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J. P. Velazquez-Martin, G. Ortiz-Nieva; Keratectasia Parameters Changes With Pentacam After Laser in situ keratomileusis. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2929.
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Laser in situ keratomileusis (LASIK) for myopia is the laser refractive surgery most frecuently done and the one with the most significant post procedure keratectasia rate. The purpose of this study was to compare pre and post LASIK keratectasia indexes (8mm zone) by Scheimplugg imagging (Pentacam, Oculus).
In a prospective observational case-series study, 100 consecutive myopic patients having LASIK refractive surgery were examined with the Pentacam preoperatively and 3 months postoperatively. Readings of the Index of Surface Variability (ISV), Index of vertical asymmetry (IVA), Keratoconus Index (KI), Central Keratoconus Index (CKI), Index of Height Asymmetry (IHA), Index of Height Decentration (IHD), Minimum Sagital Curvature (Rmin) and Aberration Coefficient (ABR) from the central 8mm were collected and used in the analyses. All patients had an adecuate postoperatory and no clinical signs of ectasia.
Statistically significant changes were found on ISV, IHD and ABR, wich resemble keratoconus type of ectasia. The rest of the parameters did tend to ectasia, but this was found no statistically significant.
LASIK surgery for myopia tends to decompensate the cornea and therefore all the keratectasia parameters measured by Pentacam. Its importat to say that all of our patients were without clinical signs and had good visual acuity (>20/30) but most of them had at least one index of suspicion of ectasia. Further analysis is being held to try to identify wich parameter is of the most importance to detect early signs of ectasia and possibly redefine screening criteria.
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