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Posterior capsule opacification (PCO) following cataract surgery is the manifestation of migration and proliferation of lens epithelial cells onto the central region of the posterior capsule. 1 The presence of a posterior chamber intraocular lens (IOL) in the capsular bag has been known to reduce the risk of PCO development, 2-5 probably by acting as a mechanical barrier against the migration of proliferating lens epithelial cells on the posterior capsule, 2-7 and/or minimising capsule wrinkling and limiting the space available for lentoid formation. 8 These effects are thought to be enhanced when an IOL has more contact with the posterior capsule, 1 and thus may be influenced by the degree of adhesion between the lens capsule and IOL optic. However, little is known about the mechanical and physical adhesion of the IOL to the crystalline lens capsule.
Several new materials are currently available for the fabrication of the IOL optic. 9 The interaction between the lens capsule and the IOL may vary among materials, depending on their adhesive properties, among other factors. We conducted this experimental study to assess the adhesive force between several IOL materials and the lens capsule, and to evaluate its possible role in preventing the migration of lens epithelial cells.
Materials and methods
IN VITRO STUDY
Adhesion between a collagen sheet and IOL optic was measured. The sheet consisted of purified type I collagen which was pepsinated and extracted from insoluble collagen of bovine derma (Kokencellgen Men-01, Funakoshi Inc, Tokyo, Japan). The IOLs tested were single piece polymethylmethacrylate (PMMA) (MZ60BD, Alcon Laboratories, Fort Worth, TX, USA), three piece silicone (SI-30NB, Allergan Medical Optics, Irvine, CA, USA), and three piece acrylic foldable (MA60BM, Alcon Laboratories) IOLs. All IOLs had a biconvex optic of 6.0 mm in diameter. Measurements were carried out in water using a tension meter (Autograph AGS-D, Shimazu Seisakusho, Tokyo).
The collagen sheet was sandwiched between two plastic rings and horizontally suspended in a balanced salt solution (BSS Plus, Alcon Laboratories) maintained at 22°C. The haptics of the IOL were removed by snipping in order to prevent their contact to the sheet. Before the measurement, the IOL optic attached to the plunger of the tension meter was gently placed onto the collagen sheet with a positive power of 1000...