title: Wavelength-dependent change of retinal nerve fiber layer reflectance in glaucomatous retinas.
abstract: OBJECTIVE
  Retinal nerve fiber layer (RNFL) reflectance is often used in optical methods for RNFL assessment in clinical diagnosis of glaucoma, yet little is known about the reflectance property of the RNFL under the development of glaucoma. This study measured the changes in RNFL reflectance spectra that occurred in retinal nerve fiber bundles with different degrees of glaucomatous damage.
  
  
  METHODS
  A rat model of glaucoma with laser photocoagulation of trabecular meshwork was used. Reflectance of the RNFL in an isolated retina was measured at wavelengths of 400-830 nm. Cytostructural distribution of the bundles measured optically was evaluated by confocal imaging of immunohistochemistry staining of cytoskeletal components, F-actin, microtubules, and neurofilaments. RNFL reflectance spectra were studied in bundles with normal-looking appearance, early F-actin distortion, and apparent damage of all cytoskeletal components. Changes of RNFL reflectance spectra were studied at different radii (0.22, 0.33, and 0.44 mm) from the optic nerve head (ONH).
  
  
  RESULTS
  Bundles in 30 control retinas and 41 glaucomatous retinas were examined. In normal retinas, reflectance spectra were similar along the same bundles. In glaucomatous retinas, reflectance spectra changed along bundles with the spectra becoming flatter as bundle areas approached the ONH.
  
  
  CONCLUSIONS
  Elevation of intraocular pressure (IOP) causes nonuniform changes in RNFL reflectance across wavelengths. Changes of reflectance spectra occur early in bundles near the ONH and prior to apparent cytoskeletal distortion. Using the ratio of RNFL reflectance measured at different wavelengths can provide early and sensitive detection of glaucomatous damage.
authors: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA. xhuang3@med.miami.edu
authors: Xiang-Run
authors: XR
authors: Huang
authors: Ye
authors: Y
authors: Zhou
authors: Robert W
authors: RW
authors: Knighton
authors: Wei
authors: W
authors: Kong
authors: William J
authors: WJ
authors: Feuer
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001369:Axons / Q000378:metabolism*; D004195:Disease Models, Animal; D005260:Female; D005901:Glaucoma / Q000378:metabolism*; D007429:Intraocular Pressure; D008027:Light; D008870:Microtubules / Q000378:metabolism; D016900:Neurofilament Proteins / Q000378:metabolism; D009898:Optic Disk / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012164:Retinal Diseases / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000378:metabolism*; D012542:Scattering, Radiation; D014065:Tonometry, Ocular
chemical_list: D000199:Actins; D016900:Neurofilament Proteins