Reproducibility of retinal thickness measurements in eyes with uveitic macular edema using Spectralis Optical Coherence Tomography L. Iannetti, G. Spinucci, R. Abdulaziz, P. Tortorella, P. Pivetti-Pezzi “Sapienza” University of Rome Department of Ophthalmology Ocular Immunovirology Service Paris 2010 10th Euretina Congress

INTRODUCTION Macular edema is one of the most frequent and sight-threatening complications of uveitis. Optical Coherence Tomography (OCT) is widely used for quantitative detection of macular edema and permits a sensitive analysis of macular thickness. Spectral domain OCT provides increased resolution and scanning speed using a Fourier domain spectrometric method. Reproducibility of measurements is an essential tool in determining the utility of OCT for clinical use. Reproducibility is the variability of measurements obtained under different conditions e.g. by a different operator or in a different visit. The aim of the present study is to value the reproducibility of retinal thickness measurements in eyes with uveitic macular edema of the spectral-domain Optical Coherence Tomography (Spectralis OCT; Heidelberg Engineering, Heidelberg, Germany)

METHODS Forty-two eyes (33 patients) affected by uveitis complicated by macular edema were included into the study. Uveitis was anterior in 4 eyes (9.5%), intermediate in 18 (42.8%), posterior in 7 (16.7%) and diffuse in 13 (31%). Mean duration of uveitis was 72 months. All patients underwent Spectralis OCT examination. For retinal thickness measurements, 20 x15 degree raster scans were performed consisting of 37 high-resolution line scans that were repeated three times by one examiner. The Early Treatment of Diabetic Retinopathy Study (ETDRS) 9 region map was used for quantitative evaluation. We obtained Coefficients of variation (COV). Early Treatment of Diabetic Retinopathy Study (ETDRS) 9 region map used for quantitative measurement.

RESULTS Mean foveal thickness was 394.13 +/- 179.49. Mean retinal thickness in the ETDRS area 1 was 415.15 +/- 152.69. COVs ranged from 0.31% to 0.78%. Mean COV was 0.41+/-0.18%. Lowest COV (0.31%) was found for the ETDRS area 5. Highest COV (0.78%) was found for the central foveal thickness values. COV of area 5 was significantly lower compared with the COV of CPT and the COV of areas 1, 2,7, 8, 9 (P range: <0.01-0.028). Mean difference between measurement 1 and 2, measurement 1 and 3, and measurement 2 and 3 for all ETDRS areas was respectively 0.514, 0.515, and 0.531. No difference between the mean COV of each ETDRS area was found according to the anatomic location of uveitis.

DISCUSSION In inflammatory macular edema an excellent reproducibility of retinal thickness measurement is essential to monitor the progression of the disease and the results of the treatment during the follow-up. The present study shows that Spectralis OCT provides high intraobserver reproducibility of retinal thickness in uveitic macular edema. The reproducibility did not appear to be affected by the presence of cystoid abnormalities and inflammatory macular edema was found to not influence the OCT measurement accuracy. The reproducibility of retinal thickness measurement in uveitic macular edema is not influenced by the different location of uveitis (anterior, intermediate, posterior, diffuse).

CONCLUSIONS As far as we know this is the first study on the reproducibility of retinal thickness measurements in uveitic macular edema using Spectralis OCT. Our results show an excellent intraobserver reproducibility by the Spectralis OCT which provides accurate measurement in the foveolar center-point and in all ETDRS macular areas.