Wide field of view optical coherence tomography angiography

Abstract

Purpose : Images from recently introduced ultra-wide field of view (FOV) fundus cameras have shown that examining the peripheral regions of the retina may impact the assessment of severity of disease. In this study we increased the image area of the to date widest FOV OCT angiography scan on a commercial device by another 70%, while increasing the scanning depth from 3 mm to 6 mm in tissue and maintaining excellent image quality.

Methods : We modified a PLEX^® Elite 9000 (ZEISS, Dublin, CA) to image the human retina with an A-scan rate of up to 200 kHz and an imaging depth of 6 mm in tissue. To widen the FOV we designed an add-on lens that magnetically attaches to the ophthalmic lens of the device. The speed gain was used to maintain a dense lateral sampling over the field of view to 15.6 mm x 15.6 mm. Volumes were acquired in a single shot with a sampling of 800 x 800 x 2 A-scans (horizontal x vertical x B-scan repetitions) with a pixel separation of 19.5 μm.

Results : The imaging depth of 6 mm helped especially in myopic patients, where current OCT angiography devices typically struggle to fit the concave retina within the imaging window. So far we have successfully imaged patients with a refractive error of up to -10 D in a single shot. We captured 15.6 mm x 15.6 mm and 15 mm x 9 mm OCT angiography images of healthy and diseased eyes (Fig. 1), without the need for montaging multiple acquisitions. The higher A-scan rate allowed maintaining a dense lateral sampling and hence excellent image quality over the entire field of view.

Conclusions : We present the, to the best of our knowledge, widest field of view single-shot OCT angiography images to date. In the next step we will further broaden the field of view to up to 90 degree by the help of a newly designed wide angle add-on lens.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Fig 1: Single shot OCT angiography image of a a) healthy eye with 15.6 mm x 15.6 mm FOV, b) patient with retinal vein occlusion with 15 mm x 9 mm FOV