Abstract
Purpose :
Anterior segment optical coherence tomography angiography (AS-OCTA) provides a noninvasive method for visualization and diagnosis of corneal, scleral, and iris-related diseases. The ability to image these landmarks in a single scan enables the comprehensive evaluation of the vasculature as an alternative to invasive techniques such as fluorescein angiography. In this work, we demonstrate ultra-widefield single-shot OCTA of the anterior chamber.
Methods :
CIRRUSTM 6000 AngioPlex (ZEISS, Dublin, CA) was adapted using a pair of add-on external lenses to enable imaging of the anterior chamber of human eye (Figure 1A). The lenses were designed to provide telecentric illumination and collection of the OCT light on the front of the eye. An internal fixation target was integrated into the external lens prototype to aid in subject alignment and fixation (Figure 1B). Furthermore, a prototype scan pattern consisting of 700x500 A-scans (2 repetition per location for OCTA) over a field of view (FOV) of 21 mm ×15 mm (corresponding to transverse resolution of 30µm) was implemented. Ten normal subjects (N=10) were recruited under an IRB-approved clinical feasibility study and both eyes of each subject were scanned.
Results :
Figure 2 illustrates examples of vasculature visualization using the prototype lens and scan pattern. The top row shows the en face vasculature generated from full depth summation projection of the flow signal. The bottom row shows cross-sectional OCT B-scans. We observed that subjects with dark iris pigmentation showed less contrast in the vasculature image (6 out of 20 scans). Due to eye motion and absence of active tracking, 10 out of the 20 scans exhibited motion artifacts. The total acquisition time was found to be ~7 seconds per OCT volume.
Conclusions :
We demonstrated the single-shot ultra-widefield (up to 21x15mm) imaging of the vasculatures in the anterior segment of human eye using CIRRUS 6000 AngioPlex. This method can aid in the diagnosis and monitoring of tumors or developmental anomalies in the front of the eye.
This is a 2020 Imaging in the Eye Conference abstract.