Purchase this article with an account.
K. A. Avila-Ocampo, J. P. Velazquez-Martin; Anterior Segment and Posterior Cornea Changes by Pentacam Pre and Post Laser Refractive Surgery. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5095.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Laser in situ keratomileusis (LASIK) for myopia is the most common type of laser refractive surgery and the one with the most significant post procedure keratectasia rate. It has been proposed that posterior cornea might be the first indicator of an early keratectasia. The purpose of this study was to compare pre and post LASIK anterior segment and posterior cornea changes in an uncomplicated postoperatory, by Scheimpflug imaging (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 corneal volume (CV), anterior chamber volume (ACV), anterior chamber depth (ACD), iris-cornea angle (ICA), pupil diameter (PD), KPD factor (relation between anterior and posterior corneal powers), as well as posterior cornea keratometry values (KV) and minimum sagital curvature (Rmin) were collected and used in the analyses. All patients had an adecuate postoperatory and no clinical signs of ectasia.
No statistically significant changes were found on the global measurements of the posterior cornea (KV and Rmin); interestingly, deeper ablations and 90 µ microkeratome plaque presented greater changes, than superficial ablations and 130 µ plaque, and this were found statistically significant. On the anterior segment results globally, only PD and KPD were found statistically significant. As with the posterior cornea, ACV, ACD, ICA presented greater changes with deeper ablations and 90 µ plaque, and it was found statistically significant.
Even though LASIK is a refractive surgery performed only on the anterior cornea, there are changes in the posterior cornea and even more interestingly, on the anterior chamber. We are only beginning to understand how LASIK surgery can alter deeper structures and functions. Some of the anterior chamber changes can be related to a posterior protrusion of the posterior cornea, like ACV, ACD and ICA. This results correlate with our previous studies which indicate that deeper ablations and 90m plaque tend to decompensate the cornea. It is important to say that all of our patients were without clinical signs and had good visual acuity (>20/30). Further analysis is being held to try to identify which parameter is of the most importance to detect early signs of ectasia and possibly redefine screening criteria.
This PDF is available to Subscribers Only