Abstract
Purpose:
To determine the association of retinal thickness measurements via non-invasive SD-OCT optical biopsy to histological measurements. We attempted to establish a correlation constant between SD-OCT measured retinal thickness and histological retinal thickness values.
Methods:
Eight anesthetized adult mice underwent SD-OCT scanning. The Bioptigen Spectral Domain Ophthalmic Imaging System was used to acquire right eye optical biopsies after standardizing images around the optic nerve head (ONH). All eyes received cryostat histological sectioning with H&E staining. 10x light microscopy was used to analyze every twentieth 10 µm thick tissue slice. Forty-eight SD-OCT and histological measurements were taken in six sites relative to the ONH location. Thickness measurements consisted of the total retinal thickness (TRT), and the following sublayers: photoreceptor outer and inner segment with external limiting membrane (OS/IS/ELM), outer nuclear layer (ONL), outer plexiform layer (OPL), inner nuclear layer (INL), inner plexiform layer/ganglion cell (IPL/GC), and retinal nerve fiber layer (RNFL). Thickness ratios between SD-OCT and histological measurements were used to determine correlation constants.
Results:
The mean (± SD) correlation constant for TRT between SD-OCT optical biopsies and 10x light microscopy of histological prepared sections was 0.96. Correlation constant values demonstrated that SD-OCT measurements were less than histological values for the OS/IS/ELM (0.91), OPL (0.87), INL (0.70), and IPL/GC (0.80) retinal layers. However, correlation constant values were thicker for the ONL (1.14), and RNFL (1.17) layers. When comparing sublayers with correlation constants greater than one (i.e. ONL and RNFL), there was a strong significant correlation (r2 = 0.98, p < 0.01) between SD-OCT and histology. Correlation analysis for constants less than one (i.e. OS/IS/ELM, OPL, INL, IPL/GC, and TRT) showed similar degree and strength of correlation (r2 = 0.99) and significance (p < 0.01).
Conclusions:
This investigation has established correlation constants between the in vivo SD-OCT technology and the traditional histological gold standard ex vivo method. This can provide a framework for the design of conversion factors for the translation of ex vivo data into in vivo information; thus enhancing the applicability of SD-OCT in vision science.
Keywords: 551 imaging/image analysis: non-clinical •
688 retina •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)