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Mark Kupersmith, Mona Garvin, Jui-Kai Wang, Randy Kardon; Early Retinal Ganglion Cell Layer Thinning Due to Acute NAION and Optic Neuritis. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3233.
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© ARVO (1962-2015); The Authors (2016-present)
OCT shows retinal ganglion cell layer (GCL) loss correlation with RNFL thinning and vision loss due to glaucoma and multiple sclerosis but it has not been studied with acute optic neuropathy. We hypothesize that GCL loss occurs before RNFL loss detection, particularly with optic nerve head (ONH) swelling. GCL could provide another structure-function interaction to evaluate acute optic nerve injury.
We prospectively studied eyes with new onset NAION (36) and optic neuritis [(ON) 28] using SAP and HD OCT volume images centered on the ONH and macula. Using The University of Iowa graph-theoretic approach for layer segmentation, the combined GCL and inner-plexiform-layer (GCL+IPL) thickness was computed within an elliptical annulus centered at the fovea (with a vertical inner and outer radius of 0.5 mm and 2.0 mm, respectively; and horizontal inner and outer radius of 0.6 mm and 2.4 mm, respectively). We report average RNFL and macula GCL+IPL values at presentation and change at 1 month.
At presentation, the mean for the average GCL+IPL value for affected eyes, 80 µm + 8.1 for NAION and 83 µm + 8.9 for ON, did not differ from unaffected fellow eyes (83 + 6.4 and 82 + 7.0; NS). GCL thinning worsened in both groups over time (Figure: NAION pattern, ON white). At presentation, 5 NAION and 2 ON eyes had GCL+IPL < 5th percentile of unaffected eyes. RNFL thinning <5th percentile of controls (in none at presentation) developed in 4 NAION and 3 ON eyes at 1 month. At 1 month, 29 NAION and 19 ON eyes had GCL+IPL thinning > 3.2 µm (95th percentile for retest unaffected eyes, mean 0.13 + 1.2 µm), with mean thinning 17.2 µm + 12.3 and 9.0 µm + 6.2, respectively for NAION and ON eyes (p=0.001). At 1 month, GCL+IPL thinning correlated with Logmar acuity (r=0.62, p=0.01) and mean deviation (r=0.60, p=0.01) for NAION but not for ON eyes.
GCL thinning occurs rapidly in NAION and ON, but it is more profound in NAION. RGC loss occurs prior to RFNL thinning, making it a better biomarker of early structural loss.
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