title: Optical Detection of Early Damage in Retinal Ganglion Cells in a Mouse Model of Partial Optic Nerve Crush Injury.
abstract: OBJECTIVE
  Elastic light backscattering spectroscopy (ELBS) has exquisite sensitivity to the ultrastructural properties of tissue and thus has been applied to detect various diseases associated with ultrastructural alterations in their early stages. This study aims to test whether ELBS can detect early damage in retinal ganglion cells (RGCs).
  
  
  METHODS
  We used a mouse model of partial optic nerve crush (pONC) to induce rapid RGC death. We confirmed RGC loss by axon counting and characterized the changes in retinal morphology by optical coherence tomography (OCT) and in retinal function by full-field electroretinogram (ERG), respectively. To quantify the ultrastructural properties, elastic backscattering spectroscopic analysis was implemented in the wavelength-dependent images recorded by reflectance confocal microscopy.
  
  
  RESULTS
  At 3 days post-pONC injury, no significant change was found in the thickness of the RGC layer or in the mean amplitude of the oscillatory potentials measured by OCT and ERG, respectively; however, we did observe a significantly decreased number of axons compared with the controls. At 3 days post-pONC, we used ELBS to calculate the ultrastructural marker (D), the shape factor quantifying the shape of the local mass density correlation functions. It was significantly reduced in the crushed eyes compared with the controls, indicating the ultrastructural fragmentation in the crushed eyes.
  
  
  CONCLUSIONS
  Elastic light backscattering spectroscopy detected ultrastructural neuronal damage in RGCs following the pONC injury when OCT and ERG tests appeared normal. Our study suggests a potential clinical method for detecting early neuronal damage prior to anatomical alterations in the nerve fiber and ganglion cell layers.
authors: Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States.
authors: Ji
authors: J
authors: Yi
authors: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China 3Department of Ophthalmology, Northwestern University, Chicago, Illinois, United States.
authors: Zhen
authors: Z
authors: Puyang
authors: Department of Ophthalmology, Northwestern University, Chicago, Illinois, United States.
authors: Liang
authors: L
authors: Feng
authors: Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States.
authors: Lian
authors: L
authors: Duan
authors: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors: Peiji
authors: P
authors: Liang
authors: Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States.
authors: Vadim
authors: V
authors: Backman
authors: Department of Ophthalmology, Northwestern University, Chicago, Illinois, United States 4Department of Neurobiology, Northwestern University, Evanston, Illinois, United States.
authors: Xiaorong
authors: X
authors: Liu
authors: Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States 3Department of Ophthalmology, Northwestern University, Chicago, Illinois, United States.
authors: Hao F
authors: HF
authors: Zhang
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004596:Electroretinography; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D009412:Nerve Fibers / Q000473:pathology; D009900:Optic Nerve / Q000473:pathology*; D020221:Optic Nerve Injuries / Q000175:diagnosis*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods*