Abstract
Purpose: :
To quantify the outer nuclear layer (ONL)and intraretinal cystic spaces in patients with age-related macular degeneration (AMD) and determine if these parameters correlate with visual outcomes in patients that were treated with ranibizumab.
Methods: :
Images were obtained using the Radial Line protocol of 6 high-resolution B-scans on a single StratusOCT machine. Graded spaces included intraretinal cystic spaces when present, the ONL, and the whole neurosensory retina. Thickness and volume of each space was calculated for 9 standard ETDRS subfields and foveal center point. Univariate and multivariate analysis (GEE, SAS) was used to correlate OCT parameters with visual acuity at baseline, 6, and 9 months post-ranibizumab injection.
Results: :
Demographic characteristics of the population included 18% males with an average age of 78±6 years (mean±SD). Data here are reported for all 9 ETDRS subfields. Mean intraretinal cyst thickness and volume were 4.71±8.11µm and 0.35±1.13mm3, respectively. Mean ONL thickness and volume were 114.7±27.6µm and 3.24±0.78mm3 respectively. Mean ONL thickness and volume excluding cystic spaces were 110±24µm and 2.89±1.37mm3. Mean retinal thickness and volume were 265.4±33.2µm and 7.50±0.94mm3 respectively. In a univariate linear regression model using adjusted R2 values, ONL thickness was significantly correlated with logMAR visual acuity at baseline and 6 months (R2=0.11, p=0.04 at baseline and R2=0.12, p=0.05 at 6 months), though the correlations were small. ONL volume was also significantly correlated with logMAR visual acuity at baseline and 6 month time points (R2=0.11, p=0.04 at baseline and R2=0.12, p=0.05 at 6 months). Overall retinal thickness was also significantly correlated with visual acuity at baseline and 6 months (R2=0.19, p=0.02 at baseline and R2=0.14, p=0.05 at 6 months). None of the OCT parameters measuring overall retinal thickness, cystic spaces or ONL correlated significantly with 9 month visual acuity. In a multivariate linear regression analysis adjusting for ONL volume and retinal thickness no other variables were significantly correlated with visual acuity outcomes.
Conclusions: :
This study suggests that ONL thickness and volume are positively correlated with visual outcomes in patients receiving intravitreal ranibizumab for neovascular AMD. However, this correlation likely only accounts for a small component of those visual outcomes.
Keywords: age-related macular degeneration • imaging/image analysis: clinical • choroid: neovascularization