Variations in manufacturing quality of diffractive multifocal lenses.
The new generation of multifocal intraocular lenses (IOLs) based on diffraction optics is characterized by a stepped discontinuity at zone boundaries on the posterior surface of the IOL optic. The step height at the zone boundaries is less than 2 microns. There are approximately 30 zones on a 6 mm diameter lens, requiring manufacturing precision of about 0.02 mm. Various companies produce this type of lens. On two implanted lenses we found, in addition to the 2 microns boundaries, many small circular rims that appeared to be manufacturing artifacts. The presence of these artifacts may explain the variable clinical acceptance of these IOLs.
Wenzel
M R
MR
Department of Ophthalmology, Rheinisch-Westfalische Technische Hochschule, Aachen, Germany.
Imkamp
E M
EM
Apple
D J
DJ
D000368:Aged; D015350:Contrast Sensitivity; D005260:Female; D006801:Humans; D007910:Lenses, Intraocular / Q000009:adverse effects / Q000592:standards*; D008297:Male; D008855:Microscopy, Electron, Scanning; D055095:Optics and Photonics; D011474:Prosthesis Design / Q000592:standards; D011786:Quality Control; D014786:Vision Disorders / Q000503:physiopathology; D014792:Visual Acuity