Edge profile of commercially available square-edged intraocular lenses.
OBJECTIVE
To analyze the sharpness of the posterior optic edge profile and edge thickness of intraocular lenses (IOLs) marketed with a square-edged profile.


METHODS
Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.


METHODS
Seventeen square-edged 20.0 diopter IOLs of different manufacture, design, and material were selected. After the environmental scanning electron microscopy technique was standardized, repeatability of the technique was tested. Posterior optic edges of all IOLs were scanned at a magnification of x 500. Local radii of curvature of the posterior optic edges were measured by purpose-designed software. Optic edge thickness was also measured from the electron micrographs.


RESULTS
The repeatability of the scanning technique was excellent (+/-0.10 microm). The radius of curvature of posterior optic edges ranged from 7.6 to 23.1 microm. Hydrophilic acrylic IOLs (except the HumanOptics MC Microlens 611 MI-B and 1CU) had radii of curvatures more than 10.0 microm of the posterior optic edge compared with hydrophobic acrylic and silicone IOLs (<10.0 microm) except the Hoya AF-1 (19.9 microm). Alcon AcrySof single-piece (SN60WF), HumanOptics 1CU, and AMO Clariflex CLRFLXC IOLs had the thinnest optic edges in the hydrophobic, hydrophilic, and silicone groups, respectively.


CONCLUSIONS
Commercially marketed square-edged IOLs differed in the sharpness of the posterior optic edge. Hydrophobic acrylic and silicone IOLs have sharper posterior optic square edge than most hydrophilic acrylic IOLs. This probably reflects difference in manufacturing techniques. Differences in posterior optic edge profile may explain variation in posterior capsule opacification performance with different IOLs and materials.
Nanavaty
Mayank A
MA
Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.
Spalton
David J
DJ
Boyce
James
J
Brain
Anthony
A
Marshall
John
J
D007910:Lenses, Intraocular; D008855:Microscopy, Electron, Scanning; D011474:Prosthesis Design