Purpose
To investigate the applicability of a new dual-conjugate adaptive optics clinical prototype for wide-field high-resolution adaptive optics retinal imaging in healthy volunteers and patients with early stages of retinal disease.
Methods
A new design of a compact dual-conjugate adaptive optics clinical prototype has been built and used to image healthy volunteers and patients with early stages of retinal disease such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). The clinical prototype, based on the concept of dual-conjugate adaptive optics, employs five spatially separated retinal probe beacons, two magnetic deformable mirrors (DM) (ALPAO, Grenoble, France), and a multi-channel Shack-Hartmann wavefront sensor. Monochromatic aberrations are measured and corrected over a 6 mm pupil. The five probe beacons are generated using light at a wavelength of 830±10 nm from a superluminescent diode (Superlum, Cork, Ireland). A 52 actuator DM positioned in a plane conjugate to the pupil of the eye will apply an identical correction for all field-points in the field of view (FOV). A 97 actuator DM positioned in a plane conjugated to a plane inside the eye will contribute with partially individual corrections for the five angular directions and thus compensate for non-uniform (anisoplanatic) or field-dependent aberrations. Imaging is performed over a 7x7 deg FOV using a spectrally filtered Xenon flash at a wavelength of 575±10 nm.
Results
The dual-conjugate adaptive optics clinical prototype features a 7x7 degree FOV and allows retinal features down to 2 μm to be resolved. A narrow depth of field of approximately 9 µm in the retina enables tomographic imaging of separate retinal layers, such as the cone photoreceptor layer deep within the retina in AMD patients, and superficial retinal capillary layers in DR patients.
Conclusions
High resolution adaptive optics retinal imaging has enabled the vision research community to gain deeper insight into the development and progression of retinal diseases. We believe that the dual-conjugate adaptive optics clinical prototype has a future potential for clinical imaging with an impact particularly important for early diagnosis of retinal diseases, follow-up of treatment effects, and follow-up of disease progression.
Keywords: 550 imaging/image analysis: clinical •
585 macula/fovea •
648 photoreceptors