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P. M. Prahs, J. Kraus, K. Hufendiek, H. Helbig, W. Herrmann; Long Term Posterior Corneal Surface Changes After Epithelial Laser in situ Keratomileusis for the Correction of High Myopia. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5657.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the impact of epithelial laser in situ keratomileusis for the correction of high myopia on posterior corneal shape using anterior segment Scheimpflug imaging.
In a retrospective approach 24 eyes of 17 patients, mean age 37.2 ± 8.2 years (mean ± SD) that underwent uncomplicated epithelial laser in situ keratomileusis (epi-LASIK) for the correction of myopia with a spherical equivalent of more than six diopters have been included in the study (SEQ range -6 to -8 dpt). Anterior segment Scheimpflug photography using the Oculus Pentacam was performed at baseline and at a mean follow-up of 11.8 months (range 9 to 13) after refractive surgery. Using the pentacam data analysis software changes to baseline of best fit sphere radius, maximum elevation in the central 5mm of the posterior corneal surface, anterior chamber depth and anterior chamber volume have been evaluated. A paired t test was used to test for a difference between means before and after surgery.
Posterior surface best fit sphere radius, anterior chamber depth and anterior chamber volume changed from 6.53 mm ± 0.28 SD to 6.53 mm ± 0.29, 3.26 mm ± 0.36 to 3.17 mm ± 0.36 SD and 205 mm² ± 40 SD to 198 mm² ± 42 SD at the end of follow-up, respectively. No significant difference in BFS radius was detected. Difference maps for posterior surface elevation relative to best fit sphere were calculated. Maximum elevation difference in the central 5 mm were 6.3 µm +/- 2.9 SD. The magnitude of the detected difference was comparable to the spread of intersession repeated measurements.
A significant change in posterior corneal shape after epi-LASIK was not detected in this study. These findings suggest that surface ablation techniques up to a SEQ of 8 dpt are unlikely to change posterior corneal morphology indicating keratectasia.
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