To compare subjective symptoms and signs in a group of individuals who wear silicone-hydrogel lenses on a daily wear basis while they sequentially used two differing care regimens.
Fifty adapted soft-lens wearers were fitted with a silicone-hydrogel lens material (PureVision, Bausch & Lomb). The lenses were worn on a daily wear basis for two consecutive 1-month periods, during which the subjects used either a Polyquad
) -based system or a polyaminopropyl biguanide
(PHMB) -based system, using a double-masked, randomized, crossover experimental design.
Significant levels of relatively asymptomatic corneal staining
were observed when subjects used the PHMB-based system, with 37% of subjects demonstrating a level of staining consistent with a classical solution-based toxicity reaction. Only 2% of the subjects exhibited such staining when using the Polyquad
-based system. These results were significantly different (p < 0.001). Significant symptoms were not correlated with the degree of staining, with no differences in lens comfort or overall preference being reported between the regimens (p = NS). The only statistically significant difference in symptoms related to minor differences in stinging after lens insertion being reported, with the Polyquad
-based system demonstrating less stinging (p < 0.008).
Practitioners who fit silicone-hydrogel contact lenses
on a daily wear basis should be wary of the potential for certain PHMB-containing multipurpose care systems to invoke corneal staining
. Switching to non-PHMB based regimens will eliminate this complication in most instances.