New light on 300-year-old puzzle about sight

 The puzzle looks simple and elegant: Imagine a person blind from birth who abruptly gains sight in adulthood. Immediately after the onset of sight, would the person be able to visually discriminate between objects that were previously identifiable only by touch? Known as Molyneux query, it dogged philosophers and neuro-scientists since AD 1688 when it was first thought of by Irish scholar William Molyneux. Nobody knew whether a congenitally blind would be able to correctly distinguish between a chair and table after they gain their vision from corrective procedures.

While successive generations of neuro-scientists tried to find out the answer, philosophers consider it as one of the most-profound questions facing the mankind.
Enter Project Prakash — a seven-year-old initiative run by the Shroff Charity Eye Hospital in the capital in collaboration with Massachusetts Institute of Technology with US funding — in which congenitally blind village kids are screened to identify those whose blindness can be treated. More than 700 children have been treated so far in this project free of cost.

Prakash team had an opportunity to answer the Molyneux query by working with congenitally blind individuals who received sight restoration surgeries. “In studying their post-operative vision, we found answer to the 300-year-old puzzle,” MIT professor Pawan Sinha, who started the project, told Deccan Herald.

Five children—four boys and one girl—between 8 and 17 years of age were selected for the experiments. Prior to treatment, they were only able to discriminate between light and dark and two of them could determine the direction of light.

The four boys underwent cataract surgery while the girl was provided with a corneal transplant after which their vision was restored partially. The researchers conducted experiment with these five before and after their treatment. “Our results suggest that the answer to Molyneux question is likely negative,” researchers from MIT, Shroff Eye Hospital, Indian Institute of Technology, Delhi and Tilburg University in the Netherlands reported in the latest issue of the journal “Nature Neuroscience.”

The initial acquisition of vision is not accompanied by visual recognition of objects known by touch. But that ability is acquired within days of recovery of vision, Sinha said.

The outcome is significant. “It shows 40-50 pc vision can be restored in congenitally blind even at a late stage which goes against the conventional wisdom,” said Dr Suma Ganesh.

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