Contact lenses and mechanical trauma to the eye. An experimental study

Eyes of anaesthetized rabbits, fitted with contact lenses, were exposed to showers of burning grit particles. Hard contact lenses provided efficient protection for the covered part of the cornea. Soft lenses also had a certain protective effect since the majority of the particles rebounded and the others caused only superficial epithelial damage to the cornea. The soft lenses were themselves heavily damaged. Exposure to attack by large particles of metal was also tested. The hard lenses, which splintered at a lower energy than that required for penetration of the cornea, could increase the risk of injury by penetration of splinters of plastic. Soft lenses with high liquid content constituted neither a protection nor a risk. Soft lenses with low water content were, however, significantly different from the other types since a considerably higher momentum of the particles was required for penetration of the cornea when covered by such lenses.