Posterior corneal surface stability and anterior chamber depth measurement after laser-assisted keratomileusis

Session Details

Session Title: LASIK

Session Date/Time: Monday 12/09/2016 | 08:00-10:30

Paper Time: 09:54

Venue: Hall C3

First Author: : J.Costa PORTUGAL

Co Author(s): :    F. Neves   L. Figueiredo   C. Arede              

Abstract Details

Purpose:

To describe the posterior corneal surface (PCS) and the anterior chamber depth (ACD) variation after laser in situ keratomileusis (LASIK) relative to the estimated residual stromal bed thickness (RBT) and to the ablation percentage per total central corneal thickness (CCT), in patients with myopia and myopic astigmatism.

Setting:

Department of Ophthalmology, Centro Hospitalar de Vila Nova de Gaia/ Espinho, Portugal

Methods:

Retrospective, non-randomised study. The anterior and posterior best-fit sphere (BFS), ACD and CCT were measured in 130 myopic eyes (80 patients), using Orbscan before, one week and three months after LASIK. The patients were divided into groups based on estimated RBT (Group A - 38%, RBT 250 µm to 325 µm; Group B - 62%, RBT > 325 µm ) and based on the percentage of corneal ablation (Group 1 < 12% ablation - 46%; Group 2 > 12% ablation - 54%). Correlation between PCS and ACD variation, preoperative CCT, RBT and percentage of ablated corneal tissue was explored.

Results:

The mean posterior forward shifting was 0,08±0,13 mm and 0,05±0,04 mm at 1 week and 3 months, respectively (p<0.05). The ACD decreased by 0,02±0,06 mm (p<0,05) at 1 week and maintained unchanged until 3 months following LASIK. ACD and posterior BFS variation correlated with the percentage of ablated corneal tissue and RBT ( p<0,05). The mean posterior forward shifting was greater in Group A (p<0,05). A significant reduction of the ACD was found at 1 week in group B (p<0,05). Posterior BFS variation was greater in group 1 (p>0,05). Group 2 showed a significant reduction of the ACD (p<0,05).

Conclusions:

The posterior corneal displacement measured with Orbscan was significant and maintained until 3 months after LASIK and was more pronounced in patients with lower RBT and greater percentage of corneal ablation. The ACD measurement variation after LASIK was significant in patients with higher RBT and lower percentage of corneal ablation. In these eyes, the ACD was lower both at 1 week and 3 months when compared to the measurement before LASIK. Eyes with lower RBT and higher percentage of corneal ablation showed no significant changes in the ACD.

Financial Disclosure:

NONE