Novel and Semiautomated 360-Degree Gonioscopic Anterior Chamber Angle Imaging in Under 60 Seconds

Abstract

Obtaining slit-lamp gonioscopic images requires a high level of expertise and can be time consuming. The images typically are limited to 4 quadrants with limited resolution and can be affected by different lighting conditions. Our goal was to study the ability of the novel imaging system to quickly and easily document the full 360 degrees of the anterior chamber angle in a standardized manner. Cross-sectional cohort study. Eighty-four eyes from 50 subjects were included in this study, including 26 eyes from 17 normal participants and 58 eyes from 33 patients diagnosed with glaucoma. A newly introduced, commercially available gonioscope (GS-1, NIDEK Co, Gamagori, Japan) was utilized to perform semiautomated imaging of the full 360-degree iridocorneal angle on participants under an institutional review board-approved study. Topical proparacaine was administered to the eye to anesthetize the eye and imaging was completed using the 16-mirror, machine-attached gonioscopic lens coupled with lubricating ophthalmic gel ointment. The first step of the 2-step image acquisition process is analogous to manual gonioscopy, whereas the second step is performed by the instrument in an automated fashion. First, the instrument is manually moved forward by the operator to allow the machine-attached lens to make contact with the patient's corneal surface (time= 30 seconds). Second, the instrument automatically achieves fine focus on the iridocorneal angle and takes 16 sequential high-resolution photographs at multiple different focal planes (time= less than 30 seconds). Successful qualitative imaging of anterior chamber iridocorneal angle in normal and glaucomatous eyes including visualization of various implanted devices within angle before and after surgery in less than 1 minute per eye. In this pilot study, the full 360 degrees of iridocorneal angle of 84 eyes from 50 normal participants or glaucoma patients were successfully imaged using NIDEK GS-1 in under 60 seconds. All eyes were able to be imaged in 1 sitting, and we were able to image the full spectrum of angle from narrow/closed to fully open. The 360-degree views of the images were able to be displayed in 3 available formats (16-section display, a circular display, or a linear display). Successful imaging was also achieved of surgical devices and postsurgical conditions including CyPass, iStent, XEN, Baerveldt tube shunt, angle recession with iridodialysis, angle neovascularization, pigment dispersion, posttrabeculectomy sclerostomy and surgical iridectomy, and post-laser peripheral iridotomy. The newly introduced, semiautomated imaging system was able to document the full 360-degree iridocorneal angle views in normal and glaucoma eyes in less than 1 minute, which may allow longitudinal evaluation in a standardized manner. Furthermore, this system allows the ability to easily evaluate post-angle surgery changes and assess positions of implanted devices in the anterior chamber angle.