+/-5 limit refers to DIOPTRIES or to "objective refractive error" measured by device?
 

Dear friends,

I would like to know whether the limit of +/-5 refers to "real" DIOPTRIES you have on your glasses or to the "objective refractive error" which is measured by the measuring device (green dot).?

Please help

Thank you
Blanik9715

you can mail me to: [email protected]

anybody know?
 

Does anybody know the answer to this one? sounds interesting

Hello,

I'd say it has to be the objective measurement as I'm a recent contact lenses convert and my glasses had a stronger prescription (just) due to the lenses being that bit further away from the eye (0.25, 0.5) - with my contacts it's 0.00 and 0.25.

Good question though - I seem to be remember a phrase something like "correction must not exceed blah blah blah" on the CAA's website indicating that if you just fell outside of limits with spectacles (i.e. they corrected too much), you might get away with contacts (less correction required). This wouldn't be a measure of objective error though, only a measure of how much correction you need with a certain device...

Not sure about this one...

V1R

Sorry not to have answered this one before but had difficulty getting into this thread.

They determine the refractive error by doing the vision test. Otherwise you could wear a (suboptimal) correction and scrape through.

For instance your true error is -6 you correct with lenses so that you can just manage the 6/6 (20/20) line. For that you need say a -2 correction and you would be fine.

Nope does not work like that.

One goes by the correction needed to get best vision.

FD

As a pilot facing the initial Class One and someone who admittedly knows very little about optics, does that mean that my -4.75 glasses prescription and -3.75 contact prescription are pretty nonsensical? It's bloody hard trying to work out whether you conform to the CAA's criteria.

Regardless of what strength my glasses or contacts are, does this mean that my eyesight is measured on other grounds instead?

Please explain! Your answers will be received with gratitude.

Cap'n Ratpup

When I saw the CAA last year they took my GLASSES script as my refracticve error measure for their records. Even though my contacts (which I wear every day ) are lower

Glasses +5.75 in L/R
Contacts +5.0/5.5 in L/R

Hope this helps Herr Captain;)

Refractive error
 

The maximum refractive error is measured starting with uncorrected vision.

When you use contactlenses you shouldn't wear them for 48 hours.

Your refractive error is the strenght of correction in diopters you need to get 20/20 vision.

It's just a very simple eye test wich every doctor or optometrist does.

Any form of influencing you're uncorrected vision will leed to failure.

So don't use OK lenses or refractive surgery, without telling. Because they will find out, and lying is considered a serious offense.

Thanks Irish. I thought that the CAA's limits were +/- 5 dioptres. How did you get away with your eyesight?

final clarification ...? pls answer
 

Hi everybody,

thank you all for your replies to my post. Anyway, I didnt get the meaning of some of the replies here..

Finally, does Limit / Refractive Error refer to:

glasses / contacts (whichever is LOWER)

OR

"objective error"= device measurement (by focusing your eye on a GREEN CIRCLE or DOT )



just for final clarification...

Thank you again very much for your help

Boris = blanik9715, Slovakia, EU

[email protected]

Have had problems with the reply box on this thread before and now only just managed to get through again.

To answer your question:

They check your refraction by sticking the lenses on the test frame.

The method you descripe uses light projected into the eye and checking the refraction by looking into a machine.

That is used for people who can not do the method above or little children and is not used to establish visual acuity (ability to see)or refractive error (strength of lenses needed) for aviation medicals as far as I know or have come across.

HTH

FD

Wearing weaker prescription than your refractive error
 

If you can meet the required standard of visual performance whilst wearing an amount of correction that is within the prescribed limits then why isn't that good enough ?

The fact that I can achieve an even better standard with additional correction shouldn't matter - provided I meet the requirements for Class 1 that should be sufficient.

Seems so unfair. :mad: