By Daniel Lak BBC correspondent in Kathmandu

Dr Sanduk Ruit performing a cataract operation

Annual famines ended with the introduction of potato farming.

Sir Edmund Hillary's Himalayan Trust helped provide world class education and health services in her village.

Because of all these factors, Phiri's family is well off by Nepali standards.

But now - despite being physically robust and full of intellectual vigour - Phiri's world is severely restricted.

She can no longer see the changes around her, thanks to cataracts in both eyes.

"The left one has been black for four years," she says pointing to a permanently closed eye in a wrinkled face. "I lost sight in the other last year."

'Now I'll see my grandchildren'

It is a common problem in rural Nepal. Up to 70% of cases of blindness there are due to cataracts.

Phiri is one of the lucky Nepalis.

Phiri Sherpa had both her cataracts removed

"There can be no rich or poor, no children of a lesser god," says the centre's founder and medical director," Dr Sanduk Ruit.

"Everyone deserves good vision, and everyone deserves access to the best quality eye care."

That is why Dr Ruit and his fellow medical staff - all Nepalis or Tibetans - spend much of their time providing free or subsidised eye care at the centre or in a dozen or more field surgeries every year.

Hundreds of thousands of Nepalis and people from neighbouring countries have benefited from the work of the Tilganga surgical team.

One of them is 60-year-old Maya Devi, in for her second cataract removal in mid-October.

She and her family raised the $80 cost for the first operation and had the second done for free.

She was one of 30 patients treated in Dr Ruit's operating theatre that day.

Maya Devi had two cataract operations-one for free

"Now I'll see my grandchildren. They won't have to help me find my food anymore," Maya Devi told me.

The Tilganga's work doesn't stop at routine eye surgery.

Cornea donors

In the basement of the modern hospital is an even more state of the art facility, The Fred Hollows Intraocular Lens Laboratory.

The late Dr Fred Hollows of Australia was a friend and colleague to Dr Ruit and the two men shared the philosophy that drives the Tilganga centre.

In the laboratory, more than 300,000 tiny plastic lenses are produced by technicians in bio-safety suits.

Hygiene is crucial because export of lenses to Australia, Europe, Latin America and other countries provide much of Tilganga's income.

Poor patients need not pay for getting a lens from the laboratory.

A final example of the Tilganga Eye Centre's pioneering approach is found at Pashupatinath temple on the outskirts of Kathmandu.

Here, Nepali Hindus bring their dead relatives for an auspicious cremation.

And lately, Tilganga technicians have been increasingly successful in persuading orthodox Hindu families to donate the corneas from their dead relatives eyes before the funeral pyres are lit.

In a small room next to the sacred river Bagmati, Roshan Dhungana is carefully cutting the cornea from the left eye of a deceased elderly lady.

Her family stand watching, nervous at first but increasingly pleased that the simple operation does not harm the face of their loved one.

"It's marvellous," says the dead woman's son, "she still looks at peace and now her eyesight will live on."

Eye technician at Pashupatinath temple removes cornea from a dead woman

But Dr Ruit isn't complacent.

Eye problems don't go away. Blindness is still one of the most common aggravating factors of the cycle of poverty in places like Nepal.

"We have to keep doing this," he says, referring to the activities of the Tilganga Eye Centre.