['To evaluate the associations between retinal nerve fiber layer (RNFL) thickness and lipid profiles in multiple sclerosis (MS).', 'This study enrolled 136 patients with MS (n = 272 eyes; 108 females, 28 males, mean age: 46.7 ± 8.9 years); 45% had a history of optic neuritis (ON). Subjects received optical coherence tomography (OCT) testing to assess RNFL thickness and visual acuity testing with Snellen charts. A subset of 88 patients received pattern reversal visual-evoked potential (PRVEP) testing. Lipid profiles consisting of serum high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol and total cholesterol (TC) levels were obtained within ± 6 months of OCT. Regression analyses were used to assess the associations between RNFL thickness and lipid profile variables.', 'Low RNFL thickness (P = 0.008) and higher PRVEP latency (P = 0.017) were associated with high LDL cholesterol > 100 mg/dl status. Low RNFL thickness (P = 0.008) and higher PRVEP latency (P = 0.043) were associated with high HDL cholesterol levels. Low RNFL thickness was also associated with HDL cholesterol > 60 mg/dl status (P = 0.001) and with TC > 200 mg/dl status (P = 0.015). The probability of average RNFL thickness in the lowest tertile (≤ 33rd percentile) was associated with interactions between TC > 200 mg/dl status (P = 0.001, odds ratio = 7.5, 95% confidence interval = 2.7-21) with affected/unaffected by ON status.'] Does cholesterol affect retinal nerve fiber layer thickness in patients with multiple sclerosis with optic neuritis?