Purpose.: To evaluate the ability of Fourier-domain (FD) optical coherence tomography (OCT) to detect retinal nerve fiber layer (RNFL) atrophy in multiple sclerosis (MS) patients. To test the intrasession reproducibility of RNFL thickness measurements in MS and healthy subjects using Cirrus (Carl Zeiss Meditec, Dublin, CA) and Spectralis (Heidelberg Engineering, Heidelberg, Germany) OCT. Methods.: Two hundred twenty-two eyes of 111 subjects (50 MS patients and 61 healthy subjects) underwent three 360° circular scans centered on the optic disc by the same experienced examiner using the Cirrus and Spectralis OCT instruments. Differences between healthy and MS eyes were compared. The relationship between average thicknesses with each OCT was evaluated. Repeatability was studied by intraclass correlation coefficients and coefficients of variation (COV). Results.: RNFL atrophy was detected in the MS eyes for all OCT parameters (P < 0.05). Cirrus and Spectralis showed an RNFL average thickness of 99.4 and 102.5 μm, respectively, in healthy subjects, and 86.0 and 90.4 μm in the MS eyes. RNFL average thickness in the MS eyes determined by both OCTs correlated (r = 0.812; P < 0.001), but were significantly different (P < 0.001). Reproducibility was good. In the MS eyes, Cirrus measurements showed a mean COV of 5.85%, Spectralis 6.80%, and Spectralis with a progression feature 4.16%. Intraclass correlation coefficients were higher than 0.840. RNFL average thickness correlated with disease duration and an optic neuritis antecedent. Conclusions.: There are significant differences in RNFL thickness measurements between Cirrus and Spectralis despite a high correlation of measurement between the two instruments. Fourier-domain OCT can be considered a valid device for detecting RNFL atrophy in MS patients.

Acta Ophthalmol. 2011: 89: e23–e29 Purpose: To test intrasession, intersession, intervisit and interoperator reproducibility of retinal nerve fibre (RNFL) measurements and retinal thickness in healthy subjects using Cirrus Fourier-domain optical coherence tomography (OCT) (Carl Zeiss Meditec, Inc). Methods: Seventy-two eyes of 72 healthy subjects were included in the study. All the eyes underwent three 512 × 128 volume cube centred on the fovea and three 360° circular scans centred on the optic disc by one observer. This sequence was redone by another observer on a second visit within a 2-week period. Descriptive statistics, analysis of variance, intraclass correlation coefficients (ICCs) and coefficients of variation (COVs) were calculated for the nine areas corresponding to the Early Treatment Diabetic Retinopathy Study and for quadrants and RNFL clock hr sectors. Results: Retinal thickness and RNFL measurements were highly reproducible. Mean total retinal thickness was 285.2 ± 15.3 μm by observer 1 and 284.2 ± 12.9 μm by observer 2. Mean COV was 1.2%. Mean RNFL average thicknesses were 96.0 ± 7.7 and 95.7 ± 7.9 μm by observer 1 and 2, respectively. Mean COV was 4.4%. The ICCs ranged from 0.823 to 0.992. Mean differences between both operators were lower than 3 μm, and no significant differences were found. Conclusions: Retinal and RNFL thickness measurements obtained using Cirrus OCT show good repeatability for healthy eyes and few differences between intra- and interobserver evaluations. It can be considered a valid device for measuring retinal and optic nerve parameters in normal eyes.

Purpose: To quantify changes in the retinal nerve fiber layer (RNFL) of patients with multiple sclerosis (MS) over a 1-year time period and to compare the ability of noninvasive diagnostic imaging devices and visual evoked potentials (VEP) to detect axonal loss in these patients. Methods: Eighty-one patients with MS underwent a complete ophthalmic examination that included assessment of visual acuity and color vision, refractive evaluation, visual field examination, optical coherence tomography (OCT), scanning laser polarimetry (GDx), and measurement of VEP. All the patients were re-evaluated after a period of 12 months in order to quantify any change in the RNFL. Only one randomly chosen eye from each patient was included in the study. Results: Statistically significant differences between the 2 examinations were recorded for the overall mean and inferior RNFL thickness and the macular volume, as assessed by OCT, as well as for the temporal-superior-nasal-inferior-temporal average standard deviation provided by GDx. The greatest differences were obtained for the mean RNFL thickness (90.46 μm vs 85.96 μm). Changes in the optic nerve were detected by structural measurements but not by functional assessments. Conclusions: Axonal loss in the optic nerve of patients with MS is greater than that expected in healthy subjects, regardless of the presence of a previous optic neuritis.