Medical history was created in the city on Sunday when an ophthalmologist operated on a cataract through a 700-micron incision, arguably the tiniest ever used in phaco-surgery in any part of the world.

To put the size of the incision into perspective, it was as wide as the tip of a .5 mm ballpoint pen. The surgeon, Amar Agarwal, claimed the operation made India a global front-runner in the development of surgical procedures and techniques for cataract removal.

The surgery marked the launch of a new technique, microphakonit.

About 300 leading ophthalmologists from all over the country watched on a giant screen as Agarwal performed the microphakonit on an aged patient with advanced cataract.

An operating theatre of BB Eye Foundation, on Sarat Bose Road, was the venue. The operation was telecast live to the participants of a daylong workshop on eye surgery. They were seated in the conference hall of the institute.

?The surgery was a milestone in cataract removal and a feather in India?s cap. The technique used will set a trend. It heralds a new era in cataract surgery,? opined ophthalmologist Pradeep Kumar Bakshi, who watched Agarwal perform the operation.

Agarwal, who is based in Chennai, has invented a special phaco needle for the surgery. ?Larger incisions are generally used in phaco-surgery. The smallest recorded incision has so far been of 900 microns. Dr Agarwal should be lauded for improving on that. The incision is barely visible to the naked eye. The patient did not feel any discomfort after the surgery,? said ophthalmologist Partha Biswas, who is also the director of BB Eye Foundation.

In Calcutta and other parts of the country, micro-surgeries for removal of cataract are quite common. Incisions of about 10 mm are generally made during the operations. Phaco-surgeries using smaller incisions have also been attempted, but not of the order of 700 microns.

Patients undergoing microphakonit need not stay in hospital overnight. They can walk into clinics, get their cataract removed and get back to work immediately.

However, the new technique costs 20 to 30 per cent more than conventional phaco-surgery. Microphakonit typically takes about 15 minutes.

Experts expect the technique to catch on.

?We must give Dr Agarwal the credit he deserves. I have travelled all over the world. I myself do a lot of phaco-surgeries. This technique was, in all likelihood, used for the first time in the world on Sunday,? said eye surgeon Divyesh Shah.

The intra-ocular lenses used in the surgery were the rollable lenses that were injected through the incision.

About 10 million people go blind in India every year. Of these people, eight million are afflicted with cataract, stated Agarwal, who flew back to Chennai in the afternoon.