Glaucoma is the second leading cause of blindness worldwide. (Quigley & Broman, 2006) In undeveloped countries, both limited detection and inadequate treatment contribute to the high prevalence (20%) of blindness from glaucoma. (Leske et al., 2004) Yet, even in developed nations, where treatment is available and accessible for most of those who have been diagnosed, treatment adherence and persistence remain formidable obstacles to forestalling glaucoma progression. (Schwartz and Quigley, 2008) In the last few years, researchers have shown that medical treatment can delay or halt the progression of glaucoma, and that early identification and treatment are vital to preserving vision. (Kass et al., 2002; Kass et al., 2010; Musch et al., 2009) Despite the characterization of glaucoma as a degenerative neuropathy of the optic nerve, lowering intraocular pressure (IOP) by regulating the volume of the aqueous humor remains the mainstay of treatment. The Advanced Glaucoma Intervention Study (AGIS) was one of the first to demonstrate that lowering IOP protects against visual field deterioration. (AGIS, 2000) Subsequently, the Ocular Hypertension Treatment Study (OHTS) revealed that topical medication can reduce IOP by 22.5% in those at risk of developing glaucoma, thereby preventing the onset of primary open angle glaucoma (POAG) in the majority of at-risk patients with elevated IOP. (Kass et al., 2002) Several studies demonstrated that early treatment produced better visual outcomes than when treatment was delayed. (Musch et al., 2009; Kass et al., 2010) Paradoxically, however, this is the most challenging time during the course of the disease with regard to treatment adherence. Most patients are asymptomatic early in the disease, and if they do not perceive an immediate benefit from using their eye drops, they are less likely to use them. (DiMatteo et al., 2002) Drops are the liquid equivalent of a pill, and measure a discrete quantity of medication in a specified volume, as a means of delivering the prescribed amount of drug. While drops are a convenient method for specifying dosage, the fluid nature of the liquid state implies that drops are more easily divisible than a solid pill. Whereas effort and intention are required to subdivide a pill, drops less readily retain their integrity, allowing volume to be unintentionally sacrificed. Indeed, several variables can affect the size of the drop that is