Novartis has abandoned a 2016 goal to start testing its autofocus contact lens on people, though it said the groundbreaking product it is making with internet giant Google is "progressing steadily".

"It is too early to say when exactly human clinical trials for these lenses will begin," a spokeswoman for the Basel-based drugmaker said in an email on Friday.

"This is a very technically complex process and both sides are learning as we go along. We will provide updates at the appropriate time," she said.

Novartis Chief Executive Joe Jimenez said last year his company's Alcon eye care unit was on track to begin testing in 2016.

In 2014, Jimenez said he hoped the lens would be on the market in about five years.

Novartis and Google joined forces two years ago to develop two kinds of "smart" contact lenses: An autofocusing lens for people with presbyopia, or far-sightedness, and another for measuring blood glucose levels in diabetes patients.

The lenses are now being developed with Alphabet Inc.'s life sciences unit Verily, which was carved out from Google in 2015.

Measuring blood sugar via the eye could allow diabetics to stop having to prick their fingers, while an autofocus contact lens would help people whose ability to focus is impaired when their eyes age.

It is unclear when testing for the diabetes lens will start.

Since the partnership with Google was launched in 2014, Alcon's sales have slid and its leadership team has been replaced.

New division head Mike Ball has been tasked with halting the revenue decline in advance of a possible sale of the unit.

But Novartis said that did not bar investment in innovative projects such as the lens effort with Google.

"Advancing innovation such as the smart lens technology, is a key part of Alcon's growth strategy," the spokeswoman said.

"The 'smart lens' technology has the potential to transform eye care and further enhance our pipeline... in the contact lens and intraocular lens space."