Ophthalmology has long been a bright spot for venture investors given the potential market size, health care burden, and high unmet medical need associated with many eye diseases. Based on a recent analysis by Start-Up magazine, there is no sign that trend is diminishing. Using Elsevier's Strategic Transactions database, Start-Up found that private backers have poured nearly $1.8 billion into 58 ophthalmology start-ups since 1999, with the money split nearly 50/50 in terms of device and drug investments. This trend is likely to accelerate as a number of new acquirers emerge to play in what was once a niche area.

Acucela is developing oral compounds that can possibly slow or stop vision loss caused by dry age-related macular degeneration. Its lead candidate is a small-molecule inhibitor of an enzyme called RPE65, known to be involved in the build-up of A2E, a toxic vitamin A by-product that is implicated in AMD.

Fenretinide, Sirion Therapeutics' lead candidate, targets the pathway by which Vitamin A gets into the eye and becomes part of A2E, the protein complex that scientists consider a bad actor in AMD. Intermediate analysis of fenretinide Phase II data showed that patients taking the compound had slower growth of lesions than those given placebo, and that trend increased over time.