Young Joo Shin,1 Sang Mok Lee,2 Jin Choi,3 Eun Ryung Han,4 Dong Hae Kim4

1Hallym University Gangnam Sacred Heart Hospital 2 3The Armed Forces Medical Command

3Department of Ophthalmology, Seoul National University College of Medicine

4Myung Dong St. Mary’s Eye Center

• We conducted a retrospective analysis of laser refractive corneal surgery including LASIK and LASEK to evaluate the risk factors for retreatment using survival analysis for long-term results.

• Study Population – This study was a retrospective analysis of the records of all

patients who underwent laser refractive corneal surgery from 1999 to 2008.

– Routine preoperative : UCVA , BSCVA, MR and CR, refraction, slit-lamp biomicroscope, IOP, corneal topography, keratometry, corneal thickness, indirect ophthalmoscopy and a screening visual field test

– Postoperative refractive status (SE) and IOP were evaluated at 1 and 3 month postoperatively.

– In the cases of retreatment, pre-operative ophthalmic examination includes SE, keratometry, IOP and corneal thickness. SE and IOP were evaluated at 1 and 3 month post-reoperatively

– Subjects were divided into three groups by level of refractive correction. • Group 1 had low myopia (SE < -3.00D) • group2 moderate myopia (-3.00D ≤ SE <-6.00D) • group 3 high myopia (SE ≤ -6.00D)

• Surgical Technique– Surgery was performed under topical anesthesia (3 drops of

proparacaine 0.5% at 5-minute intervals). Both the initial and retreatment procedures were performed by the same experienced surgeon (D. H. K).

• Retreatment technique– Retreatment was performed in patients who had residual refractive

error of more than -1.00D (SE) and complain of subjective symptoms after laser refractive corneal surgery. Every patient had at least two successive refractions at 1-month intervals before re-treatment to ensure stable refraction. LASIK treatment was performed when the estimated residual stromal tissue after laser ablation was 250 mm or more.

– Surgical procedures for retreatment were done as follows. All re-treatments in patients who underwent LASIK and need retreatment were done by lifting the flap. All re-treatments in patients who underwent LASEK and need retreatment were done by the same as primary LASEK procedure.

– Patients were seen on the first postoperative day, and then at 1, 3, 6, 12 months and every year after refractive surgery, and all measurements recorded.

• The mean age at surgery: 28.4 ± 6.3 years, (18 to 54 years).

• M:F = 2137 eyes:7164 eyes. • Mean SE : -2.99 ± 1.44 D. • SE

– in men (-2.98 ± 1.51 D) = women (-2.98 ± 1.42 D; p = 0.691, t-test).

– LASIK (-2.94 ± 1.39 D) < LASEK (-3.68 ± 1.61 D; p < 0.000, t-test).

• no relationship – between surgical procedure and gender (p = 0.074, Chi square

test) – between laser type and surgical procedure (p = 0.331, Chi

square test). • The number of patients who underwent retreatment: 136

(1.5%).

• Kaplan-Meier survival analysis

the rate of retreatment in the Technolas group was significantly higher than that in the VISX group (p < 0.0001, Mantel-Cox log rank test)

the rate of retreatment in the high myopic group (group 3: > -6D) was significantly higher than that in the low myopic group (p < 0.0001, Mantel-Cox log rank test)

• Kaplan-Meier survival analysis

the rate of retreatment in LASEK group was significantly higher than that in LASIK group (p = 0.006, Mantel-Cox log rank test)

the rate of retreatment in male was significantly higher than that in female (p = 0.046, Mantel-Cox log rank test)

• Cox regression analysis showed – only the rate of retreatment in Technolas group and

high myopic group was significantly higher (p < 0.0001 and p < 0.0001, respectively),

– not in male and in LASEK (p = 0.521 and 0.749, respectively)

The survival curve in right eye was not different from that in left eye (p = 0.731, Mantel-Cox log rank tes

Kaplan-Meier survival plots of the three groups for eyes not requiring retreatment after corneal refractive surgery. Their survival curves were not significantly different (p = 0.202, Mantel-Cox log rank test).

• SEs of patients who underwent LASEK were not different compared to LASIK (p = 0.125, Mann-Whitney test) and SEs of patient treated with Technolas was better compared to VISX (p < 0.0001, Mann-Whitney test) immediately after retreatments.

• Three months after retreatment, SEs in patients who underwent LASIK (-0.54 ± 0.63 D) were more targeted compared to LASEK (-1.05 ± 0.51 D; p = 0.001, Mann-Whitney test) and SEs in patients treated with Technolas (-0.48 ± 0.52 D) were better compared to VISX (-1.10 ± 0.72 D; p < 0.0001, Mann-Whitney test).

• Corneal thickness increased after first corneal laser refractive surgery (Table 1). Real remnant corneal thickness (457.75 ± 29.91) was thicker compared predicted corneal thickness (436.79 ± 28.10) (p = 0.000, Mann-Whitney test).

Total LASIK LASEK Technolas VISXInterval btw primary surgery and retreatment

18.11 ± 14.27 17.58 ± 14.56 20.24 ± 13.1 15.56 ± 13.26 24.44 ± 14.87

preopSE (D) -6.259 ± 2.16 -5.98 ± 2.16 -7.48 ± 1.72 -5.58 ± 1.89 -8.08 ± 1.72Mean K (D) 43.71 ± 1.35 43.61 ± 1.35 44.05 ± 1.33 46.55 ± 1.24 43.52 ± 1.60IOP (mmHg) 16.16 ± 2.79 16.37 ± 2.89 15.35 ± 2.27 16.66 ± 2.72 14.81 ± 2.59Pachymetry (µm) 525.20 ± 27.60 533.15 ± 23.49 491.70 ± 15.30 531.88 ± 24.87 507.32 ± 26.38

Corneal ablation during operation (µm)

88.41 ± 17.38 89.05 ± 18.51 85.52 ± 11.77 90.21 ± 17.34 83.58 ± 16.81

Postop 1 monthSE (D) -0.87 ± 0.61 -0.91 ± 0.56 -0.75 ± 0.78 -0.91 ± 0.56 -0.79 ± 0.73IOP (mmHg) 11.73 ± 3.68 11.86 ± 3.88 11.21 ± 2.78 12.21 ± 3.90 10.48 ± 2.75Mean K (D) 39.52 ± 2.13 39.69 ± 2.17 38.94 ± 1.91 40.09 ± 1.92 38.08 ± 1.99Postop 3 monthsSE (D) -1.67 ± 0.72 -1.06 ± 0.73 -1.58 ± 0.54 -1.00 ± 0.71 -1.61 ± 0.58IOP (mmHg) 9.92 ± 2.30 9.83 ± 2.33 10. 30 ± 2.15 10.06 ± 2.27 9.52 ± 2.35Retreatment (µm)SE (D) -1.17 ± 0.722 -1.12 ± 0.77 -1.43 ± 0.41 -1.12 ± 0.69 -1.34 ± 0.78IOP (mmHg) 10.78 ± 2.22 10.99 ± 2.14 10.00 ± 2.41 10.98 ± 2.17 10.26 ± 2.31Mean K (D) 39.78 ± 1.59 39.80 ± 1.70 39.70 ± 1.09 40.17 ± 1.45 38.76 ± 1.53Real CT by ultrasound pachymetry (µm)

457.75 ± 29.91 465.64 ± 27.35 424.83 ± 12.22 463.98 ± 29.74 441.07 ± 23.32

Corneal ablation during retreatment (um)

22.76 ± 6.50 22.49 ± 6.43 24.17 ± 6.76 21.43 ± 5.49 26.32 ± 7.56

Post-reop 1 monthSE (D) -0.47 ± 0.62 -0.43 ± 0.57 -0.70 ± 0.78 -0.39 ± 0.51 -0.71 ± 0.79IOP (mmHg) 10.54 ± 2.61 10.88 ± 2.60 9.22 ± 2.26 11.16 ± 2.27 8.90 ± 2.80Post-reop 3 monthSE (D) -0.65 ± 0.64 -0.54 ± 0.63 -1.05 ± 0.51 -0.48 ± 0.52 -1.10 ± 0.72IOP (mmHg) 9.69 ± 2.20 9.53 ± 2.02 10.43 ± 2.71 9.86 ± 2.21 9.27 ± 2.19Predeicted CT (preop CT-ablation during operation

436.79 ± 28.10 444.10 ± 25.42 406.17 ± 14.68 441.66 ± 27.11 423.74 ± 26.55

Real CT at reoperation – predicted CT

20.97 ± 11.01 21.54 ± 11.36 18.65 ± 9.34 22.31 ± 10.70 17.32 ± 11.21

• Higher spherical equivalent, and excimer laser system was found to be a predictor of retreatment after laser corneal refractive surgery. Retreatment was safe and effective for correcting undercorrection and regression.