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Jui-Kai Wang, Mark J Kupersmith, Mona K Garvin, Randy H Kardon; Retinal Ganglion Cell Layer Thinning and Vision Outcome in NAION and Optic Neuritis over Six Months. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5780.
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© ARVO (1962-2015); The Authors (2016-present)
We previously showed that retina ganglion cell layer (GCL) thinning occurs within one month of acute optic neuritis (ON) and non-arteritic anterior ischemic optic neuropathy (NAION), long before retinal nerve fiber layer (RNFL) thinning or complete loss of acute swelling are seen (ARVO 2013). Here we investigate the trajectory of GCL thinning over 6 months in both disorders in order to determine when most of the loss occurs and how the amount of GCL loss relates to the visual outcome.
Using spectral domain optical coherence tomography (SD-OCT, Cirrus 4000) of the optic nerve head and macula areas, we prospectively evaluated 29 eyes (age 36±10) with new onset ON and 29 eyes (age 65±12) with NAION within 2 weeks of vision loss (acute stage), at one month and at 6 months. We used 3D-segmentation to calculate the GCL plus inner plexiform layer thickness for each macula image.
The maximum amount of GCL thinning occurred at 1 month with mean loss of 19.62 µm ± 12.62 for NAION and 8.68 µm ± 5.09 for ON eyes. A modest, further thinning of the GCL occurred between 3 and 6 months in NAION (6.11 µm and 1.11 µm, respectively) and in ON (2.61 µm and 0.62 µm, respectively). The amount of GCL thinning at 1 month strongly correlated with the amount of GCL loss at 6 months in NAION (r=0.854) and in ON (r=0.838) eyes. There was also a significant correlation between the GCL thickness at one month and the mean deviation of the visual field for NAION eyes (r= 0.507) but not in ON eyes (r=0.052). The RNFL was thickened, particularly in NAION eyes, at presentation and 1 month and did not correlate with mean deviation of the visual field in either NAION or ON at that time point. The RNFL did not show thinning until the 3 and 6-month time points.
For acute ON and NAION, the largest proportion of GCL loss has already occurred at one month (in contrast to the RNFL, due to continued swelling) and suggests that neural preservation or protection therapy must be delivered earlier than one month to significantly prevent loss of retinal ganglion cells in both disorders.
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