An investigation of intraocular lens damage and foreign bodies using an injectable hydrophilic acrylic lens implant.

AIMS: To determine the nature of intraocular lens (IOL) surface abnormalities seen after the injection of hydrophilic acrylic lenses (Rayner C-flex 570C), through their accompanying pre-packaged disposable injectors. Hexagonal and round nozzle injectors from the same lens manufacturer were compared. METHODS: A series of lenses were injected into a petri dish, using two different manufacturer-supplied disposable injectors. The injector nozzle, plunger, and IOL were subsequently examined by light and scanning electron microscopy (SEM) for defects. RESULTS: When using the hexagonal nozzle, eight out of nine lenses had linear surface abnormalities along the posterior surface of the IOL in the direction of injection. These abnormalities appeared to be scratches on the surface of the IOL and there were no corresponding defects on the nozzle. A newly introduced injector, with an oval nozzle and a larger compressible plunger, eliminated the vast majority of these surface abnormalities. CONCLUSIONS: Manufacturer-supplied hexagonal nozzle injectors, but not oval nozzle injectors, produce linear scratches on the posterior surface of the IOL. These scratches did not disappear with time in vivo.

A reciprocal relationship between cutaneous nerves and repairing skin wounds in the developing chick embryo.

Various studies have suggested that the rate of adult skin healing may be in some way dependent on signals emanating from cutaneous nerves. Further, it appears that adult wounds become hyperinnervated by sensory nerves during the process of healing. In order to investigate this reciprocal relationship further, we have used a simple embryonic model to look at the effect of wounds on nerves, and conversely, the effect of nerves on wounds. We find that wounds made to the dorsum of the chick wing bud, at a stage prior to normal innervation (at E4), or soon after the normal establishment of cutaneous innervation (at E7), subtly alter the pattern of branching by perturbing developmental guidance cues, but do not cause hyperinnervation, whereas wounding at E14 does cause hyperinnervation. By creating chicks with nerveless wings, we show that from E7, wound healing in the absence of nerves is significantly impaired. These observations suggest that, from the earliest stages of skin innervation, the presence of nerves is beneficial to the healing process, but that, in contrast to neonatal and adult tissues, wound healing in the embryo and early foetus does not trigger hyperinnervation.