Abstract
Purpose: :
To compare the imaging capabilities for different OCT imaging wavelengths in healthy subjects as well as retinal pathologies in respect to contrast and, and depth penetration.
Methods: :
Three-dimensional volumes were acquired with two different spectrometer based frequency-domain OCT systems: A custom designed OCT system, utilizing a CMOS InGaAs camera with 47.000 A-scans per second and a light source with 70 nm bandwidth, centered at 1060 nm; and a commercial OCT system, based on a CCD detector with 20.000 A-scans per second, 50 nm bandwidth, centered at 830 nm.
Results: :
OCT at 1060 nm allows for better visualization of choroidal vessels due to reduced scattering, while still enabling comparable details in intraretinal layers. In less pigmented cases the choroidal-scleral interface was visualized, enabling quantification of the choroidal thickness, which might be useful in glaucoma diagnosis. The enhanced visualization of the choroid might have diagnostic potential in diseases with choroidal neovascularization, e.g. AMD and DR. Imaging with 1060 nm also leads to better results in cases of turbid media, e.g. cataract.The speed advantage of a factor of 2.5 leads to less distorted tomograms which are virtually free of motion artifacts. Wide field imaging is demonstrated with sufficient resolution to visualize retinal and choroidal vasculature. In addition, OCT at 1060 nm can be used for physiological measurements using optophysiology, because it prevents pre-stimulation because of its invisibility to the human eye.
Conclusions: :
High speed imaging at the alternative wavelength of 1060 nm might be feasible for use in clinics, complementing OCT at the standard wavelength of 800 nm.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina • choroid