Dual optical coherence tomography and microscopy for characterization of cystinosis in the cornea

Abstract

Purpose : We investigate the feasibility of dual imaging with optical coherence tomography (OCT) and Gabor-Domain Optical Coherence Microscopy (GDOCM) to simultaneously visualize corneal morphology in three dimensions and resolve cellular features and cystine crystals in a knock-out (KO) mouse model of cystinosis, a rare childhood lysosomal storage disorder. Mutations in the CTNS locus in cystinosis cause corneal cystine accumulation and retinopathy that results in photophobia and visual deficits in patients.

Methods : Imaging of wild-type (WT) and KO CTNS mice were conducted with the novel dual-mode OCX imaging system. This model utilizes CRISPR/Cas9 to completely disrupt the CTNS gene. After excision, the eyes were stored in PBS and imaged within 24 hours. Volumetric GDOCM images with 1.4 mm x 1.4 mm field of view and 2-micron isotropic resolution over the entire corneal thickness were collected around the center of each cornea, as well as OCT images with 10 mm x 10 mm field of view and 13.5-micron lateral resolution. Due to the curvature of the cornea, cystine crystals affecting a particular corneal layer cannot be viewed in a single en face image; the 3D images were processed with a custom automated 3D flattening algorithm to present the view of the cystine crystals in a single en face image, which can be compared to the corresponding view obtained in wild type.

Results : High-resolution 3D OCX images of the cornea were collected, as shown in Fig. 1. In CTNS KO mice, crystals were visible in the GDOCM images. After applying an automated 3D flattening procedure, the crystals were visualized in a single en face view, as shown in Fig. 2.

Conclusions : OCX was used to image and evaluate corneas from wild type and KO CTNS mouse specimens. The OCT modality provided an overview of the overall corneal morphology, while GDOCM was shown to image all corneal layers across a large field of view with cellular resolution. A custom 3D flattening algorithm was applied to each cornea to produce an en face view of the cystine crystals.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

(a) Experimental OCX setup for dual GDOCM and OCT imaging of excised mouse eyes. (b) Detail of the noncontact imaging with 20 mm working distance. Representative 3D OCT (c) and GDOCM (d) images.

 

Flattened cornea en face view imaged with GDOCM over a field of view of 1.4 mm x 1.4 mm for WT (a) and KO CTNS Mouse (b), with ovals highlighting the cystine crystals.