Correlation of fundus autofluorescence with spectral-domain optical coherence tomography and vision in diabetic macular edema

Abstract

Purpose: To investigate the correlation between fundus autofluorescence (FAF) and the results of spectral-domain optical coherence tomography (SD-OCT) as well as visual acuity (VA) in patients with diabetic macular edema (DME) and to determine the visual prognostic factors.

Design: Retrospective, interventional case series.

Participants: Sixty-one patients with DME who underwent intravitreal injection of bevacizumab (IVB) as their first treatment.

Methods: An assessment of VA and FAF and SD-OCT images were obtained before and after IVB (pre- and post-IVB). Foveal FAF was graded on a scale of 1 to 4. The presence or absence of FAF at the foveola was also determined.

Main outcome measures: The association of FAF with VA and the SD-OCT results, including central macular thickness (CMT), outer nuclear layer thickness, the integrity of the external limiting membrane (ELM), and the integrity of the junction between the inner and outer segment of the photoreceptor (IS/OS).

Results: Better VA, preservation of the ELM, and IS/OS pre-IVB were associated with better VA post-IVB. Of the types of DME, cystoid macular edema significantly correlated with increased FAF at the foveola. A higher level of FAF was 5.6 times more likely to occur in DME with a defect in IS/OS and 10 times more likely to occur with each 10-μm increase in CMT. Each increase by a factor of 0.1 in the logarithm of the minimum angle of resolution (logMAR) pre-IVB increased the probability of high FAF by a factor of 1.73. Despite severe DME, fewer eyes with a low level of FAF exhibited an IS/OS defect and large logMAR VA than eyes with a high level of FAF with severe DME pre-IVB. The average grade of FAF pre-IVB was higher in patients with decreased vision during follow-up than in patients with increased or unchanged good vision.

Conclusions: The strong association of FAF with SD-OCT parameters and VA in patients with DME could aid in the prediction of the restoration of photoreceptor integrity and subsequent visual recovery, especially in patients with severe DME, in whom photoreceptor integrity before treatment could not be adequately evaluated, even with SD-OCT.