Abstract
Abstract: :
Purpose. To describe design elements, features, and functions of a wearable microdroplet dispenser that serves as a programmable artificial lacrimal gland for adding aqueous component and drugs in precise dosages to ocular surfaces. Methods. A microdroplet generator, disposable fluid delivery tube and reservoir, and battery powered microprocessor are incorporated into an adjustable cover attached to eyeglass frames. The system is free of wires leading to shirt-pocket or belt-mounted fluid or power supplies. Sub-microliter sized droplets of balanced saline are projected to ocular surfaces, e.g. in groups of 500 microdroplets every 20s. Combinations of droplet counts and delays range from 1-5000 drops and 5 to 500s--programmed to 10 micro switch positions. Results. Aqueous component can be programmed for delivery to ocular surfaces at a rate from <1µl to 12 µl per minute. Individualized adjustments steer droplets around eyelashes or narrowed fissure between eyelids to land on bulbar conjunctiva. The microdroplets are below body temperature and are felt as a coolness on ocular surfaces. Risk of injury from accidental touch is low since the delivery tube is designed to be non-contacting and is made of soft plastic. Reservoir volume is sufficient for several days and batteries last for weeks. Conclusions. A self-contained, miniaturized microdroplet dispenser delivers microdroplets to completely replace lacrimal gland output several times over. Fluid volume and frequency are adaptable to individual tear drainage and evaporation rates. The precise, steady application of balanced saline maintains a consistent tear layer volume. Several severe dry eye patient categories may benefit from using the programmable dispenser for aqueous addition or osmolarity control (Sjögren's, Bell's Palsy, and post-surgical). Non-dry eye applications are discussed, such as drug delivery for intensive, sustained antibiotic, anti-inflammatory, or antioxidant therapry, and modification of ocular surface composition.
Keywords: cornea: tears/tear film/dry eye • lacrimal gland • aqueous