been reported that many of the same drugs and eye drops used to treat particular eye diseases do, in fact, result in systemic side effects that could possibly be minimized or limited due to a slower, more sustained release of the drug. the systemic side effects of glaucoma medications such as latanoprost increased heart rate resulting in cardiac arrhythmias, bronchoconstriction, and hypotension. these complications could be life-threatening. some other drugs that help to reduce the effects of glaucoma in the eye result in vomiting, diarrhea, tachycardia and bronchospasm. it has been found that some drugs delivered in the form of eye drops are highly toxic to children since their total body volume and tissue volumes are much lower than that of an adult for which the drugs are intended for use. in this case, some parents are not aware of these implications and could use the same drug they would use to help treat their children's bacterial infections in the eye. moreover, some drugs administered to the eye have been shown to result in cardiac depression and propagation of some disorders such as asthma. with continued research in this area, it has become known that skin irritation, itching or rash are commonly associated with drugs used to treat ocular bacterial infections. ocular disorders there are currently four main ocular disorders that have been heavily investigated and have shown success with using contact lenses as possible devices for molecular drug delivery. bacterial infection figure 5.0 - example of zero-order release kinetics (y = % of drug released from contact lens; x = time (days)) the drug release rate is extremely important in treating many diseased states of the eye, bacterial infections being one of them. ciprofloxacin and norfloxacin are drugs that are normally used to treat bacterial infections of the eye. it is of utmost importance that these drugs stay in the therapeutic window for an extended period of time in order to be fully effective and kill bacteria. to keep the specific drug in the therapeutic window using eye drops the topical must be applied approximately every 30 minutes in order to be fully effective. having to apply eye drops every 30 minutes would be nearly impossible for anyone and is not the ideal mechanism by which to deliver such drugs to the eye. researchers have gathered data to support the idea that silicon-based contact lenses with ciprofloxacin could release the drug in the therapeutic window for approximately one month. ana guzman-aranguez et al. also confirmed that the contact lens used also retained important properties such as transparency, oxygen permeability, mechanical strength, and zero-order release pharmacokinetics. figure 6.0 - cornea epithelium corneal injury many factors can result in corneal injury and cause the deterioration or death of cells that make up the cornea of the eye. the epithelial cells that make up the cornea are important in order for normal vision. these cells play a role in creating a physical environment that can correctly bend light rays to help project images to the retina of the eye. there have been successful human clinical trials with using scls infused with epidermal growth factor (egf) that showed increased rate of healing of the epithelial cell layer of the cornea. figure 7.0 - glaucoma complications glaucoma glaucoma is the leading cause of blindness in the world and is a progressive and irreversible disease of the eye. a poly(lactic-co-glycolic acid)-based contact lens was shown to release latanoprost at a sustained release rate of up to a month in animal models by ciolino et al. at harvard medical school and massachusetts institute of technology. latanoprost is one of the drug interventions used to treat patients with glaucoma, generally in the form of topicals such as eye drops. figure 8.0 - dry eye syndrome complications dry eye more than 50% of all contact lens wearers report that they experience dry eye. in order to help combat this issue and be assured that this does not occur in people that will one day be using drug eluting contact lenses, it is important to make sure that this complication is highly investigated. however, these investigations will not only be beneficial for contact lenses as drug delivery devices, but it will also have positive implications on contact lens wearers who use lenses for vision correction and appearance. index: scientific terms in context of ocular drug delivery term definition ph responsive system the ability for a biological system to undergo changes that promote activity, inactivity, release of compound(s), or degradation as a result of changes made in the ph of the microenvironment of a certain system nasolacrimal drainage drainage of particles/fluids into the body via the tear (nasolacrimal) duct systemic of or relating to the entire body zero-order kinetics release of a drug from a delivery device at a singular and constant rate the entire time of release timolol (1--3--2-propanol) norfloxacin (1-ethyl-6-fluoro-4-oxo-7-(1-piperazinyl)-1,4-dihydro-3-quinolinecarboxylic acid) ketotifen (10h-benzo(4,5)cyclohepta(1,2-b)thiophen-10-one, 4,9-dihydro-4-(1-methyl-4-piperidinylidene) polyvinylpyrrolidone hyaluronic acid latanoprost (isopropyl-(z) 7cyclopentyl]-5-heptenoate)