1. Comparison between Dynamic contour tonometry, Goldmann applanation tonometry and Ehlers-corrected Goldmann applanation tonometry in eyes after Laser In Situ Keratomileusis Noppamas Wongpitoonpiya,MD BMA General Hospital, Bangkok, Thailand The author has no financial interest in the subject matter of this poster

2. Purpose To compare intraocular pressure measurement using Goldmann Applanation Tonometry (GAT), Dynamic Contour Tonometry (DCT) and Ehlers-corrected GAT in eyes undergoing first time Laser In Situ Keratomileusis (LASIK) for correction of myopia

3. Methods Central Corneal Thickness (CCT) and IOP were measured in 88 eyes of 44 patients before and 4 week after LASIK. IOP measurement was performed by GAT and DCT sequentially 3 minutes apart. The Ehlers correction factor was applied on the GAT IOP measurement to calculate Ehlers-corrected GAT IOP.

4. Methods Pearson correlation was used to evaluate the association between CCT and IOP measured by GAT and DCT.

5. Results Mean preoperative IOP measured by GAT was 14.05 mmHg slightly lower compare with DCT IOP (16.27 mmHg) and Ehlers-corrected GAT (15.23 mmHg)

6. Results Mean corneal ablation was 81.3 ± 23.3 micron. After LASIK, the mean GAT measurement dropped by –4.33 mmHg ± 2.7 (SD) and the mean IOP obtained by DCT dropped by -1.17 mmHg ± 1.80 (SD). Both GAT and DCT IOP decreased significantly after LASIK (P<0.001) but the correlation between IOP changes and CCT reduction were stronger in IOP by GAT.

7. Results In contrast to IOP measured by GAT and DCT, mean Ehlers-corrected GAT was slightly higher after LASIK. No significant correlation of CCT changes and Ehlers- corrected GAT was found in this study (P=0.90).

8. Comparison of IOP measured by GAT pre & post op

9. Comparison of IOP measured by DCT pre & post op

10. Comparison of Ehlers-corrected GAT IOP pre & post op

11. Conclusion Corneal thickness alteration after LASIK affected IOP measurement by both GAT and DCT. Ehlers-corrected GAT changes were not correlated with CCT reduction after LASIK.