November 2007

 

CATARACT/ IOL

 

Effect of UV absorber in IOLs deviates from existing literature


 
 

 

A study, published in the October issue of Optometry & Vision Science suggests that the presence of the UV absorber in IOLs significantly affects its dispersive properties.

Researchers Damian Siedlecki, Ph.D., Wroclaw University of Technology, Poland, and Harilaos S. Ginis, Ph.D., University of Crete, Greece, wrote in their study that biocompatibility and stability over time after implantation are the primary properties of the optical materials used for IOLs. They noted that modern IOLs also need to be flexible so that they can be implanted through a small incision. Several compounds are therefore usually added to existing materials (such as acrylic) to enhance these properties, they wrote. In addition, UV-absorbing substances are added in the IOL materials to mimic the spectral transmittance of the natural lens. Although manufacturers usually provide information for the geometry of IOLs, chromatic dispersion data are usually not available, the researchers wrote. The study therefore set out to estimate the dispersion properties of a few materials used for IOLs. According to the study, the researchers measured the chromatic focal shift of two common types of IOLs using a simple, optical method. They calculated the dispersion properties of the materials (polymethylmethacrylate and acrylic) used for the IOLs under investigation from the chromatic focal shift.

The study yielded results that deviate from the existing data in the literature for the corresponding pure materials, the researchers wrote. Data pointed to the presence of the UV absorber in the optic material as having a significant effect on its dispersive properties. Longitudinal chromatic aberration (LCA) of the IOLs is about three times higher than LCA of the natural crystalline lens, the researchers wrote. The researchers noted that eyes implanted with IOLs are expected to suffer from increased LCA in comparison with intact eyes.

Reported by: EyeWorld News Service

Effect of UV absorber in IOLs deviates from existing literature Effect of UV absorber in IOLs deviates from existing literature
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