Contact Lens Wettability Research Articles

Comparison of two contact lens storage solution preservatives with respect to in-eye wetting of rigid oxygen-permeable lens surfaces and related factors

Wettability of contact lenses made of four rigid oxygen-permeable materials was assessed over a 4-month period when the lenses were worn in a daily-wear manner by 16 previously successful rigid contact lens wearers. The lenses were maintained with care regimens using two storage solution preservatives, 0.004% benzalkonium chloride (BAK) and 0.006% chlorhexidine digluconate (CHX), in isotonic-buffered saline. Wettability was evaluated by use of the in vivo contact angle, lens-surface break-up time, graded levels of surface deposition and discomfort, and by frequency of occurrence for verified presence and absence of functional wettability. Statistically significant effects of patient, lens material, care regimen (preservative), and their interactions were found, which led to a complicated statistical analysis of the results. Overall, low oxygen-permeability lens materials fared better with respect to wettability, as did the BAK-containing care regimen, but the results were patient-specific with regards to favor of any single lens material/care regimen combination. Results also varied according to the wettability assessment method used, although the methods have been previously shown to be loosely correlated. The contact lens practitioner is at a disadvantage for selecting the optimum lens material/care regimen combination for the individual patient, because the wettability assessment techniques at his/her disposal give conflicting results, because those results are highly specific with respect to the combination of patient, lens material, and care regimen and because he/she has a practical lack of information and limited diagnostic repertoire from which to make clinical predictions.