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| Relationship between preoperative keratometry, corneal flap diameter and thickness |
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| 作者：步绍翀 赵… 文章来源：天津医科大学眼科中心 点击数1554 更新时间：2005/5/26 9:25:34 文章录入：bushaochon 责任编辑：毛进 |
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| Purpose To evaluate the relationship between the preoperative keratometry and corneal flap diameter and thickness in laser in situ keratomileusis (LASIK) for moderate to high myopia.
Methods This study comprised 102 eyes of 59 patients having LASIK with the VISX 20/20 B Laser system and SCMD manual microkeratome. Visual Acuity, refractive error, central corneal thickness and keratometry (auto ref-keratometer and corneal topography) were measured preoperatively. The corneal flap vertical diameters were recorded intraoperatively. Visual outcome was followed postoperatively. Six months after LASIK, 37 eyes of 23 patients underwent confocal microscopic examination. The data were analyzed using a Pearson correlation coefficient, t test and ANVOA.
Results Preoperative myopic spherical equivalent (SE) refraction was -5.9681 ± 0.8233D (range -5.00D to -8.00D). Preoperative keratometry measured by autoref-keratometer (ARK-100, OSAKA, JAPAN) was 44.05 ± 1.29D (range 41.88D to 47.00D), preoperative keratometry measured by corneal topography (EYEMAP EH290, ALCON, AMERICA) was 43.11±1.58D (range 39.41 to 46.02D). The corneal flap diameter was 8.322±0.321mm (range 7.9mm to 9.0mm). There was significant correlation between preoperative keratometry measured by auto ref-keratometer and corneal flap diameter (p=0.000, r=0.586). There was also significant correlation between preoperative keratometry measured by topography and corneal flap diameter (p=0.000, r=0.500). When eyes were divided into 3 groups according to the preoperative keratometry ( <43.5D, ≥43.5D and ≤44.5D, >44.5D), a trend was noted that steeper cornea is correlated to larger corneal flap. The differences between the groups were statistically significant (p<0.05). The postoperative corneal flap thickness was 150.622μm±10.291 (range 130.0μm to 170.6μm). There was positive correlation between preoperative keratometry measured by autoref-keratometer and corneal flap thickness (p=0.016, r=0.393). There was positive correlation between preoperative keratometry measured by topography and corneal flap thickness (p=0.012, r=0.409).
Conclusions Steeper cornea are correlated to larger and thicker corneal flap in LASIK. According to our study, careful consideration of preoperative data (mean preoperative keratometric power, central corneal thickness, etc.) may improve the predictability of flap formation to reduce the risk of flap-related complications and enhance the efficacy of the refractive outcomes.
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