Abstract
Purpose :
Functional and structural deficits have been reported in the retina of amblyopic eyes compared with fellow eyes. Non-invasive in vivo flavoprotein fluorescence (FPF) imaging provides clinic-based quantitative physiological biomarkers of retinal metabolic function. Based on previous studies in eyes with diabetic retinopathy and glaucoma exhibiting mitochondrial dysfunction, we hypothesized that amblyopic eyes would have higher levels of oxidized mitochondrial flavoproteins (FPF intensity and curve width) than those of fellow non-amblyopic eyes.
Methods :
14 children (aged 5y to 11y) with unilateral anisometropic, strabismic, or combined amblyopia underwent retinal metabolic imaging with the OcuMet Beacon (Ann Arbor, MI). The FPF sampling space was a 13° diameter target centered on the fovea identified with an IR alignment after pupil dilation. Retinal mitochondrial flavoprotein enzymes were activated for 30ms with an excitation wavelength of 467nm; emission filters were tuned to 535nm. Images were reviewed by an investigator masked to the clinical and FPF parameters and excluded if poor quality or decentered. We compared mean FPF intensity values and curve width between amblyopic and fellow eyes using paired t-tests, calculating mean difference with 95% confidence intervals (CI). We hypothesized that if there was a difference between amblyopic and fellow eyes, the mean difference of FPF intensity would be at least 5 units higher in affected eyes (based on studies in diabetic retinopathy).
Results :
9 pairs of images were graded by the masked grader as sufficient quality for analysis. Included children ranged from age 5 to 11 years and amblyopic eye acuity from 20/80 to 20/30. There was no statistically significant difference in FPF intensity between amblyopic and fellow eyes (mean difference -1.6 units, p=0.27) and the 95% CI (-4.59 to 1.47) excluded the hypothesized +5 unit mean difference. There was no difference in FPF curve width between amblyopic and fellow eyes (-1.33 units, 95% CI -2.72 to 0.05, p=0.06).
Conclusions :
In contrast to previous reports of functional and structural deficits in the retinas of eyes with amblyopia, we found no evidence of retinal mitochondrial dysfunction by flavoprotein fluorescence (assuming an expected effect size of 5 intensity units greater in amblyopia). Retinal changes in amblyopia do not appear to manifest as abnormalities in retinal mitochondrial function.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.