India should review its use of mobile cataract surgery units after evidence shows poor results, researchers say.

It is estimated that 3.8 million people a year become blind in India due to cataracts. In total there are 8.9 million blind people in India - 24% of the world's blid population.

The Indian government introduced mobile teams as a way to tackle the problem as cheaply as possible, particularly in inaccessible rural areas.

The surgeons establish temporary operating services in improvised facilities.

As a result, the total number of cataract operations has increased from 1.2 million a year in 1991-92 to about 2.7 million in 1996-97.

A team from the Liverpool School of Tropical Medicine, UK, examined cataract surgery in the south-west Indian state of Karnataka.

They assessed the effectiveness of surgery carried out at three different locations. These were:

• Mobile government camps
• Walk-in services at a state medical college
• Satellite clinics to a non-governmental hospital

In government camps, almost half of the patients were dissatisfied with the results, and more than one third were blind in the operated eye.

Patient satisfaction was higher with treatment delivery provided in the other locations, and fewer patients remained blind.

Although camps are a low-cost option, the poor outcomes reduced cost-effectiveness.

Uncomplicated cataract surgery is usually 95% successful.

The researchers believe surgery may have failed in some cases because patients were suffering from other diseases of the eye that were overlooked.

The investigators, writing in The Lancet medical journal, say: "The government of India should review its policy for government camp surgery, and consider alternatives, such as transporting patients to better permanent facilities.

"India and other developing countries should monitor outcomes in cataract surgery programmes, as well as throughput."

In an accompanying commentary, Dr Gordon Johnson of University College London, UK, says that "ophthalmic surgeons should not be pressured to go for quantity at the expense of quality".