Abstract
Purpose: :
Retinal thickness measurements are of increasing importance in clinical practice and investigation of age-related macular degeneration (AMD). Automatically generated measurements of the retinal volume or the central retinal thickness between the retinal surface and the retinal pigment epithelium are based on correctly set threshold lines. The aim of this study was to compare the reliability of threshold algorithm lines of Stratus optical coherence tomography (OCT) and Cirrus OCT.
Methods: :
A consecutive series of patients aged more than 50 years with exudative age-related macular degeneration underwent Stratus OCT (retinal thickness program) and Cirrus OCT (Macular Cube 200x200) performed by the same examiner immediately one after the other. The fellow eye was also included when presenting with age-related macular degeneration. The scans of both examinations were compared concerning errors in retinal boundary line placement by the wilcoxon rank sum test. Paired sample T-Test was applied to give the correlations between quality of boundary line placement and distance visual acuity (VA) assessed with ETDRS charts.
Results: :
71 eyes of 50 patients with a mean age of 73 years, 68% females, 32% males were included.There was a wide range of disease activity: 9.8% with non exudative AMD, 25.4% fibrotic lesions, 21.1% naïve lesions, and 43.7% at various stages of treatment with antiangiogenetic substances. Errors in retinal boundary line placement were significantly (p=0.0001) more frequent in Stratus OCT (50.7%) than in Cirrus OCT (22.5%). Errors were significantly correlated to reduced distance acuity (p<0.0001) and significantly more frequent in fibrotic lesions concerning both examinations (p=0.02: Stratus OCT, p=0.002: Cirrus OCT
Conclusions: :
The Cirrus OCT provides due to the spectral domain technology a 2-fold resolution than Stratus OCT generated in a comparable amount of time. Due to this higher resolution the retinal surface and the retinal pigment epithelium can be identified more clearly resulting in a significantly lower rate of threshold algorithm failures. Morphologic changes of the retinal pigment epithelium due to exudative AMD are responsible for the remaining errors of boundary line placement.
Clinical Trial: :
www.clinicaltrials.gov NCT00568191
Keywords: age-related macular degeneration