If the Fog Clears...

Wednesday 11th August 1999 is a day few of us will forget – a total eclipse will be visible throughout Cornwall and the Isles of Scilly lasting approximately 2 hours as the moon travels in front of the sun and darkness spreads from the west. The period of totality will last approximately 2 minutes.

Viewing the sun is dangerous without pin hole cameras or solar viewers, except during the period of totality. Solar exposure for more than 90 seconds exceeds the threshold for photo-chemical retinal damage. The vision may immediately deteriorate although some recovery is possible up to six months after the event. The patient may continue to have problems with distortion or abnormal colour perception indefinitely. There is no treatment of any kind.
Patrick Moore tells us that some telescopes are sold with "sun caps", which, it is claimed, make direct viewing safe, and points out that this is not the case.

The British Astronomical Association advises that the eclipse should only be viewed through special filters such as aluminised Myler filters conforming to EC directive 89/686/EEC or through welder’s glass rated number 14 or higher. Do not use scratched filters or single pin hole filters.

Place the filter over your eyes before looking at the sun and remove them only after looking away. Be alert to the brilliant disk at the end of totality – it is surprisingly sudden – immediately look away and use filters once more.

The eye department is not doing any routine NHS work during eclipse week and will be available to provide GPs with diagnostic support with extra staff in clinics at Falmouth, Penzance, Bodmin and Truro in the week following the eclipse. We are to counsel patients that central vision and colour perception may remain impaired and refer to eye clinics on a semi-urgent basis. Patients from out of county will be similarly counselled and advised to seek ophthalmic advice on returning home.


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