Ocular growth and lens size

Sammanfattning: Ocular axial length growth was investigated with special reference to the influence of crystalline lens and different intraocular lens implants, in human infants and three week-old rabbits. First it was concluded, in a retrospective study of children with bilateral congenital cataract, that lensectomy during the first months of life resulted in almost normal visual development. Second, in a prospective study of children with unilateral congenital cataract, it was found that the visual outcome was poor. This lead to a study in which the cataractous eye and the fellow eye were compared side by side. It was found that ocular axial length was retarded in the cataractous eye and that the cataractous lens was thinner. This was investigated further in an experimental rabbit model. Lensectomy in the three week-old rabbit resulted in retarded axial length growth and growth of corneal diameter compared to the unmanipulated eye. Implantation of a polymethyl methacrylate intraocular lens retarded axial length growth even more compared to the aphakic eye. A softer silicone intraocular lens improved growth slightly, and a thicker implant seemed to be more favourable than a thinner implant. The effect of the aphakic correction of an intraocular lens towards the uncorrected aphakic eye was eliminated by replacing the lens with capsule-tension-rings of different sizes. This findings suggests that the tension of the implant on the ciliary body and peripheral retina was important for the degree of growth retardation. Furthermore, it was found that implantation of an intraocular lens and a large capsule-tension ring inhibited the formation of after-cataract. In conclusion, it was found that both crystalline lens and implantation of different intraocular lenses into the eyes of human infants or young rabbits, interfere with ocular growth and after cataract formation. Accordingly this has to be considered when designing intraocular lenses for implantation in young infants. Key words: congenital cataract, lens thickness, intraocular implants, ocular axial length, corneal diameter, infant eye, rabbit eye ISBN 91-628-2235-7