[New approaches in topical drug administration and treatment of the dry eye].

The collagen shield is a contact lens-shaped collagen matrix that can be impregnated with a drug during hydration or manufacture and then, when placed on the cornea, acts as a reservoir, dissolving slowly and releasing the drug over time. This new ocular drug delivery system has proven useful in the treatment of corneal infections and the prevention of graft rejection. The lubricating effect of the dissolving shield matrix may palliate dry eye symptoms, but the shields are not useful as a treatment for keratoconjunctivitis sicca because they must be applied in the physician's office and they are not transparent. A new formulation of collagen and cetyl alcohol particles suspended in a methylcellulose vehicle (Lacrisomes) is being developed to relieve symptoms in dry eye patients. A similar system, with the addition of therapeutic agents during manufacture (Collasomes), is being tested for drug delivery to the ocular surface. The advantages of both of these systems would be their ease of application and minimal interference with vision.