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Purpose: To assess the relationship between measures of light distortion and retinal straylight in normal and post-LASIK subjects. Design: Cross-sectional, non-randomized, masked observational case series Setting: Clinica Oftalmologica Novovision, Madrid, Spain. Methods: Thirty eyes from 30 healthy subjects (mean age 33.9 ± 8.3 years old; mean spherical equivalent (MSE) −2.06 ± 1.40 D) and thirty six eyes from thirty six refractive surgery patients (mean age 36.1 ± 7.7 years old; mean preop MSE −3.43 ± 2.23 D) were examined with the Starlights and the C-Quant straylightmeter in a case-control study. Results: The age of both treated and control groups was not statistically different ( p > 0.05). Statistically significant differences between controls and post-LASIK eyes were found for luminous distortion index (LDI), but not for retinal straylight. Correlation analysis yielded significant correlation between retinal straylight Log(s) values and BCVA measures ( r = 0.379, p = 0.002). Control subjects showed significant correlation between MSE and retinal straylight Log(s) values ( r = -0.650, p < 0.001), while post-LASIK eyes showed a significant correlation between LDI and Log(s) values ( r = 0.338, p = 0.044) and between Log(s) values and BCVA ( r = 0.460, p = 0.005). Correlation between measures obtained by both methods was higher after LASIK than in control eyes, although values were quite scattered in any case. Conclusion: Light distortion phenomena and retinal straylight measures are correlated in both normal and postsurgical eyes. Both parameters are increased in LASIK subjects compared to control non-operated subjects. [ABSTRACT FROM AUTHOR]

Purpose: To describe and compare the stromal bed roughness obtained after laser in situ keratomileusis (LASIK) flap creation using a corneal femtosecond laser platform (iFS 150) and a "dual" femtosecond (FS) laser platform (LenSx). Methods: This ex vivo experimental study was conducted in an animal model using 12 freshly enucleated porcine eyes, six with each femtosecond laser. The standard laser treatment parameters were used for the experiment. After LASIK flap creation, the corneal stromal roughness was assessed using atomic force microscopy (AFM) in contact mode immersed in liquid. In each sample, surface measurements were obtained in 60 regions of six eyes per FS laser in 10 20 × 20-micron areas of the central corneal stroma at 512 × 512-point resolution. The surface roughness was measured and the root-mean-square (RMS) values of the roughness were obtained. Results: The mean RMS ± standard deviation values were 430 ± 150 nm for the corneal femtosecond laser platform and 370 ± 100 nm for the dual FS laser platform (P < 0.011). Conclusions: In this experimental study with AFM, we found smoother stromal beds after LASIK flap creation with LenSx compared to iFS 150 kHz. Further studies are needed to understand visual implications of the differences found. [ABSTRACT FROM AUTHOR]