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M. H. Wong; Daily-Disposable Soft Contact Lenses Wettability in vitro. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3423.
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To investigate the effect of blister-pack solution ingredients on in vitro surface wettability of daily-disposable soft contact lenses (SCLs).
Wettability of the contact lenses immersed in surfactant-free lens-care solution (LCS) was evaluated in a dynamic-cycling regime using a modified captive-bubble apparatus. The advancing and receding angles (CA) were measured concurrently with surface tension (ST). Conventional pHEMA-based lenses (e.g., Acuvue Moist, Dailies Aqua Comfort Plus, Proclear 1-Day, Clearsight 1-Day, Softlens), and a silicone hydrogel (SiH) lens (AcuvueTrueye) were studied. After measurements were performed on fresh lenses immediately removed from blister packs, lenses were soaked in 20 ml of LCS each and agitated overnight. CA and ST were measured on Day 1 and Day 7. ST of blister-pack solutions was measured by pendant drop method.
CA values of pHEMA-based lenses, after 7 days of soaking, increased by 17.0±11.4° (Softlens) to 46.5±9.8° (Acuvue Moist) (p<0.05). CA for AcuvueTrueye (SiH) increased by 9.5±11.8° after 7 days of soaking. ST of blister-pack solutions ranged from 31.0±3.6 (Softlens) to 56.8±1.6 mN/m (Clearsight 1-Day), compared to that of surfactant-free LCS (71.4 mN/m). After 7 days of soaking, the ST after lens-bubble equilibration increased to 55.5±5.9 and up to 61.6±6.9 mN/m. Lens-surface wettability of pHEMA-based lenses, gauged by aqueous adhesion energy (Eadh), was reduced by 9±10.7 (Softlens) to 20±6.3 mN/m (Acuvue Moist) after 7 days of soaking. For SiH-lenses (AcuvueTrueye), Eadh increased by 5.5±9.8 mN/m after prolonged soaking. For all the lenses, the receding angles were below 15°.
The surface-active ingredients of blister solutions or of lens matrixes contribute to wetting properties of all studied SCLs, although to different extents. Lower CAs were consistent with reduced ST by the surface-acting agents in unworn daily-disposable SCLs. SiH lenses exhibited stable and self-sustained in vitro surface wettability. For most conventional lenses, surface wettability was largely dependent on surface-active ingredients, and reduced significantly after depletion of these surfactants.
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