Warby Parker isn't the only start-up disrupting the vision space. GrayBug, a company that recently won the Invest Maryland Challenge in Baltimore, Maryland, is revolutionizing drug delivery and treatments for the eye. 

GrayBug started after three professors at the Wilmer Eye Institute at Johns Hopkins University--Justin Hanes, Peter Compochiaro, and Peter McDonnell--developed two treatments to help patients who suffer from age-related macular degeneration. The three founders determined that the fastest way to get their innovations to the public was to start a company.

Age-related macular degeneration is a leading cause of blindness in adults 65 and over, with over 20 million cases in the U.S. and Europe. GrayBug estimates that market is worth around $4 billion worldwide.  The typical treatment includes receiving injections in the eye every one to two months. GrayBug claims its sustained-release drugs may reduce the number of injections needed to just twice per year--a potential boon for the tens of million patients who describe the experience as disturbing and painful. Other treatments for blinding ocular diseases, such as glaucoma, are in the works. 

So far, the company has three full-time employees and more than a dozen advisors. A GrayBug spokesperson declined to offer specifics about the company's valuation or annual revenue, but says that  Baltimore's thriving start-up scene helped drive the company's early success. Not only does GrayBug enjoy easy access to a number of prestigious universities and federal institutions, but the Maryland Biotechnology Center and BioMaryland have also extended support. 

In recent years, Baltimore has become a thriving hub of health innovation. The state of Maryland ranked No. 2 for science and technology assets (behind Massachusetts), according to the Milken Institute. One of the foremost biotech companies, MedImmune, which is based in Baltimore, developed the FluMist nasal spray influenza vaccine. Other innovators include Zyngenia, a biotech company, and MedImmune's venture capital arm, which invests in health start-ups.