Transcript LLASK
Changes of Axial Length After LASIK Surgery: A 3-Year Follow-Up Study Yoshinori Nakai, Osamu Hieda, and Shigeru Kinoshita Department of Ophthalmology Kyoto Prefectural University of Medicine Kyoto, Japan Background Regression can occur after LASIK surgery even without obvious complications during or after the procedure. Corneal epithelium over-formation (change of thickness) Forward displacement of the posterior cornea Lens stiffening Axial length elongation? • • • • • Lohmann CP. Regression after LASIK for the treatment of myopia: the role of the corneal epithelium. Semin Ophthalmol. 1998;13:79-82. Spadea L. Role of the corneal epithelium in refractive changes following laser in situ keratomileusis for high myopia. J Refract Surg. 2000;16:133-9. Kozak I. Changes in central corneal thickness after laser in situ keratomileusis and photorefractive keratectomy. J Refract Surg. 2003;19:149-53. Ciolino JB. Changes in the posterior cornea after laser in situ keratomileusis and photorefractive keratectomy. J Cataract Refract Surg. 2006;32:1426-31. Seitz B. Posterior corneal curvature changes after myopic laser in situ keratomileusis. Ophthalmology. 2001;108:666-72; discussion 673. Purpose To investigate the changes of axial length and corneal curvature after LASIK surgery. Subjects • 544 eyes（286 cases: 147 males, 139 females）of Japanese patients who were followed up for 3 years postoperatively. • Mean patient age: 37.4 years（range: 20-72 years） Methods • Axial length was determined by ultrasound Amode (TOMEY) and IOL-Master® (Zeiss). • Corneal curvature was determined by ARK700A® (NIDEK). • A comparative study was then made between higher myopia（≤-6.0D）and low-moderate myopia（-6.0D<）. Mean of Preoperative DATA • • • • UCDVA: 0.05; CDVA: 1.3 Spherical Equivalent (S.E.): -6.0(±2.8)D Axial Length: 26.09(±1.3)mm Corneal Curvature: Kw42.8(±2.4)D; Ks44.1(±2.5)D; Kave.43.4(±2.4)D ≤-6.0D: 146 cases, 276 eyes A-mode: 133 cases, 254 eyes IOL-Master ®: 13 cases, 22 eyes -6.0D<: 140 cases, 268 eyes A-mode: 131 cases, 248 eyes IOL-Master ®: 9 cases, 20 eyes Examinations • Postoperative to 3-Years Postoperative UCDVA and CDVA Spherical Equivalent (S.E.) Axial Length Corneal Curvature (Kw, Ks, Kave.) • Correlation between Regression (Changes of 1-Year to 3Years Postoperative) and… Axial length elongation Changes of corneal curvature Patient age at the time of surgery Visual Acuity 10 1 1.35 1.28 1.44 1.30 1.35 1.05 1.46 1.26 1.36 1.01 1.45 1.26 1.35 0.94 ≤-6.0D >-6.0D 0.1 0.08 0.03 0.01 Spherical Equivalent (S.E.) （D） * * 2 * ** ** 0 PRE 1Y 2Y 3Y -2 -4 ≤-6.0D >-6.0D -6 -8 -10 * p<0.001 ** p<0.01 Axial Length (A-mode) （mm） * ** 29 28 27 26 <-6.0D 25 >-6.0D 24 23 22 PRE 1Y 2Y 3Y * p<0.01 ** p<0.05 Axial Length (IOL-Master®) ** ** 29 ** 28 27 26 ≤-6D 25 >-6D 24 23 22 PRE 1Y 2Y 3Y * p<0.01 ** p<0.05 Corneal Curvature ≤-6.0D （D） 46 ** * 44 44 42 42 * * * 40 ** * Kw Ks Ka 38 34 34 2Y 3Y * * Kw Ks Ka 38 36 1Y ** * 40 36 PRE >-6.0D （D） 46 PRE 1Y 2Y 3Y * p<0.01 ** p<0.05 1- and 3-Year Postoperative Changes ≤-6.0D Post 1Y Post 3Y -6.0D< Post 1Y Post 3Y S.E. -0.44(±0.76) -0.60(±0.90) S.E. -0.13(±0.36) -0.19(±0.42) AL 26.84(±1.22) 26.84(±1.16) AL 25.44(±0.96) 25.48(±1.02) Kave. 38.55(±1.56) 38.67(±1.58) Kave 40.40(±1.57) 40.44(±1.61) P<0.01 P<0.05 Correlation with Regression (P value) ≤-6.0D P value -6.0D< P value AL 0.516 AL 0.078 Kave. <0.001 Kave 0.793 Y.O. 0.456 Y.O. 0.690 Summary • Regression had occurred by the end of the 3rd postoperative year. • Axial length had elongated approximately 0.1mm by the end of the 1st postoperative year. • A significant correlation was found between regression and changes of corneal curvature in cases of higher myopia (≤-6.0D). Conclusion • Not only changes of corneal curvature but also the elongation of Axial Length might have to be considered as the reason for regression after LASIK surgery. • The findings of this study might need to be compared to further investigations involving the measurement of more cases by IOLMaster®.