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G. A. Zikos, S. S. Kang, R. J. Nason, A. Selenow, S. R. Ali; Objective in vivo Contact Lens Wettability Testing With Different MPS Using the Shack-Hartmann Sensor. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4855. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the feasibility of using a Shack-Hartmann Sensor image in identifying differences in pre-lens tear film stability (and therefore wettability) of two contact lens materials soaked in different multi-purpose solutions (MPS).
A COAS Shack-Hartman wavefront sensor was used to collect continuous measurements for 10 seconds after blink. The wettability index metric (WI) used was based on the slope of the linear regression of the processed Shack-Hartman image. Four sets of measurements were taken at 10 min and 30 min after insertion and at the end of day (EoD) (mean 8.5 hrs). Blinking was controlled at 30 blinks/min for 3 minutes before each measurement. Two groups of 9 habitual contact lens wearers using either a Group 4 hydrogel contact lens (H) or a silicone hydrogel contact lens (SiH) participated. New lenses were soaked in either ReNu MultiPlus® MPS or Opti-Free® RepleniSH® MPS for a minimum of 12 hrs before dispensing. The solution presentation order was counterbalanced across all participants. During testing, room temperature and humidity were recorded.
A significant improvement (p<0.05, T-Test) of the lens wettability was observed for the SiH group with use of OF (WI=-762) vs. RN (WI=-1131) MPS, but not for the H group (OF WI=-674 vs. RN WI=-635). The differences were noted mostly at the 10 minute and EoD measures. Room temperature and humidity variability did not correlate with the measured WI (r^2=0.008 and 0.002, respectively).
The use of this novel wettability index metric (WI) is promising in objectively characterizing differences in in-vivo surface wettability. Differences in soft contact lenses treated with different care solutions have been detected. Future applications in dry eye treatments, contact lens materials and their interactions with solutions may be possible.
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