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N. Massamba, A. Basurto, B. Lamory, V. Parier, G. Soubrane; In Vivo Microscopy of Macular Soft Drusen Using Adaptive Optics. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3300.
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© ARVO (1962-2015); The Authors (2016-present)
The study objective was to explore the microscopic structure of soft macular drusen and surrounding retinal areas using an adaptive optics (AO) camera and compare the findings to those from standard clinical examinations.
18 patients of age between 65 and 85 and presenting soft macular drusen were recruited after an initial scanning laser ophthalmoscope (SLO) examination. We used an AO flood-illumination system to acquire high-resolution images of selected drusen areas. The AO device corrected ocular wavefront aberrations (OWAs) in closed-loop operation at 10 Hz, based on a 52-actuator electromagnetic deformable mirror and a 1024 lenslet Shack-Hartmann sensor (both Imagine Eyes, France). Simultaneously, a square 4° x 4° area at the eye fundus was flood-illuminated by a pulsed LED emitting at 850 nm and imaged through the deformable mirror onto a low-noise CCD camera (Roper Scientific, USA). Every acquisition provided a series of 20 consecutive reflectance images, out of which 10 were numerically averaged to produce an enhanced final image. The resulting AO images were analyzed in comparison with conventional infrared and auto-fluorescence fundus images and spectral optical coherence tomography scans.
The total amount of OWAs was reduced by the AO correction, from 0.99 µm RMS to 0.23 microns RMS on average. The soft drusen were visible in AO images as generally round areas delimited by a peripheral low-reflectance line. Their lateral dimensions ranged between 150 and 450 µm. Hyper reflective spots of size comprised between 2 and 15 µm were observed in many drusen inner areas. These bright spots were sometimes isolated, sometimes grouped into tight aggregates of 2 to 40 components. Cone photoreceptors were visible in areas between drusen in most AO images, however the mosaic image sharpness was significantly less uniform across the field than previously observed in younger, healthy retinas.
The microscopic structures observed in the AO images of soft drusen presented analogies with their previoulsy described anatomopathologic characteristics, which could not be identified using other in vivo imaging techniques. AO technology could help to refine the clinical classification of macular drusen and obtain deeper insight in their link with the development of different types of advanced AMD.
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