Purpose:
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.
Methods:
Fifty adapted soft-lens wearers were fitted with a siliconehydrogel
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 (polyquaternium-1) – based
system or a polyaminopropyl biguanide (PHMB) – based system, using a
double-masked, randomized crossover experimental design.
Results:
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
solutioin-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).
Conclusion:
Practitioners who fit silicone-hydrogel contact lenses on
a daily wear basis should be wary of the potential for certain PHMB-containing
multi-purpose care systems to invoke corneal staining.
Switching to non-PHMB based regimens will eliminate this complication
in most instances.
Citation:
