Abstract
Purpose :
To image the fine structures of the human trabecular meshwork (TM) in vivo with gonioscopic Optical Coherence Tomography (OCT) imaging using a customized goniolens and a clinically available OCT device (Heidelberg Spectralis). The TM, located within the iridocorneal angle (ICA), is a target for many glaucoma treatments aimed at controlling intraocular pressure. However, variations in the structure of the TM tissue across normal subjects is poorly understood, including differences between normal and glaucoma patients due to limitations of in vivo imaging of this location.
Methods :
A novel custom two-mirror (59 and 63°) gonioscopy lens was manufactured to be index matched to the human cornea. An air-spaced doublet placed on the anterior surface of the goniolens body centered on each mirror is used to focus the light and provides an image plane at the approximate distance of the ICA structures, with a spot size of ~5µm. The subjects’ eye was anesthetized with Proparacaine Hydrochloride USP 0.5%. The goniolens was placed on the eye coupled with gonio-gel and aided by a 3D adjustable mount fixed to the head mount of the OCT device to provide additional stability. Dense OCT scans with minimum spacing oriented tangential to the iris and ICA were performed on 4 healthy subjects (22-72yrs). OCT volumes were segmented along the posterior uveal meshwork.
Results :
The TM was successfully imaged in all subjects. The custom goniolens improved the contrast of uveoscleral meshwork structures and corneoscleral meshwork revealing limbus parallel striations, not visible with previous goniolens designs. Transverse OCT images were constructed from a 50µm thick slab along the segmentation line, providing an enface image of the TM structures including corneoscleral beams, previously only imaged in vivo using custom adaptive optics systems.
Conclusions :
A commercial OCT device has successfully been used to image fine structures in vivo within the human trabecular meshwork with sufficient resolution to depict fine structural features.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.