Abstract
Purpose: :
The poly(vinylpyrrolidone) (PVP) hydrogel is a hydrophilic material that has a water content of 90% and a swelling rate of 230%. The clarity and elasticity of this material are equal to those of the crystalline lens in the aqueous humor. To determine the safety and potential of this polymer as a material for accommodative IOLs, we performed a short–term implant test in rabbits.
Methods: :
Female Japanese White rabbits weighting 2.0 to 2.5 kg were used. In 4 eyes, endocapsular phacoemulsification was performed and the PVP hydrogel was implanted into the capsular bag through a 5.0–mm sclerocorneal incision. Slitlamp examination was performed at 2, 7, 14, 21 and 28 days postoperatively, and fundus examination at 28 days postoperatively. Three eyes were enucleated at 28 days postoperatively and examined by Miyake–Apple view observation. The material structure was examined by scanning electron microscopy. The clarity was evaluated by transmittance of visible light, and the elasticity by compression force with which the material was compressed by 1.0–mm thickness. The results were a comparison of before and after implantation.
Results: :
The PVP hydrogel began to swell immediately, and the lens capsule was successfully refilled within 10 minutes. Two eyes developed hypopyon due to capsule rupture, which was caused by the PVP hydrogel swelling larger than expected by 14 days postoperatively. In the other 2 eyes, the slitlamp examination revealed no inflammatory reaction or corneal opacification for 28 days. In addition, the retina and optic nerves were clinically observable through the PVP hydrogel. The Miyake–Apple view observation showed the material filling the capsular bag and cortical remnants existing in the capsular bag. The PVP hydrogel formed three–dimensional networks of 1– to 10–µm mesh, and cells adhered onto the material surface. The material showed over 80% transmittance at wavelengths 400 to 800 nm, and the compression force was below 5.0 g/cm2. These results remained unaltered after implantation.
Conclusions: :
The PVP hydrogel successfully filled the capsular bag and maintained their clarity and elasticity. These results suggest that PVP hydrogel could serve as a biocompatible material for accommodative IOLs. Further study is necessary to improve the shape of the PVP hydrogel and to conduct long–term observation.
Keywords: crystalline lens • intraocular lens • refraction