title: Structural and functional effects of hemiretinal endodiathermy axotomy in cynomolgus macaques.
abstract: OBJECTIVE
  Outer retinal injury has been well described in glaucoma. To better understand the source of this injury, we wanted to develop a reliable model of partial retinal ganglion cell (RGC) axotomy.
  
  
  METHODS
  Endodiathermy spots were placed along the inferior 180° adjacent to the optic nerve margin in the right eyes of four cynomolgus monkeys. Fluorescein angiography, spectral domain optical coherence tomography (SD-OCT), and multifocal electroretinography (mfERG) were performed at various intervals. Two animals were sacrificed at 3 months. Two animals were sacrificed at 4 months, at which time they underwent an injection of fluorescent microspheres to measure regional choroidal blood flow. Retinal immunohistochemistry for glial fibrillary acidic protein (GFAP), rhodopsin, S-cone opsin, and M/L-cone opsin were performed, as were axon counts of the optic nerves.
  
  
  RESULTS
  At 3 months, there was marked thinning of the inferior nerve fiber layer on SD-OCT. The mfERG waveforms were consistent with inner but not outer retinal injury. Greater than 95% reduction in axons was seen in the inferior optic nerves but no secondary degeneration superiorly. There was marked thinning of the nerve fiber and ganglion cell layers in the inferior retinas. However, the photoreceptor histology was similar in the axotomized and nonaxotomized areas. Regional choroidal blood flow was not affected by the axotomy.
  
  
  CONCLUSIONS
  Unlike experimental glaucoma, hemiretinal endodiathermy axotomy (HEA) of the RGCs produces no apparent anatomic, functional, or blood flow effects on the outer retina and choroid.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792-3220, USA.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Dashek
authors.forename: Charlene B Y
authors.initials: CB
authors.lastname: Kim
authors.forename: Carol A
authors.initials: CA
authors.lastname: Rasmussen
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Hennes-Beean
authors.forename: James N
authors.initials: JN
authors.lastname: Ver Hoeve
authors.forename: T Michael
authors.initials: TM
authors.lastname: Nork
mesh_terms: D000818:Animals; D019771:Axotomy; D002829:Choroid / Q000098:blood supply; D004195:Disease Models, Animal; D004564:Electrocoagulation; D004596:Electroretinography; D005260:Female; D005451:Fluorescein Angiography; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007150:Immunohistochemistry; D008252:Macaca fascicularis; D008297:Male; D009412:Nerve Fibers / Q000473:pathology*; D055355:Opsins / Q000378:metabolism; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism / Q000473:pathology; D012160:Retina / Q000502:physiology*; D012162:Retinal Degeneration / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012171:Retinal Vessels / Q000502:physiology; D012243:Rhodopsin / Q000378:metabolism; D041623:Tomography, Optical Coherence
chemical_list: D005904:Glial Fibrillary Acidic Protein; D055355:Opsins; D012243:Rhodopsin
keywords: choroidal blood flow; endodiathermy axotomy; multifocal electroretinography; optical coherence tomography; photoreceptor morphology