Handheld High Speed 500 kHz Swept Source OCT Device Using a Micro Scanning Mirror

Abstract

 

Purpose

 

The objective of this study is to design and demonstrate a compact handheld OCT device for disease screening to enable early detection before visual impairment. In addition, a portable and compact OCT device enables applications ranging from imaging in pediatric and trauma patients, to military medicine and in remote or undeveloped areas.

 

Methods

 

A compact handheld OCT patient interface shown in Fig. 1(A-B) was developed using a micro-electromechanical system (MEMs) scanning mirror. An iris camera, fixation target, and LCD screen was included in the device. Subjects were scanned sitting with the back of their head supported on a headrest. Orthogonal scanned OCT volumes were acquired in 1.45 seconds per volume using swept source OCT with a vertical-cavity surface-emitting laser (VCSEL) light source at 1050 nm wavelength and 500 kHz axial scan rate. The two orthogonal raster scans were then post-processed with custom motion correction registration software and merged to increase the signal to noise.

 

Results

 

Alignment of the device for proper OCT imaging typically required ~30 seconds with the aid of the iris camera and OCT preview scans. Adjusting the fixation target centers the OCT scan to a point between the macula and optic nerve head. Fig. 2(A) shows a 10mm x 10mm en face OCT fundus image from a registered volumetric OCT data set. Fig. 2(B-C) shows representative single cross sectional images. Fig. 2(D) shows a vertical cross section in the slow scan direction of the original volumetric data to compare the motion-corrected registered data.

 

Conclusions

 

A handheld OCT device has been built and tested to acquire wide-field OCT volumetric scans that when registered, generate a single motion-corrected OCT volumetric data set. Volumetric OCT provides both a motion corrected fundus image as well as comprehensive cross sectional information on the macula and optic nerve head.

 

 

Figure 1. (A) Side view of the handheld device in operation. (B) 3/4 view of the device. The spacing between holes is 1 inch.

 

 

Figure 2. (A) OCT fundus image from a 10mm x 10mm, 375x375 axial scan, motion corrected 3D OCT data set acquired by the handheld instrument. (B) Single horizontal cross section through the optic nerve head. (C) Single vertical cross section through the macula. (D) The same vertical section from the initial uncorrected data set showing the motion in the slow scan direction. All scale bars are 1 mm.

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)