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Peter L Nesper, Fabio Scarinci, Joseph Simonett, Amani A Fawzi; Photoreceptor outer segment disruption in diabetic macular ischemia. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5105.
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© ARVO (1962-2015); The Authors (2016-present)
The impact of diabetic macular ischemia (DMI) on the structural integrity and waveguiding properties of photoreceptors is largely unknown. Adaptive optics scanning laser ophthalmoscopy (AOSLO) achieves sufficient imaging resolution to study individual photoreceptor outer segments in the living human retina. We utilized the Apaeros AOSLO imaging system (Boston Micromachines Corporation, Boston) to assess photoreceptor characteristics in patients with DMI.
Fluorescein angiography (FA) images were analyzed to recruit patients with DMI. Diabetic eyes with normal retinal perfusion were included as controls. Exclusion criteria were media or lens opacities or retinal edema that resulted in poor resolution on AOSLO. After applying our criteria, 4 eyes with DMI and 3 control eyes were included for analysis. AOSLO images of the macula were obtained, montaged and overlaid onto FA and registered infrared images using vascular landmarks. This allowed point-to-point correlation between AOLSO, FA and SD-OCT (Spectralis HRA+OCT, Heidelberg Engineering, Germany) in order to assess photoreceptor integrity in areas of ischemia and normal perfusion.
In all 7 eyes, areas of robust capillary perfusion corresponded to bright, continuous cone outer segments on AOSLO, as well as intact inner segment-outer segment (IS/OS) junction and interdigitation zone (IZ) on SD-OCT. In 4 eyes with DMI, areas of non-perfusion highly correlated with photoreceptor disruption on AOSLO, suggesting loss or structural disruption of outer segments. These areas also corresponded to disrupted IS/OS junction and IZ on SD-OCT.
We report a correlation between areas of diabetic related nonperfusion and the absence of visible photoreceptor outer segments, suggesting that insufficient retinal circulation in DMI can result in a loss of outer retinal structures. This study also demonstrates a strong correlation between AOSLO and SD-OCT imaging of photoreceptors and highlights the ability of AOSLO technology to detect subtle outer retinal changes.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Fig. 1 Photoreceptor disruption in an enlarged and irregular foveal avascular zone. (A) Infrared, (B) Fluoroscien angiography, (C) Adaptive optics scanning laser ophthalmoscopy (AOSLO), (D) Registered SD-OCT images. Green boxes display extent of AOSLO overlay. Yellow arrows and line correspond to locations of ischemia in B, reduced photoreceptor signal in C, and disruption of photoreceptor layers in D.
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