80 degree field of view swept-source optical coherence tomography

Abstract

Purpose : The field of view (FOV) of commercially available optical coherence tomography (OCT) systems is typically limited to 30 degrees. And even the ability to capture images in the periphery to create montaged wide field images is still limited by the depth range of the OCT system. Images from recently introduced ultra-wide field of view fundus cameras have however shown that examining the peripheral regions of the retina may impact the assessment of severity of disease. In this study we demonstrate 80 degree OCT images without noticeable degradation of image quality in the periphery.

Methods : We modified a PLEX^® Elite 9000 (ZEISS, Dublin, CA) to image the human retina with an A-scan rate of 200 kHz and an imaging depth of 6 mm in tissue. To broaden the field of view, we designed an add-on lens, which magnetically attaches to the ophthalmic lens of the device and enables a field of view of 80 degree. To preserve excellent sensitivity over the entire field of view, peripheral aberrations were taken into account for the lens design. The add-on lens reduced the working distance of the device to 11.4 mm. Volumes of 1024 x 1024 A-scans as well as highly averaged B-scans (“Spotlight scans”) containing 2048 A-scans were acquired of normal as well as myopic eyes with up to -10 D refractive error. We compare these images with state of the art images from commercial systems, to illustrate the benefit of higher imaging speed, larger field of view and larger imaging depth.

Results : 80 degree FOV images of normal and myopic eyes were successfully obtained (Fig. 1). The system’s large imaging depth allowed us to capture the entire field of view with a single acquisition. Even the posterior segment of highly myopic eyes fit conveniently within the 6 mm deep imaging window. The signal strength and resolution showed no noticeable degradation in the periphery (Fig. 1 b)).

Conclusions : We demonstrated that large imaging depth is essential to capture such large field of views in a single shot. The careful design of wide angle scanning optics allowed for the first time to maintain excellent image quality over the entire field of view of 80 degree.

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

 

Figure 1. a) fundus projection of a 60 degree x 60 degree OCT volume acquisition; b) 80 degree HD spotlight scan