Second Sight Medical Products Inc. has entered into a stock purchase agreement with Gregg Williams, chairman of the company’s board for the purchase of nearly 2.5 million shares which will yield $4 million in proceeds to the company.

The funds will support the Sylmar medical device maker’s projects to give partial vision to blind patients. The company is working on the Orion Cortical Visual Prosthesis System and the Argus 2s implant.

Williams bought $10 million in Second Sight shares in May to fund the company’s research.

“We would like to again thank Gregg for his continued support,” Chief Executive Will McGuire said in a statement. “This incremental $4 million investment allows us to continue to advance our important initiatives for Orion and Argus 2s. We are pleased with our progress to date and look forward to reporting future results, including data from the six-person feasibility study that we are conducting at Ronald Reagan UCLA Medical Center and Baylor College of Medicine.”

“This investment in Second Sight reflects my commitment to advancing the Orion technology and my confidence in our ability to develop this groundbreaking technology into a marketed product,” Williams said in a statement.

The company announced the transaction Monday. Shares of Second Sight (EYES) closed Tuesday up 4 cents, or 2.5 percent, to $1.64 on the Nasdaq.