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S. M. Pantanelli, R. Sabesan, X. Cai, G. Yoon, H. B. Hindman; Contributions of Scatter and Ocular Aberration to Decrements in Visual Performance in Deep Anterior Lamellar Keratoplasty (DALK) and Descemet’s Stripping With Automated Endothelial Keratoplasty (DSAEK). Invest. Ophthalmol. Vis. Sci. 2010;51(13):6348.
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The goal of this study was to quantify the contributions of scatter and higher-order aberration in impairing best-corrected visual acuity (BCVA) and contrast sensitivity following DALK and DSAEK surgeries.
One DALK and one DSAEK eye from two different pseudophakic subjects were dilated and an artificial pupil was used to limit pupil size to 4.5 mm. Subjects were 15 and 13-months post-op, respectively. An adaptive optics (AO) system that corrects the ocular higher order aberration non-invasively was used to measure high contrast visual acuity (VA) and contrast sensitivity (CS). For each subject, VA and CS were measured with and without AO correction. Contrast sensitivity was measured at each of three spatial frequencies: 4, 8, and 12 cycles/degree. The optical benefit of higher-order aberration correction, as predicted by the modulation transfer function (MTF), was compared to the actual benefit, as observed during the CS experiment. The difference between these estimates the contribution of scatter to visual performance.
The DALK subject had 0.89 ± 0.10 and 0.57 ± 0.10 µm of higher-order root mean square aberration without and with AO correction, respectively, while the DSAEK subject had 0.72 ± 0.07 and 0.15 ± 0.04 µm pre- and post-correction. The DALK subject had a logMAR VA of 0.17 ± 0.04 and -0.10 ± 0.04 without and with AO correction, respectively, while the DSAEK subject had logMAR VA’s of 0.33 ± 0.03 and 0.10 ± 0.02. In the DSAEK subject, the decrement in performance not attributable to aberration was 43.8%.
The DALK subject had superior logMAR visual acuity pre- and post-AO correction compared to the DSAEK subject, despite greater higher-order aberrations and suboptimal AO correction with DALK. This suggests a lower contribution of scatter to decrements in VA with DALK. We propose that increased scatter with DSAEK results from donor-host corneal stromal interactions. More subjects are needed to further substantiate our hypothesis regarding the role of stromal-stromal interaction and scatter.
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