title: Retinal Ganglion Cell Layer Thinning Within One Month of Presentation for Non-Arteritic Anterior Ischemic Optic Neuropathy.
abstract: OBJECTIVE
  Optical coherence tomography reveals retinal ganglion cell layer (GCL) and retinal nerve fiber layer (RNFL) thinning in chronic optic nerve injury. With acute optic nerve injury, as in acute nonarteritic anterior ischemic optic neuropathy (NAION), swelling obscures early demonstration of RNFL thinning, which might be used to evaluate therapies. We hypothesized that measurement of GCL plus inner plexiform layer (IPL) thickness and trajectory of thinning would show it is an earlier and more accurate biomarker of early permanent neuronal injury.
  
  
  METHODS
  We prospectively studied 29 acute NAION eyes with standard automated perimetry and spectral domain (SD) optical coherence tomography for 6 months. We used a three-dimensional layer segmentation (method 1) and a commercial proprietary (method 2), to compute the combined thickness of macular GCL+IPL and method 2 to compute peripapillary RNFL thickness.
  
  
  RESULTS
  At presentation, the mean GCL+IPL thickness (78.7 μm ± 8.9) for NAION eyes, did not differ from unaffected fellow eyes (83 μm ± 6.4), using method 1 while method 2 (66.8 μm ± 18.7) failed in 34% of NAION eyes. At 1 to 2 months, 12% had RNFL loss compared to baseline, while 68% of NAION eyes had GCL+IPL thinning. The ganglion cell layer plus inner plexiform layer reduction was greatest at 1 to 2 months (19.6 μm ± 12.6) and was minimally worse after month 3. Ganglion cell layer plus inner plexiform layer thinning showed moderate to strong significant correlation with the visual acuity and mean deviation at each exam time. The retinal nerve fiber layer was not thinned until month 3.
  
  
  CONCLUSIONS
  Ganglion cell layer plus inner plexiform layer is acutely unaffected and provides a reliable measure of retinal neuronal structure using three-dimensional segmentation. Thinning develops within 1 to 2 months of onset, which is prior to RNFL swelling resolution. This suggests GCL+IPL measurement is better than the RNFL thickness to use as biomarker of early structural loss in NAION.
authors.affiliation: New York Eye and Ear Infirmary and INN at Mount Sinai West Hospital New York, New York, United States.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Kupersmith
authors.affiliation: Department of Electrical and Computer Engineering, The University of Iowa, Iowa City, Iowa, United States 3Department of Ophthalmology, Iowa University School of Medicine and Center for Prevention and Treatment of Visual Loss, Veterans Administration, Iow.
authors.forename: Mona K
authors.initials: MK
authors.lastname: Garvin
authors.affiliation: Department of Electrical and Computer Engineering, The University of Iowa, Iowa City, Iowa, United States.
authors.forename: Jui-Kai
authors.initials: JK
authors.lastname: Wang
authors.affiliation: Carl Zeiss-Meditec, Inc., Dublin, California, United States.
authors.forename: Mary
authors.initials: M
authors.lastname: Durbin
authors.affiliation: Department of Ophthalmology, Iowa University School of Medicine and Center for Prevention and Treatment of Visual Loss, Veterans Administration, Iowa City, Iowa, United States.
authors.forename: Randy
authors.initials: R
authors.lastname: Kardon
mesh_terms: D000368:Aged; D001766:Blindness / Q000473:pathology; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008297:Male; D009900:Optic Nerve / Q000473:pathology / Q000503:physiopathology; D018917:Optic Neuropathy, Ischemic / Q000473:pathology* / Q000503:physiopathology; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000473:pathology*; D013997:Time Factors; D041623:Tomography, Optical Coherence