Extended Release of Macromolecular Comfort Agents from Silicone Hydrogel Contact Lenses
Type of Degreethesis
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Contact lens induced dry eye (CLIDE) affects approximately 80% of contact lens wearers. Extrapolating to the world wide population of 300 million contact lens wearers, there are approximately 200 million wearers who express dissatisfaction with their current lenses. The design of contact lenses have evolved to promote high oxygen diffusion (Dk) to promote comfort and ocular health. Since the advent of silicone hydrogel lenses in the market in the later 1990’s, silicone hydrogel lenses have dominated the lens market in recent years, making up 60% of all lens fittings in the United States in 2009. Several brands are approved for 30 day continuous, extended wear, making these lenses very popular with consumers. However, most lens wearers still express dissatisfaction with their lenses due to CLIDE-related symptoms. Controlled drug delivery methods applied to soft contact lenses deliver have been shown to deliver macromolecular comfort agents to the eye. Yet controlled drug delivery from silicone hydrogels has yet to be shown in silicone hydrogel contact lenses. This represents a large technology gap. To fill this unmet need, we have designed novel contact lenses (based on Lotrafilcon B silicone hydrogels), which are capable of controlled delivery of 120 KDa hydroxypropyl methylcellulose (HPMC) through application of biomimetic molecular imprinting. This is the first instance controlled and tailorable release of ocular therapeutics from a silicone hydrogel lens. By adjusting the ratio of acrylic acid (M) to HPMC (T) in 100 μm thick lenses, the rate of HPMC delivery can be tailored to deliver 1,000 μg HPMC for up to 60 days. By adding divinyl functional monomers (xLer) to the Lotrafilcon B mixture, significant control was granted over swelling, optical clarity and modulus.