Changes in Posterior Corneal Surface After Laser Surface Ablation for Myopia

1. Changes in Posterior Corneal Surface After Laser Surface Ablation for Myopia Sun Woong Kim, M.D.1, Hae Jung Sun, M.D.1, Tae Im Kim, M.D.2, Eung Kweon Kim, M.D., Ph. D.2 Department of Ophthalmology, Soonchunhyang University Hospital, Bucheon, Korea 1, The Institute of Vision Research, Department of Ophthalmology, College of Medicine, Yonsei University, Seoul, Korea 2

2. The authors have no financial or proprietary interest in any materials or methods mentioned.

3. Purpose • To evaluate the changes in posterior corneal surface before and after laser surface ablation using a rotating Scheimpflug camera, the Pentacam (Oculus Inc, Wetzlar, Germany).

4. Methods • 30 myopic eyes (14 PRK, 16 LASEK) of 20 patients were evaluated preoperatively and postoperatively (1-6months) with the Pentacam • Main outcome measures • Posterior central corneal curvature change • the average in central 4mm zone in tangential curvature map • Posterior corneal elevation change • determined by subtracting the preoperative elevation data from the postoperative elevation data based on the maximum difference at the center of the difference map • BFS determined by preoperative measures • Anterior chamber depth (ACD) change • determined by subtracting the preoperative central ACD data from the postoperative central ACD data

5. Results Table 1. Patient demographics SE : Spherical equivalent

6. Results Table 2. Comparison of changes in posterior corneal measurements * P < 0.05 by paired t-test

7. Results A paradoxical decrease in ACD was seen after laser ablation. No significant differences were seen in the posterior curvature after laser ablation.

8. Results • The amount of forward shifting of posterior corneal surface had no correlation with residual corneal thickness or ablation depth (Pearson correlation, P > 0.05)

9. Conclusions • There was no significant protrusion in posterior corneal surface after laser surface ablation.