The circular haptic of the IOL is the best geometry for a strong adhesion between IOL and inner surface of the capsular bag. The treatment time of 120 s has only little influence on the surface topography of the haptic, the best results for protein adsorption and comparably low cell adhesion.
The biocompatibility of the siloxane film is excellent and furthermore it is not affected by plasma etching. Cell spreading increases clearly when the hydrophilic surface has been coated with collagen IV and laminin. Protein adsorption increases under the following conditions:
etching time ò 120 s
a for storage times up to 24 hours after plasma treatment
storage in a physiological NaC1 solution.
The in vitro-migration assay shows that the cell migration decreased by approx. 10% on plasma etched and protein coated (sandwich coating of collagen and laminin) silicone films. For treatment times exceeding 120 s, however, a decrease by 30% can be observed compared to the cell migration on untreated films. On surfaces coated with either laminin or collagen IV cell migration is not inhibited between the silicone film and the capsular bag.
In the animal experiments (dwarf rabbits) the SO2 plasma etched IOLs show minor histological signs of posterior capsule opacification (PCO) in comparison to the unmodified and protein coated IOLs. A thin layer (probably a fibrin layer) between the IOL and the capsule prevents the direct contact and allows to establish a bonding between the IOL surface and inner layer of the capsular bag.
From an eye-surgeons point of view the modification of the lens surface is a very interesting innovative new approach to cataract surgery.
Summing up one finds that the appropriate surface modification of the IOLs' haptic reduces cell migration on the optical part of the IOL, Thus the project succeeded in developing an IOL avoiding secondary opacification.
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