Abstract
Purpose: :
To determine the ocular and subjective responses to two multipurpose disinfecting solutions (MPDS) used in combination with two silicone hydrogel lenses.
Methods: :
10 subjects per lens type (required to determine a difference of 1 ± 1 in subjective ratings and 0.5 ± 0.5 in clinical grades with 80% power and 5% level of significance) were asked to wear lenses (either Lotrafilcon B or Galyfilcon A) bilaterally for 6 hours. Lenses had been soaked in a lens solution containing either PHMB or Polyquat as the dominant antibacterial agent, or were worn straight from the packet. After soaking, lens parameter measurements were conducted using standard techniques. Subjects were asked to rate the comfort of the lenses. Cornea and conjunctival staining and conjunctival and limbal redness was assessed using slit lamp biomicroscopy. The amount of MPDS released from lenses over a 6h period was assessed by measuring release of material from lenses by spectroscopy. X-ray photoelectron spectroscopy (XPS) was used to determine elemental (C, O, N, Si, F) changes to the lens surface during soaking.
Results: :
None of the lens parameters altered significantly during soaking in either MPDS. Redness was not affected by soaking in MPDS, but there was an increase in corneal staining only when either lens was soaked in PHMB. For lotrafilcon B lenses compared to control, there was a significant decrease in comfort and increase in burning/stinging sensation after soaking in PHMB, whereas there was an increase in lens awareness and eye itchiness when soaked in Polyquat. For Galyfilcon A lenses compared to control, there was an decrease in comfort and increase in burning/stinging, eye redness, pain upon insertion, tearing upon insertion and lens awareness when soaked in Polyquat. There was only a slight but significant increase in burning/stinging when lenses were soaked in PHMB but no other significant differences when compared to control lenses. There were significant changes to the elemental composition of the lens surface when soaked in MPDS. For example, for lotrafilcon B lenses soaked in PHMB when compared to control, there were significant increases in N/C, C1+C2/C, C4/C, C5/C, N1/C and N2/C but a decrease in C3/C. For Galyfilcon A lenses soaked in PHMB when compared to control, there were significant increases in O/C, Si/C, C1+C2/C, C4/C and C5/C but decreases in N/C and C3/C.
Conclusions: :
These data demonstrate that MPDS can affect ocular comfort during wear. These affects may be due to changes in the elemental composition of the surface of lenses after their soaking in different MPDS solutions.