SANDWICH-LENS INTRAOCULAR IMPLANT - A CON CEPT FOR CORRECTION OF APHAKIA IN INFANTS

Background In the management of congenital cataracts the correction of aphakia is still an unsatisfactorily solved problem. As far as surgic al techniques and materials are concerned, the implantation of an IOL seems to be justified even in younger children; but choosing the refra ctive power of the lens is somewhat difficult regarding the expected g rowth of the eye. Materials and methods A new type of IOL is presented as a solution for this problem. Being composed of a PMMA-fashioned op tic and haptic it bears a silicone lens which is fastened on top of it . The supporting lens is made of PMMA (polymethylmethacrylate) with a biconvex surface with modified J-loops. The diameter of the optic is 6 mm, the overall diameter is 11 mm. The supplementary lens is made of the same silicone material as used for foldable intraocular lenses. It s diameter is 4.5 mm. This additional component can be removed from th e implanted lens so that the needed reduction of refractive power afte r completed growth of the eye can be performed. The PMMA-fashioned bas ic component remains in situ just like a conventional posterior chambe r lens. The lens was examined using scanning-electron microscopy. Im- and explantation was performed in isolated porcine eyes. Results The h igh quality of the lens could be demonstrated using scanning-electron microscopy. The technical feasibility of this concept could be demonst rated on isolated porcine eyes. Discussion Currently the sandwich lens is being tested in animal experiments. Our special interest is focuss ed on biocompatibility, formation of secondary cataract, biological re actions in the interface and the possibility of atraumatic explantatio n of the silicone lens.