Ophthalmic Applications of Ultrahigh Speed OCT Using VCSEL Light Source Technology

Abstract

 

Purpose:

 

To demonstrate the performance of swept source OCT systems utilizing vertical cavity surface emitting laser (VCSEL) technology for in vivo high speed anterior segment and retinal imaging of the eye.

 

Methods:

 

An ultrahigh speed swept source OCT instrument operating at 1050nm using new VCSEL light source technology was developed. The MEMS tunable VCSEL enables variable spectral tuning range, long coherence length, and tunable high sweeping rate (100kHz-700kHz axial scan rate), which allows integration of multiple ophthalmic applications in one compact instrument. The multimodal prototype OCT system was used to image retina and anterior segment in normal subjects and in patients. The operational modes of the device included: high speed high resolution retinal imaging, high speed anterior segment imaging and long depth range full eye imaging. We optimized 2-D and 3-D scanning protocols for each operational mode of the system.

 

Results:

 

We obtained high-resolution, wide field volumetric OCT retinal tomograms while operating at an effective imaging speed up to 700,000 axial scans per second. Increased light penetration at 1050 nm enabled visualization of choroidal vasculature. Comprehensive large scale volumetric data sets containing anterior segment structures from the cornea to the posterior surface of the crystalline lens were acquired. Adjustable VCSEL tuning range and sweep speed made it possible to achieve extremely long imaging depth range of >40mm, resulting in the first in vivo 3-D OCT imaging spanning the depth of the entire eye to enable measurement of axial eye length.

 

Conclusions:

 

VCSEL application in OCT enables enhanced functionality of ophthalmic imaging. Ability to change the sweep characteristics with the VCSEL allows an integrated and multi-purpose OCT instrument to provide comprehensive quantitative information of both anterior and posterior segments of the eye. Long imaging range enables full eye length measurement. These results suggest that VCSEL technology may be attractive for next generation ophthalmic OCT instruments.  

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior segment • retina