[Damage caused by wearing contact lenses throughout the day].

Seventy-eight contact lens patients issued with soft HEMA lenses were examined in order to establish reasons for intolerance. The examination was carried out in conjunction with a questionnaire designed to furnish information about the habits of the contact lens patients. Less than 50% of the patients had been advised to have their lenses checked. Almost all the patients wore their contact lenses all day without interruption. On average they had been wearing the lenses for up to 17 hours per day over a 3.3 year period. In approximately 2/3 of the cases the eye had suffered some damage and in approximately 1/3 of the cases the effects were more serious. Patients who had worn their lenses for even longer periods of time had suffered still more severe eye damage. However, microbiological findings, allergies to the cleaning fluids, reduced tear production, incorrect lens fit and severe deterioration of the lens material were not found to be the prime causes of intolerance. Photographs shot by SEM showed evidence of defects of the corneal surface after the HEMA lens had been worn 18 hours.