Purpose:
To determine if the interactions of lens care preservatives with contact lenses is an important factor in clinical signs and symptoms.
Methods:
This study evaluated uptake and release profiles of two preservatives used in MPS products, alexidine contained in ReNu* with MoistureLoc* and POLYQUAD® (polyquaternium-1) contained in OPTI-FREE® EXPRESS® MPDS. Three lens materials were used in a cross over study design: SofLens* 66 (alphafilcon A), Acuvue* Advance* (galyfilcon A, with HYDRACLEAR*). Asymptomatic, adapted daily wear soft lens users wore groups I and IV soft hydrophilic or silicone hydrogel lenses for a maximum of 2, 4 and 6 hours each day. New lenses were dispensed for each wear period. The worn lenses were analyzed for preservative content using HPLC and release profiles calculated. Short-term changes in corneal staining and ocular symptoms were assessed at defined time intervals following lens insertion in order to compare these ocular findings with laboratory uptake and release properties.
Results:
All three lens types uptake alexidine during an overnight soaking period. The rate of preservative release during wear depended on the lens type. After 2 hours, Acuvue* 2 and SofLens* 66 released 46% and 77% of alexidine, respectively. Acuvue* Advance* released 27% of the preservative in two hours. Clinically significant corneal staining was observed at 2 and 4 hours when subjects wore Acuvue* 2 and Acuvue* Advance* lenses soaked in the alexidine-based
system. At the 2 hour interval, extent of corneal staining increased in all subjects with Acuvue* 2 lenses, and 50% of the subjects with Acuvue* Advance* lenses. Only minimal staining was observed for SofLens* 66 at 2, 4 and 6 hours. Symptoms were not correlated with the extent of staining. Lenses cycled in the POLYQUAD® – based product showed minimal uptake into lenses and corneal staining was low with all lens materials tested.
Conclusion:
The study demonstrated the difference in uptake/release profiles for MPS products preserved with alexidine or POLYQUAD® using three soft lens materials. For some lens materials these differences in biocide uptake/release appear to be correlated with corneal staining patterns but not symptoms.
Citation:
