Medical device developer Corinthian Ophthalmic, which is developing a device that would improve drug delivery to the eye, has raised $1.6 million, according to securities filings.

The offering, a mix of debt and other securities, could go as high as $4.9 million. Filings show that 13 investors have put money into the latest securities offering so far.

Raleigh-based Corinthian’s device is intended to replace the traditional eye dropper, which can trigger tears that wash away the medicine. Investors listed on the securities filing include Fred Eshelman, founder and former chairman and CEO of Wilmington, North Carolina clinical research organization PPD and Ernest Mario, who was on the PPD’s board of directors.

The latest fundraise follows a December offering that raised $775,000 from 10 investors.