Abstract
Purpose :
Oxidative stress and mitochondrial dysfunction have been linked to the development of glaucoma by several authors. Previously, we reported increased flavoprotein fluorescence (FPF) in patients with moderate to advanced primary open-angle glaucoma (POAG) as compared to age-matched controls. In this study, we measured the level of FPF in eyes classified as glaucoma suspects (GS) and compared them to healthy controls and to patients receiving treatment for POAG.
Methods :
7 GS patients (7 eyes, mean age 56, range 48-68 years), 14 POAG patients (14 eyes, mean age 57, range 44-68 years), and 12 age-matched controls (12 eyes, mean age 52, range 42-65 years) were imaged with the OcuMet Beacon retinal metabolic analyzer (OcuSciences, Ann Arbor, MI). Images were obtained over 13-degree circular fields centered at the macula and optic disc. A histogram curve of pixel intensities for each image was generated. Average FPF intensity was calculated from all pixels within the circular field. FPF heterogeneity was determined from the width of the histogram curve at one-half the maximum FPF frequency (Fig. A). Unpaired Student’s t-tests were used to assess statistical significance.
Results :
Average FPF intensity was significantly higher in GS eyes compared to control eyes at both the macula (383±74 vs 290±77, p=0.021) and optic disc (407±58 vs 309±74, p=0.0093). FPF heterogeneity was significantly higher in GS eyes compared to control eyes at the optic disc (197±31 vs 134±31, p<0.001), but not at the macula (159±34 vs 126±44, p=0.10). Average FPF intensity and FPF heterogeneity of POAG eyes at the macula (374±114 and 151±39, respectively) and optic disc (390±110 and 176±44, respectively) were similar to glaucoma suspects (Fig. B).
Conclusions :
FPF appears sensitive to underlying mitochondrial dysfunction in GS eyes at both the macula and the optic disc and may prove a useful metric for identifying the earliest evidence of glaucoma. Lack of difference between GS and POAG patients may be due to effects of treatment on the POAG group. Longitudinal studies to correlate clinical variables to changes in FPF will help to define potential roles for the RMA in the detection and management of glaucomatous change.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.