Rotational Stability of Single-Piece Hydrophobic Acrylic Intraocular Lens During Removal of OVD

1. Rotational Stability of Single-Piece Hydrophobic Acrylic Intraocular Lens During Removal of OVD Hwan Eok Yeo, MD1,4 Won Ryang Wee, MD2,3 Jin Hak Lee, MD1,3 Joon Young Hyon, MD1,3 1. Department of Ophthalmology, Seoul National University Bundang Hospital, Seongnam, Korea 2. Department of Ophthalmology, Seoul National University Hospital, Seoul, Korea 3. Seoul National University College of Medicine, Seoul, Korea 4. Kim’s Eye Hospital, Seoul, Korea The authors have no financial interest

2. Purpose • The toric IOL with a single-piece hydrophobic acrylic platform showed satisfactory postoperative torsional stability. However, unintended intraoperative rotation of the IOL may occur during removal of the OVD • To evaluate the rotational stability of a foldable hydrophobic single-piece acrylic IOL during removal of OVD and assess the suitability of IOL platform as a toric lOL

3. Patients and Methods • 20 eyes of 20 patients • Prospective study • The position of the IOL was determined from digital photograph during surgery • Before and After removal of OVD • Unintended over-rotation of the IOL was measured with image analysis

4. Patients and Methods • Surgical Technique • 2.75 mm temporal clear corneal incision • Phacoemulsification • OVD • Cohesive : Healon GV® • Dispersive : Viscoat®

5. Comparison axis: using 2 critical details on the IOL α reference axis: using 2 critical details on conjunctiva or cornea Image analysis

6. Results • The mean IOL rotation • 17.1 ± 11.1 degree • Range from 0.9 up to 42.7 • Rotation within 5 degree: 15 % • Rotation of 5 degree to 15 degree: 25% • Rotation over 15 degree: 60 % • The mean IOL rotation of two OVDs • Cohesive OVD: 22.5±9.3 degree • Dispersive OVD: 11.6±10.28 degree

7. IOL Rotation During Removal of OVD Clockwise rotation Counter-clockwise rotation

8. Discussion • Toric IOL implantation is a predictable and precise method to control the preexisting corneal astigmatism during cataract surgery • In the present study, 85 % of IOLs were out of 5 degree of intended axis • The numbers of clockwise rotation were more than those of counterclockwise rotation • Better torsional stability with dispersive OVD

9. Discussion • The differences in the rotational angle during removal of OVD may be explained by several factors • IOL design • Capsular bag size • Character of OVD • Surgical techniques • starting of removal before fully unfolding of IOL, aggressive irrigation and aspiration, anterior chamber collapse after drawing of the I&A device

10. Conclusion • IOL rotation could occur during removal of OVD, amount of which may be visually significant • Verification of the IOL axis after removal of OVD should be warranted to achieve the intended amount of astigmatic correction with the toric IOL of a single-piece hydrophobic acrylic platform

11. References Hoffer KJ. Biometry of 7500 cataractous eyes. Am J Ophthalmol 1980;90:360-368; correction, 890. Horn JD. Status of toric intraocular lenses. Curr Opin Ophthalmol 2008;18:58-61. Viestez A, SeitzB, Langenbucher A. Evaluating the eye’s rotational stability during standard photography. Effect on determining the axial orientation of toric intraocular lenses. J Cataract Refract Surg 2005; 31: 557-561. Weinand F, Jung A, Stein A, Pfutzner A, Becker R, Pavlovic S. Rotational stability of a single-piece hydrophobic acrylic intraocular lens: New method for high-precision rotation control. J Cataract Refract Surg 2007;33:800-803. Chang DF. Early rotational stability of the longer Staar toric intraocular lens. J Cataract Refract Surg 2003; 29:935-940. Patel CK, Ormmonde S, Rosen P, Bron AJ. Postoperative intraocular lens rotation; a randomized comparison of plate and loop haptic implants. Ophthalmology 1999;106:2190-2196; discussion 2196. Vass C, Menapace , Schmetterer K, et al. Prediction of pseudophakic capsular bag diameter based on biometric variables. J Cataract Refract Surg 1999; 25:1376-1381.