1. Simulated Experiments on IOL Power Calculation Using Anterior Segment OCT Dong Hyun Jo, M.D., 1,2 Mee Kum Kim, M.D., 1,2 Won Ryang Wee, M.D. 1,2 1 Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea, 2 Seoul Artificial Eye Center, Seoul National University Hospital Clinical Research Institute, Seoul, Korea Financial disclosure: All authors have no proprietary interest in methods described in this article.

2. Purpose To compare the method of calculating intraocular lens (IOL) power by anterior segment optical coherence tomography (AS-OCT) with the clinical history (Single-K) and Double-K methods

3. Methods Patients  who had undergone LASEK from July 1, 2009 to June 30, 2010 Preoperative and postoperative examinations  Best spectacle-corrected visual acuity  Intraocular pressure  Anterior and posterior segment examinations Slitlamp biomicroscopy Funduscopy Automated keratometry Anterior segement optical coherence tomography (AS-OCT) LASEK was performed using Visx Star S4 (VISX Inc., Santa Clara, CA).

4. Methods Methods of IOL power calculation: SRK/T formula  Double-K method: devised by Aramberri Preoperative keratometric value → anterior chamber depth (ACD) Postoperative keratometric value → the power of IOL  Single-K method: “Clinical history” method  AS-OCT method we utilized corneal height (C h ) as measured by AS-OCT in the IOL power calculation

5. Methods: AS-OCT method 1. A horizontal line was drawn to connect both ends of the anterior chamber angles 2. A vertical line was drawn from the posterior surface of the corneal vertex to fall on the horizontal line. 3. The length of the vertical line was designated as C h. 1 2, 3 ChCh

6. Methods Comparison of Ch according to myopic status before and after the refractive surgery  Low myopia (>-3 D)  Moderate myopia (≤-3 D, >-6 D)  High myopia (≤-6 D) Comparison of the results among 3 methods with each other

7. Results Demographic, Refractive, and Keratometric Data : 73 eyes of 37 patients

8. Results Comparison Between Preoperative and Posoperative C h According to the Preoperative Myopic Status Ch pre = preoperative corneal height; Ch post = postoperative corneal height; Δ Ch = difference between preoperative and postoperative cornealheight *P < 0.05

9. Results Corneal Height Estimated Using the Different Methods The differences between values obtained with AS-OCT method and those obtained with the other 2 methods were statistically significant (P < 0.001 in both analyses).

10. Results Intraocular Lens Power Calculated Using the Different Methods P emme : IOL power to get emmetropia P emme obtained using AS-OCT method was higher than that obtained using the Single-K method lower than that obtained using the Double-K method. (P < 0.001 in both analyses)

11. Conclusions We demonstrated that C h as measured by AS-OCT could be utilized in IOL power calculation after corneal refractive surgery.