[Barrier function of the corneal epithelium of contact lens patients]

The corneal epithelium of contact lens wearers is permanently under stress. The aim of the present study was to examine the following questions prospectively and quantitatively: (1) whether or not wearing contact lens leads to a disturbance of corneal epithelial barrier function and (2) if there is a difference between CAB and HEMA contact lenses in this respect. For this reason, the corneal epithelial permeability to sodium fluorescein in 50 individuals was measured before and 8 weeks after fitting contact lens using an automated computerized fluorophotometer (Coherent Radiation Fluorotron Master). Twenty five of the 50 individuals were provided with CAB or HEMA (38%) contact lenses, respectively. Eight weeks after fitting the contact lens corneal epithelial permeability was found to be increased about 1.5 times (p less than 0.001). There was no significant difference between the HEMA and CAB group before and 8 weeks after wearing contact lens (p = 0.5 and p = 0.7, respectively). In conclusion, the corneal epithelium of contact lens wearers is obviously significantly more permeable to watery ionic substances, e.g., water-soluble drugs and toxic products.