Customized Contact Lens Treatments for in-the-Eye Medication

Hydrophilic polymer (polymacon alphafilcon-A) andsilicone-based (balafilcon-A) hydrogel contactlenses before and after surface modification byradio-frequency glow-discharge treatment (RFGDT)were used to monitor methylene blue/silver nitratedrug-surrogate uptake and elution. Infraredspectroscopy revealed modified absorption peaksaccordingly. Energy-dispersive x-ray (EDX) analysisand inductively coupled argon plasma atomic emissionspectroscopy (ICP) confirmed silver lens depotconcentrations and were employed to measured eluateconcentrations while visible spectrophotometry andICP spectrometry monitored methylene blue and silverelution rates in static versus simulated eye-blinkingconditions. The conclusions reached are that (1)initial drug uptake of surface modified lensesincreased in this order: polymacon < alphafilcon-A <balafilcon-A lenses; (2) drug release rates of thepolymacon and alphafilcon-A remained unaffected bythe RFGDT; (3) increased release rates occurred fromthe RFGDT-surface-modified balafilcon-A lenses; and(4) dynamic forces increased the release rates forall contact lenses.