As many as seven million units of the Apple Watch have been sold since its launch, but has failed to generate the same effect as the iPhone, which dominates the smartphone market since its launch in 2007. But the designer of the watch believes the wearable will not take more than a few years to become a game changer.

In an interview with AFR Magazine, Marc Newson, who played a key role in designing the Apple Watch along with chief designer Jonathan Ive, said: "As far as I'm aware, it's been enormously successful however you gauge it. The point is, it's the beginning of something. I think people, consumers or analysts, whoever, are so impatient. Everyone wants immediate, instant recognition, instant understanding.

"Look at the iPhone: it was a game-changing thing. And I believe that this product – for many, many reasons people are not aware of because they haven't thought ahead or they just don't know – will become a similarly game-changing thing. In five years' time I have absolutely no doubt this will be right up there." Newson highlighted the health and fitness features of the watch and the ability to "liberate" users from their mobile phones.

Apple CEO Tim Cook did not spell out the sales figures of the Apple Watch during company's fourth quarter earnings announcement. He clubbed the device into a new category called "Other Products" that includes iPod, Apple TV, Beats headphones and speakers and other accessories. However, Cook did note that the sales were more than the previous quarter.

Rumours are already swirling about the sequel to the watch - Apple Watch 2 – which, according to financial service firm Cowen and Company, will come in a thinner size and have features to improve performance. It is expected to be launched in mid-to-late 2016.