Aims: To demonstrate ultrahigh-resolution, three-dimensional optical coherence tomography (3D-OCT) and projection OCT fundus imaging for enhanced visualisation of outer retinal pathology in non-exudative age-related macular degeneration (AMD).
Methods: A high-speed, 3.5 μm resolution OCT prototype instrument was developed for the ophthalmic clinic. Eighty-three patients with non-exudative AMD were imaged. Projection OCT fundus images were generated from 3D-OCT data by selectively summing different retinal depth levels. Results were compared with standard ophthalmic examination, including fundus photography and fluorescein angiography, when indicated.
Results: Projection OCT fundus imaging enhanced the visualisation of outer retinal pathology in non-exudative AMD. Different types of drusen exhibited distinct features in projection OCT images. Photoreceptor disruption was indicated by loss of the photoreceptor inner/outer segment (IS/OS) boundary and external limiting membrane (ELM). RPE atrophy can be assessed using choroid-level projection OCT images.
Conclusions: Projection OCT fundus imaging facilities rapid interpretation of large 3D-OCT data sets. Projection OCT enhances contrast and visualises outer retinal pathology not visible with standard fundus imaging or OCT fundus imaging. Projection OCT fundus images enable registration with standard ophthalmic diagnostics and cross-sectional OCT images. Outer retinal alterations can be assessed and drusen morphology, photoreceptor impairment and pigmentary abnormalities identified.
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Competing interests: JSS: Carl Zeiss Meditec, Heidelberg Engineering, Optovue—compensation. JSD: Carl Zeiss Meditec, Optovue—affiliation. JGF receives royalties from intellectual property owned by MIT and licensed to Carl Zeiss Meditec and Lightlabs Imaging, and is on the scientific advisory board of and has stock options in Optovue.
Funding: National Institute of Health contracts R01-EY11289-23, R01-EY13178-09, R01-EY013516-06, P30-EY08098 and P30-EY13078; National Science Foundation contract BES-0522845; Air Force Office of Scientific Research, Medical Free Electron Laser Program contracts FA9550-07-1-0101 and FA9550-07-1-0014; The Eye and Ear Foundation (Pittsburgh), Massachusetts Lions Eye Research Fund; unrestricted grants from Research to Prevent Blindness and Medical Student Eye Research Fellowship.
Ethics approval: Ethics approval was provided by the institutional review boards of Tufts Medical Center and MIT.
Patient consent: Obtained.
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