Qualitative and quantitative characteristics of near-infrared autofluorescence in diabetic macular edema.

Objective: To study the characteristics of near-infrared autofluorescence (NIR-AF) imaging and its association with spectral-domain optical coherence tomography (SD-OCT) findings and logarithm of the minimal angle of resolution (logMAR) visual acuity (VA) in diabetic macular edema (DME).

Design: Retrospective, observational, cross-sectional study.

Participants: One hundred twenty-one consecutive eyes of 87 patients with center-involved DME for whom NIR-AF and SD-OCT images of sufficient quality were obtained.

Methods: The NIR-AF images were acquired using Heidelberg Retina Angiograph 2 (Heidelberg Engineering, Heidelberg, Germany), and sectional retinal images were obtained using Spectralis OCT (Heidelberg Engineering). The presence of a mosaic pattern and cystoid signs were determined qualitatively. We quantified the average fluorescence intensity in the central 1-mm subfield. The characteristics of the NIR-AF images were compared with the OCT findings and logMAR VA.

Main Outcome Measures: Qualitative and quantitative characteristics of the NIR-AF images and their association with SD-OCT findings and logMAR VA.

Results: Fifty-seven eyes with a mosaic pattern in the NIR-AF macular images had worse logMAR VA (0.355±0.239 vs. 0.212±0.235; P = 0.001), a thicker central subfield (CSF) (530±143 μm vs. 438±105 μm; P <0.001), and disrupted external limiting membrane (ELM; P <0.001) compared with 64 eyes without these findings. Forty-one eyes with a cystoid sign in the NIR-AF images had worse logMAR VA (0.393±0.233 vs. 0.221±0.234; P <0.001) and a thicker CSF (557±155 μm vs. 443±100 μm; P <0.001) than those without them; there were no significant differences in the ELM status. The relative fluorescence intensity in the central subfield in the NIR-AF images was correlated negatively with the CSF thickness and logMAR VA (R = 0.492, P <0.001 and R = 0.377, P <0.001, respectively). Eyes with foveal serous retinal detachment had lower levels of relative fluorescence intensity than those without it (0.751±0.191 vs. 0.877±0.154; P = 0.007); there was no association with the presence of foveal cystoid spaces, disrupted ELM, or hyperreflective foci in the outer retinal layers.

Conclusions: Novel qualitative and quantitative NIR-AF characteristics in the macula indicated the clinical relevance and suggested the pathogenesis in DME.