title: EXPLORING PHOTORECEPTOR REFLECTIVITY THROUGH MULTIMODAL IMAGING OF OUTER RETINAL TUBULATION IN ADVANCED AGE-RELATED MACULAR DEGENERATION.
abstract: OBJECTIVE
  To investigate the microscopic structure of outer retinal tubulation (ORT) and optical properties of cone photoreceptors in vivo, we studied ORT appearance by multimodal imaging, including spectral domain optical coherence tomography (SD-OCT) and adaptive optics scanning laser ophthalmoscopy.
  
  
  METHODS
  Four eyes of four subjects with advanced age-related macular degeneration underwent color fundus photography, infrared reflectance imaging, SD-OCT, and adaptive optics scanning laser ophthalmoscopy with a high-resolution research instrument. Outer retinal tubulation was identified in closely spaced (11 μm) SD-OCT volume scans.
  
  
  RESULTS
  Outer retinal tubulation in cross-sectional and en face SD-OCT was a hyporeflective area representing a lumen surrounded by a hyperreflective border consisting of cone photoreceptor mitochondria and external limiting membrane, per previous histology. In contrast, ORT by adaptive optics scanning laser ophthalmoscopy was a hyporeflective structure of the same shape as in en face SD-OCT but lacking visualizable cone photoreceptors.
  
  
  CONCLUSIONS
  Lack of ORT cone reflectivity by adaptive optics scanning laser ophthalmoscopy indicates that cones have lost their normal directionality and waveguiding property due to loss of outer segments and subsequent retinal remodeling. Reflective ORT cones by SD-OCT, in contrast, may depend partly on mitochondria as light scatterers within inner segments of these degenerating cells, a phenomenon enhanced by coherent imaging. Multimodal imaging of ORT provides insight into cone degeneration and reflectivity sources in optical coherence tomography.
authors: *Vision Science Graduate Program, University of Alabama at Birmingham, Birmingham, AL; †Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama; ‡Vitreous Retina Macula Consultants of New York, New York, New York; and §Department of Ophthalmology, New York University School of Medicine, New York, New York.
authors: Katie M
authors: KM
authors: Litts
authors: Xiaolin
authors: X
authors: Wang
authors: Mark E
authors: ME
authors: Clark
authors: Cynthia
authors: C
authors: Owsley
authors: K Bailey
authors: KB
authors: Freund
authors: Christine A
authors: CA
authors: Curcio
authors: Yuhua
authors: Y
authors: Zhang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D064847:Multimodal Imaging; D009887:Ophthalmoscopy / Q000379:methods; D055095:Optics and Photonics / Q000379:methods; D017949:Retinal Cone Photoreceptor Cells / Q000473:pathology*; D055214:Retinal Photoreceptor Cell Outer Segment / Q000473:pathology*; D041623:Tomography, Optical Coherence