Retinal Nerve Fiber Layer Thickness Measurements: Uveitis, A Major Confounding Factor

To evaluate optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) measurements in patients with active and quiescent uveitis with and without glaucoma and compare results to the published age-adjusted normative data.Comparative, retrospective pilot study.Consecutive patients with uveitis who underwent OCT RNFL measurements between December 2011 and October 2012 were identified: 76 uveitic eyes without glaucoma and 135 uveitic eyes with glaucoma.We conducted OCT of the RNFL.Global and sectoral RNFL thickness measurements.In 19 nonglaucomatous, uveitic eyes with active inflammation, mean global and all sectoral RNFL measurements were greater than the normative 95th percentile. The mean global RNFL OCT measurement was 140.5 microns in such eyes compared with 107.8 microns in the 57 nonglaucomatous, quiescent, uveitic eyes (P=0.008). These measurements were significantly higher than the average of 95.3 microns reported in normal eyes (P<0.001). All mean sectoral measurements except superonasal were significantly higher in active compared with quiescent uveitic eyes (P=0.002-0.05). In glaucomatous eyes with both quiescent and active uveitis, the mean global RNFL measurements on OCT were 92.3 and 95.7 microns, respectively. These measurements were significantly higher than the mean global RNFL thickness (65.3 microns) reported in eyes with the same stage (moderate) of nonuveitic glaucoma.Uveitis is a major confounding factor in assessing the thickness of the RNFL. A significant thickening of the RNFL was found in patients with active uveitis and a greater RNFL thickness than anticipated in patients with uveitic glaucoma. These data raise concerns about the comparative value of RNFL scans as a method to detect and monitor glaucoma in uveitic eyes.