"DOCTOR AT SEA" a monthly Column in The Islander Magazine
"I see no ships" - Eye conditions and ENG1
"I see no ships" is a famous misquote of Lord Nelson at the Battle of Copenhagen in 1801 when his commander, fearing Nelson was suffering unacceptable losses, hoisted the signal to disengage. Nelson had lost his right eye on active service some years previously and said, as he raised his telescope to his right eye, "I have only one eye. I have a right to be blind sometimes. I really do not see the signal". He disobeyed the order and an hour later the enemy ships were destroyed and the day was his.
Monocular vision is still acceptable in a serving seafarer or one who loses an eye after starting life at sea but is not acceptable in new entrants. In general, the eyesight standard for new entrants is rather more exacting if only that the initial examination must be particularly careful to detect any problem which could have a major impact on someone’s career if picked up later.
Eye testing includes checking visual acuity and colour vision to establish fitness for lookout or for other duties, as appropriate. Lookout duties are carefully distinguished from watchkeeping duties which is simply the nautical term for shift working.
The familiar letter chart (Snellen test) is used for visual acuity and, for lookout duties, it is necessary to reach 6/6 (you can see at 6 metres what you should see at 6 metres) with or without glasses/contact lenses with at least one eye. With unaided vision you should be able to read the top letter on the Snellen chart (6/60 - that is, you can see at 6 metres what a normal person can to see from 60 metres!). This is to ensure basic safety if the glasses or contact lenses are lost or damaged. Spare sets of visual aids, spectacles or contact lenses, must be carried.
Laser refractive surgery is becoming popular and is generally very successful but distortion on distant point images may take some time to settle down after treatment. The MCA stipulates candidates are temporarily unfit for lookout duties for 6 months after surgery.
The visual acuity standards for engineering, catering or other duties are less exacting but this is less applicable in yachting with smaller crew numbers and inevitable multi-tasking compared with, for example, merchant vessels or cruise liners.
The commonest form of colour defect, affecting about 5% males but rare in females, is an inability to distinguish between red and green which are the colours historically adopted for oil navigation lights and which remain the colours in use. The problem is genetic and permanent and very rarely develops later.
Ishihara plates (numbers built up from coloured dots) are used as the initial test and it is essential to have normal colour vision for unrestricted lookout duties. If fitness for lookout duties is crucial for someone who fails the Ishihara test, the MCA offer a Holmes Wright B Lantern Test in the UK – this lantern test simulates navigation lights in a dark room and is the definitive test. There are less demanding but adequate colour matching tests for occupations needing some colour appreciation such as electricians or engineers.
Serving seafarers whose colour vision problem has come to light later can be issued with an ENG1 but may be restricted from “solo lookout duties” or may be “only fit for lookout during daylight hours” or perhaps “not fit for solo lookout duties at night” There is less flexibility for new entrants with colour vision problems and, whilst this is much less of a problem in other shipping sectors, it is a potential glass ceiling on career prospects amongst smaller multi-tasking crew members as found in yachting.
Dr Ken Prudhoe, MCA Approved Doctor, can be contacted at Club de Mar Medical Centre, Palma de Mallorca. Tel: (+ 34) 639 949 125.