Abstract
Purpose: :
The ability to measure multiple points in depth simultaneously or at least near simultaneously is one of the inherent advantages of a method like OCT. While the advent of commercially available ophthalmic spectral domain OCT systems has made it possible to capture large amounts of data quickly, for interpretation the resulting images are usually displayed in either en face or cross sectional planes. It has previously been shown that the combination of multiple delay lines in both the reference and object arms of an interferometer may be used as a multiple depths en face OCT system. We demonstrate that it is possible to use this novel imaging system to simultaneously capture multiple en face images of the retina at different depths in vivo.
Methods: :
A novel combined OCT/SLO system (at 1050nm) was assembled that used multiple recirculating paths to enable simultaneous en face OCT images at multiple depths. The system utilized a galvanometer scanner to produce a 500 x 500 pixel SLO image (10 degree field) at two frames per second. Simultaneous to this, multiple plane OCT images are captured, all with pixel to pixel correspondence. The time for each pixel captured is 2 microseconds. The en face image separation is adjustable and for the purposes of the demonstration was set at 75 microns (in air). The axial resolution of each plane was between 30 and 50 microns across the eight planes captured (limited by the SLD light source used and bandwidth of the recirculation paths).
Conclusions: :
This is the first use of multiple recirculating paths in an ophthalmic OCT system. This method is scaleable to at least 0.2 microseconds pixel rate which could potentially provide images of 250 x 250 pixel images at 80 fps (using faster scanners and without taking into account SNR considerations).The simultaneous capture feature of this type of imaging may also be useful for differential measurements.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina