Comparison of Corneal Power Measured by Different Methods after Refractive Surgery

Lee, Su Na; Choi, Si Hwan; Kim, Chang Sik

Abstract

PURPOSE: To compare the corneal power (K) measured by different methods in the patients who underwent photorefractive keratectomy (PRK) or laser in situ keratomilieusis (LASIK)
METHODS
Fifty-four patients who had undergone PRK or LASIK from December 1999 to December 2000 and followed for 3 months or longer were selected for this study. The corneal power was measured by five different methods in 35 eyes(18 patients) of PRK group and in 70 eyes (36 patients) of LASIK group: calculation method (C-K), hard contact lens method (H-K), autorefractokeratometer (A-K), manual keratometer (M-K) and topography (T-K).
RESULTS
Preoperative mean corneal power was 43.41+/-1.06 D in PRK group and 43.75+/-1.03 D in LASIK group. Postoperative corneal power in PRK group showed following Results: C-K, 40.94+/-1.51 D; H-K, 41.04+/-1.23 D; A-K, 41.18+/-1.29 D; M-K, 41.38+/-1.33 D; T-K, 41.67+/-1.26 D. In LASIK group, the results were: C-K, 38.64+/-2.25 D; H-K, 39.29+/-1.66 D; A-K, 39.53+/-1.61 D; M-K, 39.85+/-1.54 D; T-K, 40.36+/-1.26 D. The corneal power of calculation method was lowest in both groups. Each corneal power was not different statistically from the others in PRK group(p=0.16). However, C-K was significantly lower than A-K (p=0.02), M-K (p=0.00) or T-K (p=0.00) in LASIK group. Also, H-K or AK was lower than T-K statistically in LASIK group (p=0.00, p=0.02).
CONCLUSIONS
The corneal power was lowest when measured by calculation method after refractive surgery. In LASIK group, there were statistical differences among the corneal powers by each method.