Abstract
Clinically, gonioscopy is used to provide en face views of the ocular angle. The angle has been imaged with optical coherence tomography (OCT) through the corneoscleral limbus but is currently unable to image the angle from within the ocular anterior chamber. We developed a novel gonioscopic OCT system that images the angle circumferentially from inside the eye through a custom, radially symmetric, gonioscopic contact lens. We present, to our knowledge, the first 360° circumferential volumes (two normal subjects, two subjects with pathology) of peripheral iris and iridocorneal angle structures obtained via an internal approach not typically available in the clinic.
Highlights
The iridocorneal angle (ICA) is the circumferential region of the eye where the base of the iris joins the peripheral cornea
We developed a custom, radially symmetric gonioscopic contact lens coupled with Optical coherence tomography (OCT) to image the ICA which allowed for clinically accessible 360° imaging of the ICA within a single OCT volume
We have developed an optical system which images the entire 360° circumferential iridocorneal angle within a single volumetric acquisition using an internal approach
Summary
The iridocorneal angle (ICA) is the circumferential region of the eye where the base of the iris joins the peripheral cornea. In the Figure, a chief ray (red lines) propagates parallel to the optical axis (yellow dashed line) and reflects from one of the mirror facets (grey gradient) of the contact Using this cross-sectional model as a starting point for OCT gonioscopy, only a single radial location in the iridocorneal angle would be imaged. In the methods section we describe that we operate the final gonioscopic lens in a 2F configuration where we are imaging a point in the object plane two focal lengths away from the mirror (the focal plane of telecentric lenses) to the image plane (the iridocorneal angle and the surrounding tissue) which is another two focal lengths away This optical design concept is meant as an illustration of how a curved mirror focuses light and the design considerations that need to be made when transitioning from a flat surface to the curved surface basis utilized, it is not the final optical design. This paraboloid mirror approach is the design basis for the contact lens implemented for the circumferential GOCT system described in this work
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