Edge profile of commercially available squareedge intraocular lenses
Edge profile of commercially available square-edge intraocular lenses Mayank A. Nanavaty 1 David J. Spalton 1 James Boyce 2 Anthony Brain 2 John Marshall 2 1. St. Thomas’ Hospital, London 2. King’s College, London Financial interests: None
Aim To analyze the sharpness of the posterior optic edge of intraocular lenses (IOLs) marketed with a ‘square-edge’ profile. Methods • Seventeen IOLs of different designs and material all marketed as ‘square-edge’ IOLs • 20 Diopter IOL of each selected • IOLs examined with environmental scanning electron microscopy
FEI Quanta 200 F field emission gun environmental scanning electron microscope was used to examine IOLs Parameters standardized for all IOLs • 93. 3 Pascal (0. 7 torr), • Specimen temperature of 20 o. C, • Voltage of 15 KV • Magnification x 500 • Average processing time 25 minutes IOLs mounted using a simple microscope Haptic excised Some IOLs required cutting of the Posterior edge appears always on the left haptic and/or optic to view edge
Measurement of Radius of Curvature of Posterior Optic Edge Customised computer program measures the local radius of curvature L P R r r Sharper optic edge = Smaller r See details in J Cataract Refract Surg, April 2008.
Hydrophobic Acrylic IOLs 9. 9µ 9. 3µ 8. 5µ Alcon Acry. Sof IQ Acry. Sof Natural Acry. Sof MA 60 AC
Hydrophobic Acrylic IOLs 8. 3µ AMO Sensar AR 40 e 19. 9µ Hoya AF-1(UY)
Hydrophilic Acrylic IOLs 15. 9µ 14. 3µ B & L Akreos 23. 1µ Lenstec Tetraflex B & L MI 60 15. 5µ Rayner Superflex
Hydrophilic Acrylic IOLs 8. 6µ Human Optics 1 CU 9. 1µ Human Optics MC 611 MI-B
Silicone IOLs 8. 3µ Bausch & Lomb Soflex SE 7. 6µ Bausch & Lomb Sof. Port AO
Silicone IOLs 9. 2µ 8. 3µ 9. 0µ AMO AMO Clariflex Tecnis Z 9000 Tecnis ZM 9000
Summary Hydrophobic Acrylic IOLs Hydrophilic Acrylic IOLs Alcon Acry. Sof® SN 60 WF 8. 5 Alcon Acry. Sof® SN 60 AT 9. 3 Alcon Acry. Sof® MA 60 AC 9. 9 AMO Sensar® AR 40 e 8. 3 Hoya® AF-1(UY) 19. 9 Rayner® C-flex (thinnest ridge) 18. 2 Rayner® C-flex (thickest ridge) 19. 6 Rayner® Superflex (thinnest ridge) 15. 6 Rayner® Superflex (thickest ridge) 10. 6 Bausch & Lomb Akreos® 15. 9 Bausch & Lomb MI 60 14. 3 Human. Optics® 1 CU Human. Optics® MC 611 MI-B Tetraflex® Silicone IOLs Radii of curvature (µ) 8. 6 9. 1 23. 1 Bausch & Lomb Soflex® 8. 3 Bausch & Lomb Sof. Port® AO 7. 6 AMO Clariflex® 8. 3 AMO Tecnis® Z 9000 9. 2 AMO Tecnis® ZM 9000 9. 0
Conclusion • Commercially marketed ‘square edge’ IOLs differ in posterior edge sharpness. • Most hydrophobic acrylic and silicone IOLs have sharper posterior optic square edges compared to most hydrophilic acrylic IOLs. This probably reflects difference in manufacturing techniques. • The difference in the posterior optic edge profile may explain why some IOLs have relatively poor PCO performance and may explain why some IOL materials appear to have better PCO performance than others.
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