I think eye tests are free for everyone now.
As far as I know Specsavers also offer the same deal as Tesco

I also bought varifocals in Goa and I was not pleased either with the service or the specs. Used an optician in Calangute and thought the service was very rushed. Also another time used an optician in Panjim and was equally unimpressed.

Now have free eye test (over 60) in local UK town then send prescription to GlassesUK.com who supply glasses for a very reasonable price. I cannot actually remember price but they had a very wide range of frames and explain sizes etc so you can understand what you are ordering.

I later broke a lens and asked if they could replace it which they would do for £25. Sent glasses back to have it replaced and they replaced the frames as well. Incredible quick and efficient and friendly service. Far superior to my experience in Goa.

Also less hassle.

Although I love shopping in Goa, for me buying specs was a bad experience and if you buy them on the internet it is so easy.

Tried a few opticians over then years, Romanos, not impressed, poor quality,some new gaff in Mapusa, well overpriced.
Stuck with Eyesite on the Beach Rd. Candolim for the last 3/4 years.
Varifocal rimless with flexi titanium arms £105 including extra thin Kodak or Carl Zeiss lens.
If you want the thin lens dont leave it to late as they get done in Mumbai and usually take around a week to show up.
Same specs in hometown £450 so not a bad saving on my account.
P.S. the specs i'm wearing in my avatar :- varifocal reactolite were £80