PURPOSE. To evaluate optical coherence tomography (OCT) measurement of peripapillary retinal nerve fiber layer (RNFL) thickness in patients with mild papilledema associated with idiopathic intracranial hypertension. METHODS. Patients with papilledema underwent a complete ophthalmic examination, including peripapillary RNFL analysis with OCT (Fast RNFL thickness 3.46; Carl Zeiss Meditec, Inc., Dublin, CA) at diagnosis and 3, 6, and 12 months after presentation. Age- and sex-matched control subjects underwent a similar evaluation. Changes in RNFL overall thickness and by quadrant and interocular differences were evaluated and studied regarding changes in visual field global indices (mean deviation [MD] and pattern SD [PSD]). RESULTS. Both eyes of 22 patients with mild papilledema and 22 control subjects were included. At diagnosis, the RNFL thickness was 183.3 +/- 74.7 mu m and 74.9% (78.5 mu m) greater than in control eyes. Mean RNFL thicknesses in all quadrants were significantly greater in eyes with papilledema (P = 0.000). The mean average RNFL was significantly correlated with the MD (sigma = -0.451, P = 0.002) and PSD (sigma = 0.370, P = 0.013) at diagnosis. The RNFL thickness decreased significantly (P = 0.000), whereas the mean MD and the mean PSD improved (P = 0.000 and P = 0.005, respectively) at each follow-up visit. Regression analysis showed that for every 10 mu m of mean RNFL thickness increase at baseline, there was a 0.6-dB decrease in MD at the last follow-up. CONCLUSIONS. Peripapillary RNFL thickness abnormalities assessed by OCT in patients with mild papilledema were quantitatively correlated with visual field sensitivity losses. The data support the possible use of OCT as a noninvasive quantitative method of monitoring the amount and evolution of papilledema. (Invest Ophthalmol Vis Sci. 2009;50:5197-5200) DOI:10.1167/iovs.08-2528