patients with opacification of hydrophilic acrylic intraocular lens after cataract surgery. J Korean Ophthalmol Soc 2005;46:1281-90. 2. Lee JY, Joo KM, Kim SH. Late Opacification of hydrophilic acrylic intraocular lenses. J Korean Ophthalmol Soc 2002;43:2419-29. 3. Kim HG, Lee SH, Choi YJ. Late Postoperative opacification of the foldable hydrophilic acrylic intraocular lens, ACRL-160. J Korean Ophthalmol Soc 2003;44: 315-20. 4. Lee DH, Seo Y, Joo CK. Progressive opacification of hydrophilic acrylic intraocular lenses in diabetic patients. J Cataract Refract Surg 2002;28:1271-5. 5. Yu AK, Ng AS. Complications and clinical outcomes of intraocular lens exchange in patients with calcified hydrogel lenses. J Cataract Refract Surg 2002;28:1217-22. 6. Yu AK, Shek TW. Hydroxyapatite formation on implanted hydrogel intraocular lenses. Arch Ophthalmol 2001;119: 611-4. 7. Apple DJ, Werner L, Escobar-Gomez M, Pandey SK. Deposits on the optical surfaces of Hydroview intraocular lenses. J Cataract Refract Surg 2000;26:796-7. 8. Fernando GT, Crayford BB. Visually significant calcification of hydrogel intraocular lenses necessitating explantation. Clin Exp Ophthalmol 2000;28:280-6. 9. Jin GJC, Crandall AS, Jones JJ. Changing indications for and improving outcomes of intraocular lens exchange. Am J Ophthalmol 2005;140:688–94. 10. Carlson AN, Stewart WC, Tso PC. Intraocular lens complications requiring removal of exchange. Surv Ophthalmol 1998;42:417-40. 11. Mamalis N. Explantation of intraocular lenses. Curr Opin Ophthalmol 2000 Aug;11:289-95. 12. Raman S, Redmond R. Reasons for secondary surgical intervention after phacoemulsification with posterior chamber lens implantation. J Cataract Refract Surg 2003;29:513-7. 13. Gashau AJ, Anand A, Chawdhary S. Hydrophilic acrylic intraocular lens exchange: five-year experience. J Cataract Refract Surg 2006;32:1340-4. 14. Grading diabetic retinopathy from stereoscopic color fundus photographs: an extension of the modified Airlie House classification: ETDRS report number 10. Ophthalmology 1991;98:786-806. 15. Izak AM, WernerL, Pandey SK, Apple DJ. Calcification of modern foldable hydrogel intraocular lens design. Eye 2003;17:393-406. 16. Yu AK, Kwan KY, Chan DH, Fong DY. Clinical features SM Kim, et al. INTRAOCULAR LENS EXCHANGE of 46 eyes with calcified hydrogel intraocular lenses. J Cataract Refract Surg 2001;27:1596-606. 17. Frohn A, Dick HB, Augustin AJ, Grus FH. Late opacification of the foldable hydrophilic acrylic lens SC60B-OUV. Ophthalmology 2001;108:1999-2004. 18. Mamalis N. Hydrophilic acrylic intraocular lenses. J Cataract Refract Surg 2001;27:1339-40. 19. Werner L, Apple DJ, Kaskloglu M, Pandey SK. Dense opacification of the optical component of a hydrophilic acrylic intraocular lens; a clinicopathological analysis of 9 explanted lenses. J Cataract Refract Surg 2001;27:1485-92. 20. Apple DJ, Werner L, Pandery SK. Newly recognized complication of posterior chamber intraocular lenses. Arch Ophthalmol 2001;119:581-2. 21. Habib NE, Freegard TJ, Gock G, et al. Late surface opacification of Hydroview® intraocular lenses. Eye 2002;16:69-74. 22. Dagres E, Khan MA, MBBS, et. al. Perioperative complications of intraocular lens exchange in patients with opacified Aqua-Sense lenses. J Cataract Refract Surg 2004;30:2569-73. 23. Dahlmann AH, Dhingra N, Chawdhary S. Acrylic lens exchange for late opacification of the optic. J Cataract Refract Surg 2002;28:1713-4. 24. Preussner P-R, Wahl J, Weitzel D, et al. Predicting postoperative intraocular lens position and refraction. J Cataract Refract Surg 2004;30:2077-83. 25. Suto C, Hori S, Fukuyama E, Akura J. Adjusting intraocular lens power for sulcus fixation. J Cataract Refrac Surg 2003;29:1913-7. 26. Kora Y, Shimizu K, Yoshica M, et al. Intraocular lens power calculation for lens exchange. J Cataract Refract Surg 2001;27:543-8. 27. Holladay JT. Standardizing constants for ultrasonic biometry, keratometry, and intraocular lens power calculations. J Cataract Refract Surg 1997;23:1356-70. 28. Lowery MD, Makker H, Lang A. Effect of the speed of sound in Sensar acrylic lenses on pseudophakic axial length measurements. J Cataract Refract Surg 2002;28:1269-70. 29. Lee SB, Choi SH. Ultrasonic determination of axial length in pseudophakia. J Korean Ophthalmol Soc 2000;41:1164-9. 30. Hoffer KJ. Ultrasound velocities for axial eye length measurement. J Cataract Refract Surg 1994;20:554-62. 31. Holladay JT, Prager TC. Accurate ultrasonic biometry in pseudophakia. Am J Ophthalmol 1989;107:189-90. 32. Holladay JT, Prager TC. Accurate ultrasonic biometry in pseudophakia. Am J Ophthalmol 1993;115:536-7. 235