Quantitative Subanalysis of Intraretinal Cystoid Spaces and Outer Nuclear Layer using Optical Coherence Tomography in Neovascular Age-Related Macular Degeneration
Amir H Kashani 1,
Pearse A Keane 2,
Laurie Dustin 3,
Alexander C Walsh 2,
and
SriniVas R. Sadda 4*
1 Ophthalmology, Doheny Eye Institute, Los Angeles, California, United States
2 Ophthalmology, Doheny Retina Institute, Los Angeles, California, United States
3 Department of Preventive Medicine, Keck School of Medicine at University of Southern California, Los Angeles, California, United States
4 Department of Ophthalmology, Doheny Retina Institute, 1450 San Pablo Street - DEI 3610, Los Angeles, California, 90033, United States
* To whom correspondence should be addressed. E-mail: sadda{at}usc.edu.
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Abstract |
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Purpose:
To quantify intraretinal cystoid spaces (ICS) and the outer nuclear layer (ONL) using optical coherence tomography (OCT) in patients with neovascular age-related macular degeneration (AMD), and to investigate the correlation of these parameters with visual acuity.
Methods:
StratusOCT images from 53 patients receiving their initial treatment with intravitreal ranibizumab were collected. Images were analyzed using custom software (entitled OCTOR) that allows accurate manual segmentation of OCT B-scans, and provides thickness/volume measurements of ICS, ONL, neurosensory retina, pigment epithelial detachments (PEDs), subretinal fluid (SRF) and subretinal tissue (SRT). Univariate and multivariate analyses were used to correlate OCT parameters with best-corrected Snellen visual acuity. Reproducibility was assessed with weighted Kappa statistics and intraclass correlation coefficients.
Results:
A multivariate linear regression model with adjusted R2 values showed that ONL volume and SRT thickness significantly correlated with Snellen visual acuity (R2=0.15, p=0.002 and R2=0.19, p=0.001, respectively) with an overall model R2 of 0.34. Adjustment of ONL volume for ICS did not improve correlation with visual acuity, and ICS volume did not independently correlate with visual acuity. Weighted Kappa statistics showed excellent intergrader agreement for both ICS and ONL measurements.
Conclusions:
This study suggests that an increased total volume of the ONL is associated with decreased visual acuity in neovascular AMD, and that the total volume of ICS is not correlated with visual acuity. Although the correlations detected in this study are modest, quantitative subanalysis of OCT images may be of greater clinical relevance in the context of more advanced OCT technology.
Key Words:
age-related macular degeneration, optical coherence tomography, quantitative image analysis
