The Medtronic and Bausch & Lomb-backed eye care medical device maker has raised $66m in a KKR-led round that took its total funding to more than $215m.

AcuFocus, a US-based, corporate-backed developer of medical devices to improve near vision, raised $66m on Friday in a financing round led by investment firm KKR, one of several recent deals for eye care companies.

Founded in 2001, AcuFocus is working on technology that uses a small aperture to ensure that only focused light rays reach a patient’s retina, meaning objects can be focused on more effectively. The cash will enable the company to commercialise its two main products.

Kamra is a corneal inlay that will help sufferers of presbyopia – a condition associated with aging where a patient’s ability to focus on close objects diminishes – restore their near vision without affecting their long distance vision, while IC-8 IOL helps improve vision across a range of distances for cataract sufferers.

Al Waterhouse, president and chief operating officer of AcuFocus, said: “This investment is a critical catalyst for the company.

“KKR’s confidence in our technology, along with its track record in successfully scaling businesses, will allow us to execute aggressively on growth plans to bring our disruptive small aperture technologies to full commercialisation.”

AcuFocus has now received about $215m in venture funding since it was founded and another $9.7m in debt financing over the past year, according to press releases, media reports and regulatory filings.

The company raised $38m in funding from investors including Versant Ventures, Three Arch Partners, SV Life Sciences, Pequot Capital, Carlyle Venture Partners and Accuitive Medical Ventures before securing $18m in a 2007 series D round featuring eye care technology provider Bausch & Lomb, Boston Innovative Optics, Versant, Pequot, Carlyle and Schroder Ventures.

Bausch & Lomb was joined by medical device maker Medtronic, Cowen Healthcare Royalty Partners, Versant, Carlyle Group and Accuitive Medical for a $65m round in 2011. Three years later Medtronic, Accuitive Medical, Versant, Carlyle, Cowen Healthcare Royalty and SV Life Sciences added another $21m.

AcuFocus is one of several eye care technology developers to have raised funding of late, though many have been developers of therapies for eye diseases. Precision Ocular secured $20.6m in July and Kala Pharmaceuticals raised $68m in April, while Clearside Biomedical raised $50m in its US initial public offering and GenSight filed for a $44m IPO in France.

In addition, eye disease gene therapy treatment developer RetroSense Therapeutics was bought by Allergen for $60m last week, two days before Lpath, the developer of an antibody treatment for the eye disease wet age-related macular degeneration, was acquired by surgical product developer Apollo Endosurgery.

Despite the deal activity the fortunes of the sector’s participants area to be largely mixed. Lpath was bought as a route for Apollo to get a public listing and had seen the price of its shares plummet from more than $90 in 2013 to $1.71 in mid-August, while GenSight had to cancel a US offering before opting to float in France. It is clear there are returns to be made in the space but it is far from a sure thing.