Abstract
Purpose: :
The combination of adaptive optics with a scanning laser ophthalmoscope has been shown previously to provide a non–invasive, cellular–scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. The use of new micro–deformable mirror (µDM) technology in an adaptive optics scanning laser ophthalmoscope (AOSLO) offers the potential of large aberration correction along with the capability of focusing through different layers of the living retina, all in a compact form factor.
Methods: :
Two µDM’s were used in a compact AOSLO system. One is a bimorph mirror (Aoptix, Inc.) with 37 elements and 15 µm stroke in a 10 mm aperture. The second is a MEMS mirror (Boston Micromachine, Inc) with 140 elements and 3 µm stroke in a 3 mm aperture. We used the bimorph for large–stroke, low–order aberration correction and the MEMS for low–stroke, high–order aberration correction. All optical components for this AOSLO were assembled onto a portable 2’x3’ table mounted on a moveable cart.
Results: :
In vivo retinal images of human subjects showed substantial resolution improvement with the bimorph µDM compensating the large–stroke, low–order aberrations. Furthermore, a significant signal–to–noise improvement of retinal images was observed with the addition of the MEMS µDM. The bimorph µDM with 15 µm stroke also provided the AOSLO system with the capability of focusing through different retinal layers within a 300 µm depth range.
Conclusions: :
We have demonstrated that multiple micro–deformable mirrors in an AOSLO system can effectively compensate both large, low–order and small, high–order aberrations in the human eye, and produce in vivo retinal images with nearly diffraction–limited resolution. Focusing through different layers of the retina is also made possible by the use of large–stroke micro–deformable mirrors. Furthermore, the small size of the µDM’s enables a compact optical design, making the AOSLO system a viable, portable, non–invasive, high–resolution imaging tool for clinical diagnostics.
Keywords: imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina