques - A comparison between rarebit and frequency doubling technology perimetry in normal subjects and glaucoma patients

Purpose: To compare rarebit microdot perimetry (RB) with frequency doubling technology (FDT) perimetry in normal subjects and a group of patients with ocular hypertension or glaucoma, with age-matched controls. Materials and Methods: Eighty-one subjects (age 17-88 years) were examined. Twenty-seven of these were patients, aged 50 to 88 years, with ocular hypertension or suspected/manifest glaucoma in at least one eye. All subjects were examined with the RB and EDT perimetry, using the standard procedures, recommended by the respective manufacturer. Results: All patients were able to perform the RB perimetry, but three patients could not perceive the strongest FDT stimulus. The concordance in RB and FDT classifications as normal/outside normal limits was 96% (Cohen's kappa = 0.90). A curvilinear (quadratic) relationship (Rsq = 0.75) was found between RB hit rate and FDT MD. All patients, who could perform both examinations, preferred the R-B perimetry. Conclusion: In the current study, the information from the RB and FDT perimetry was almost completely equivalent. However, RB perimetry was preferred by the patients and seemed to have a larger dynamic range than FDT. The RB hit rate is apparently a straightforward and efficient measure of visual field function.