Imaging the fibrous structure of the ocular sclera with UHR-OCT

Abstract

Purpose : To image ex-vivo the fibrous structure of human ocular sclera with UHR-OCT and compare the images with histology, in order to determine changes in the scleral architectural organization associated with myopia.

Methods : Healthy and myopic human cadaver eyes were obtained from the Eye Bank of Canada and imaged 24-36h post mortem. The eyes were dissected and the vitreous and the retina removed to expose the sclera. Volumetric (1000 x 1000 x 2048) images of the sclera were acquired from ~1.5 mm x 1.5 mm areas of the sclera with a research grade UHR-OCT system that operates in the 800nmm spectral region and provides ~1 μm axial and ~1.5 μm lateral resolution in biological tissue. Cross-sectional and volumetric UHR-OCT images of the sclera were generated using Matlab and Labview. The UHR-OCT images of the human sclera were compared with cross-sectional H&E stained histopathology images that were analysed with bright field microscopy, as well as with transmission electron microscopy (TEM) from previously published studies (Komai and Ushiki, IOVS, 1991).

Results : UHR-OCT provides detailed information of the precise architectural organization of the sclera, the spatial arrangement and thickness of the scleral fibrilae. Figure 1A shows a volumetric UHR-OCT image of the human sclera, while the images in fig. 1B and 1C show enface UHR-OCT images acquired from two different locations of the posterolateral sclera. The superficial layer of the sclera reveals fibrous structure with random orientation of the collagen fibrilae, characteristic for the dense irregular connective tissue. The histological image (fig. 1D) demonstrates the fibroblasts interspersed in between the collagen fibrilae. For comparison of the precision of our UHR-OCT imaging method, Fig. 1E shows a high magnification transmission electron microscopy (TEM) enface image of the fibrous structure of the human sclera.

Conclusions : UHR-OCT is able to map the fibrous structure of the ocular sclera and detect changes in the structure associated with myopia. With some modifications, the UHR-OCT technology has the potential to be adapted for in-vivo imaging of the human healthy and myopic sclera.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Volumetric (A) and enface (B, C) UHR-OCT images of the human sclera acquired ex-vivo. H&E stained histological cross-section of the human sclera, original magnification 63X (D). High magnification TEM enface image (E) of the fibrous structure of the human sclera (Komai and Ushiki, IOVS, 1991).