UCL News


UCL in the News: Lookout's lenses blamed for sea accident

19 April 2007

Photochromic lenses, which change from light to dark depending on the amount of light they are exposed to, may be inappropriate for use by lookouts on the bridge of merchant vessels, a UK marine accident investigation report has revealed.

The report into the disappearance of the sailing yacht Ouzo, which was released last week by the UK's Marine Accident Investigation Branch (MAIB), found that the night vision of a user of photochromic lenses could be reduced by up to 20 per cent. …

The lookout on the 177-m-long ferry had not seen the yacht until it was very close ahead and the yacht had not shown up on the ferry's radars. The officer of the watch tried a last-minute manoeuvre to avoid the yacht and believed that he had been successful. …

Following the accident, the MAIB had the lookout's eyes examined once again and his prescription lenses were found to be correct. His photochromic lenses were sent to the UCL Institute of Ophthalmology to assess if they might have had an adverse effect on his night vision.

The institute's report concluded that the optical transmission of the lenses was no more than 80 per cent efficient and, taking into account all of the other known factors, was probably less at the time of the accident. … The institute's report concluded that the other photochromic lenses tested showed significant reductions in the amount of transmitted light, but the lenses that had been worn by the ferry's lookout were significantly inferior to other commercially available lenses.

The institute said this indicated manufacturers have improved the performance of photochromic materials or the performance of photochromic glasses is reduced with time, with the latter being more likely. …

Selva Kumar, 'The Business Times' (Singapore)