View Full Version : optical prescription over the years
Dear all,
Am due to commence training shortly. I currently just pass the Class 1 unaided - my question is, how much does eye power deteriorate every year? Is there a set pattern? I'm worried about losing my licence, say 5/10 years into flying because my prescription exceeds the limits.
Isn't the limit +/- 5 dioptres? Is this a lot of leeway or what could be easily clocked up by gradual reduction in my optical standards over 5/10 years?
Thoughts if you please.
RSE.
effortless
17th Nov 2005, 13:17
5 dioptres is a lot. My eyesight hasn't deteriorated that much since an RAF medical in 1968 (which I only just passed). My vision is currently just over -1 in each eye and that is with an astigmatism. There are so many factors that it is hard to give an answer. This said, if you use contacts, your vision deteriorates less over time. My mum didn't change her prescription for thirty years.
Vee One...Rotate
17th Nov 2005, 14:03
Remember that the renewal standards are less stringent than the intitial ones. I'm sure there's little to worry about.
V1R
In middle age, (mid 40's?) the focus mechanism of the eye tends to stiffen somewhat.
This is called a loss of 'accommodation'.
Its why many folk, Mr PM Blair included, find themselves needing reading glasses around that sort of age.
As you can see when shopping in the supermarket, non-prescription reading glasses tend to be in the range +1.25 to maybe +3.0 dioptres.
One of the inferences that I draw from that is that few people in the general population notice/bother about an error of less than 1.25 dioptres...
Cheers guys;
effortless - "This said, if you use contacts, your vision deteriorates less over time" - why is this?
...and don't contacts mean a lower strength prescription anyway as they rest on the eye rather than in front of it?
V1R - what are the renewal standards off the top of your head?
WDH - "One of the inferences that I draw from that is that few people in the general population notice/bother about an error of less than 1.25 dioptres..." - but we have to bother with it because the CAA says so don't we?!
Just checking...maybe being a hypochondriac but the effort and money required mean I need to check all this!
RSE
effortless
17th Nov 2005, 17:14
effortless - "This said, if you use contacts, your vision deteriorates less over time" - why is this?
The lack of air gap has something to do with it. Also if you have an astigmatism, a hard lens will keep your cornea in shape.
Flyin'Dutch'
17th Nov 2005, 20:43
Between the age of 18 and 40 there is usually very little change in correction needed for those that wear glasses.
Beyond that most people with myopia move a bit towards the less correction needed and often manage reading without any correction, where their previous 'uncorrected' brethren will have to start wearing reading specs.
As said on here before, renewal limits are a lot less stringent than initials. -8 for myopia rings a bell.
Vee One...Rotate
18th Nov 2005, 09:03
rse,
As said on here before, renewal limits are a lot less stringent than initials. -8 for myopia rings a bell.
Rings a bell too - definately the limit last time I checked. Double-check on the CAA's website to be sure though.
One quick aside - I've often heard myopia can "improve" a little in later years. Is there generally an up/down trend for astigmatism as well?
Cheers,
V1R
Professor Plum
18th Nov 2005, 11:28
The renewal standards for the eyesight test can be found Here (http://www.caa.co.uk/default.aspx?categoryid=49&pagetype=90&pageid=531)
The info you need is about three quarters of the way down the page.
captplaystation
24th Nov 2005, 12:19
Seem to remember that less stringent standards were being mooted for renewals ( I believe the dog had to be 6/6 without correction though!) and I seem to remember the CAA could at their discretion issue a medical "out of limits" in exceptional circumstances i.e. you had been flying 20 years & hadn't bumped into anything yet;sounded like common sense to me.I was told I was just within limits when I did my initial over 30 years ago, and even though I am more "bats eyes" than "cats eyes" I still scrape through.There are many health issues much more likely to catch you in later life than this,wouldn't fixate on it too much.