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 200F 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

Posterior edge appears always on the left Some IOLs required cutting of the haptic and/or optic to view edge

Measurement of Radius of Curvature of Posterior Optic Edge

R P L r Customised computer program measures the local radius of curvature R P r L Sharper optic edge = Smaller r See details in J Cataract Refract Surg, April 2008.

8.5µ

Hydrophobic Acrylic IOLs

9.3µ 9.9µ Alcon AcrySof IQ Alcon AcrySof Natural Alcon AcrySof MA60AC

8.3µ

Hydrophobic Acrylic IOLs

19.9µ AMO Sensar AR40e Hoya AF-1(UY)

15.9µ

Hydrophilic Acrylic IOLs

14.3µ 23.1µ B & L Akreos 15.5µ B & L MI60 Lenstec Tetraflex Rayner Superflex

8.6µ

Hydrophilic Acrylic IOLs

9.1µ Human Optics 1CU Human Optics MC611 MI-B

8.3µ Silicone IOLs 7.6µ Bausch & Lomb Soflex SE Bausch & Lomb SofPort AO

8.3µ Silicone IOLs 9.2µ 9.0µ AMO Clariflex AMO Tecnis Z9000 AMO Tecnis ZM9000

Hydrophobic Acrylic IOLs Hydrophilic Acrylic IOLs Silicone IOLs

Summary

Alcon AcrySof ® SN60WF Alcon AcrySof ® SN60AT Alcon AcrySof ® MA60AC AMO Sensar ® AR40e Hoya ® AF-1(UY) Rayner ® C-flex (thinnest ridge) Rayner ® C-flex (thickest ridge) Rayner ® Superflex (thinnest ridge) Rayner ® Superflex (thickest ridge) Bausch & Lomb Akreos ® Bausch & Lomb MI60 HumanOptics ® 1CU HumanOptics ® MC 611 MI-B Tetraflex ® Bausch & Lomb Soflex ® Bausch & Lomb SofPort ® AO AMO Clariflex ® AMO Tecnis ® Z9000 AMO Tecnis ® ZM9000

Radii of curvature (µ)

8.5

9.3

9.9

8.3

19.9

18.2

19.6

15.6

10.6

15.9

14.3

8.6

9.1

23.1

8.3

7.6

8.3

9.2

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 manufacturing techniques.

reflects difference in • 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.