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J. M. Wanek, M. Mori, M. Shahidi; Wavefront Aberration Measurement and Correction With Adaptive Optics in the Presence of Increased Light Scatter. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4263.
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© ARVO (1962-2015); The Authors (2016-present)
Improvement in retinal image resolution has been demonstrated by recently developed wavefront sensing and adaptive optics (AO) technologies. Since in older and/or retinal-diseased subjects wavefront aberrations and intraocular light scatter are elevated, the performance of an AO retinal section imaging system in the presence of increased light scatter was evaluated and the effect of increased high order wavefront aberrations on image resolution was investigated.
Imaging was performed in a model eye using a bench-top prototype AO retinal section imaging system. The system incorporated a Shack-Hartmann (SH) wavefront sensor and a deformable mirror (DM) to measure and correct wavefront aberrations. Retinal section images were generated by projecting a laser line at an oblique angle on a model retina and imaging the reflected/scattered light from the anterior and posterior surfaces. Wavefront aberrations were measured for a 6 mm pupil by the root mean square (RMS) of the Zernike coefficients determined using a least-squares method. Image resolution was estimated by the full width at half maximum (FWHM) of a Lorentzian curve fitted to the anterior intensity profile derived from the section image. Light scatter was incrementally elevated by increasing the number of light scattering particles in the lens of the model eye. After AO correction, image resolution was measured while systematically varying the level and type of high order aberrations with the DM.
Without light scatter, wavefront aberrations were minimized and image resolution was improved with AO correction. The total RMS wavefront error measured before and after AO correction was 0.44 ± 0.02 and 0.07± 0.01 microns (N = 11), respectively. The presence of increased light scatter reduced the signal to noise ratio of the SH images, but did not influence centroid detection and wavefront aberration measurements. Under increased light scatter conditions and with AO correction, wavefront error was effectively minimized resulting in a 2-fold reduction in the FWHM of the anterior laser line profile. Induced high order coma and spherical aberrations after AO correction significantly reduced image resolution.
Under increased light scatter conditions, high order wavefront aberrations were effectively minimized with AO and image resolution was improved in the model eye, suggesting that AO systems can potentially improve image resolution in subjects with elevated intraocular light scatter.
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