Abstract
Purpose::
To evaluate patients with choroidal neovascularization (CNV) due to age-related macular degeneration (AMD) and compare the quantitative and qualitative characteristics of automated versus manual retinal measurement using the Stratus optical coherence tomography (OCT).
Methods::
Patients with CNV due to AMD prospectively underwent multiple OCT imaging using Stratus OCT Imaging (Carl Zeiss, Dublin, CA) with fast macular thickness map, linear cross hairs, and posterior pole scans over a 3-month period. The following measurements were analyzed: (automated) foveal thickness, (automated) central subfield, (manual) central retinal thickness, (manual) central lesion thickness, CNV thickness, pigment epithelial detachment (PED) thickness, CNV characteristics, signal strength, and number of correct retinal boundaries. Statistical analysis utilized concordance correlations, Bland Altman plots, and Chi-square or Fisher’s Exact tests.
Results::
209 OCT visits of 49 patients were analyzed. 67% of scans had signal strength of ≤7 (range, 2-10), while 52% had correct retinal boundaries of ≤4 (range, 0-6). Mean foveal thickness, central subfield, central retinal thickness, and central retinal lesion thickness were 312, 320, 277, and 471 µm, respectively. Foveal thickness had a mean difference of 8 µm and 34 µm relative to central subfield and central retinal thickness (p < 0.00005), respectively. Central subfield had a mean difference of 43 µm relative to central retinal thickness (p < 0.00005). Central retinal lesion thickness had a mean difference of 159, 151, and 193 µm from foveal thickness, central subfield, and central retinal thickness (p < 0.00005), respectively. Only 40% and 27% of foveal thickness and central subfield, respectively, lie within +/- 25 µm of central retinal thickness. Difference in measurements was lowest with correct retinal boundaries 6 and/or signal strength 10.
Conclusions::
Manual retinal thickness measurements differ significantly from those calculated by the current automated OCT software in patients with exudative AMD. We propose that manual measurements are superior to automated calculations in this population. Standardized terminology and measurement parameters are needed for ease of comparison across clinical studies. Furthermore, manual central retinal lesion thickness represents the true status of the retina and best quantifies retinal ‘activity’ in exudative AMD patients.
Keywords: choroid: neovascularization • age-related macular degeneration • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)