Esophoria requirements

[humpty]

I've just been to the optometrist for the eye test for a class 2 and came out with something I'm sure I didn't go in with! Apparently I've got esophoria of 9 whatevers at 6m and 10 whatevers at 30-50cm. I had a dig through the JAR regulations, and it doesn't seem to say anything for class 2 but for Class 1 they say the following:

"(f) An applicant with imbalance of the ocular muscles (heterophorias) exceeding (when measured with usual correction, if prescribed):
1Š0 prism dioptre in hyperphoria at 6 metres,
6Š0 prism dioptres in esophoria at 6 metres,
8Š0 prism dioptres in exophoria at 6 metres; and
1Š0 prism dioptre in hyperphoria at 33 cms,
6Š0 prism dioptres in esophoria at 33 cms,
12Š0 prism dioptres in exophoria at 33 cms
shall be assessed as unfit unless the fusional reserves are sufficient to prevent asthenopia and diplopia."

I then had a trawl through the CAA and in Class 2, they say "Any disorder eye muscle balance may need specialist assessment". For class 1, they say:

"Any degree of heterophoria (eye muscle imbalance) in excess of:
8D exo, 6D eso or 1D hyperphoria - measured at 6m
and
12D exo, 6D eso or 1D hyperphoria - measured at 33cms
will require further evaluation by an aviation ophthalmologist at Gatwick"

Looks the same except JAR mentions 'usual corrections' (which I assume means glasses) and 'fusional reserves' (which I'm not at all sure what it means at all).

What should I do? Looks to me like the options are one or more of the following:
- get specs to correct it (possible?)
- do exercises (possible? Brock/Brack string?)
- anything else?

I don't wear glasses now and don't particularly want to start unless I need to (laziness, not vanity!) If I do will I pass a Class 1 in Gatwick? What about the Class 2?

Any advice most welcome.

[Mark 1]

I have worse values than this (exophoria actually) and hold a class 2, but am outside the limits for class 1 (also on dioptre correction).

The CAA would normally advise you if you send them a copy of the optometrists report, without having to do the full medical first.

I think that prism correcting glasses would take a long time to get used to, I was advised that they wouldn't really help as the brain has already learnt to cope with the imbalance.

[FireDragon]

What you are describing is strabismus - a 'squint' - ie. one eye, (usually), either turns inwards, or outwards. Sometimes, people can have a very slight squint without knowing about it, while for others, it is very noticable cosmetically.

'Phoria' means that the eye(s) have an INWARD crossing tendency, which is controlled with effort.

Prism trials are normally carried out to determine the strength of prism required to correct the squint. (A prism can be slotted onto glasses, usually for trials, but can be ground in for a permanent solution).

I don't know what the CAA limits are, (correction - I didn't, until you duplicated them on your posting!), but they will be looking to ensure that: 1) You do not have, or are likely to develop, diplopia, (double vision) 2) You can attain fusion - i.e. both your eyes can look directly at an object, and your brain 'fuse' the two retinal images into one single image.

Obviously you were not aware of this condition, so that in itself would suggest that it is mild, so hopefully, you will be OK regarding the medical

FD

[humpty]

Now I'm really confused!

From my extensive background in opthalmology (several hours surfing!) I've picked up the following definition of strabismus: "Strabismus is synonymous with heterotropia and squint" from Indiana University. Now, the optometrists report specifically stated that there was no tropia but that there was phoria, so if the above definition is correct (and I'm applying it right) then it can't be strabismus... ???

Thanks for the input, I'll probably have a chat with the CAA or the AME and see what they say (copies of the regs tucked under my arm!).

[FireDragon]

Humpty

'Phoria' means that you have control over any squint; 'tropia' implies that there is no control.

FD

[FireDragon]

Just as an afterthought, in case I haven't explained myself very well.

ESO - means eye(s) turn IN (varying degrees)

EXO - means eye(s) turn OUTWARDS (again, varying degrees)

With 'phoria', you have the ability to control, or suppress, this squint, be it eso, or exo

With 'tropia', the eye stays turned in/out; - you cannot control it yourself.

With the type you CAN control, some people find, for example, they have no difficulty with their eyes during the day, but can find the control 'harder' to establish when they are tired: This is only one example, there are many more

FD

[humpty]

Gotcha - now I understand. Thanks. One final question: what is the stuff about fusional reserve? I think I understand that it's to do with the ability to bring the eye back in, is there any way to tell whether I have 'sufficient' fusional reserve?

OK, really the last question: the JAA regs talk about usual correction, does this mean I can get glasses to correct it, or is it just saying that if I do wear glasses for other stuff then they've got to be on when it's measured?

And that was the last question.

Promise.

For now!

[FireDragon]

Humpty

I presume you are refering to fusing vision. In order to eliminate any double vision, the brain has to process images from the two eyes, and make 'the complete picture'; this process is known as fusion. Sometimes, (especially if a squint is present), it can go wrong, leading either to double vision, or disregarded imput from one eye.

For example, if a child has an undiagnosed squint, cataract, etc. and if NOT treated before the age of about 7, the brain has problems fusing the vision, so instead 'switches off' the image from the bad eye. If this happens, binocular vision does not develop properly.

You will be tested for fusion and binocular vision at your medical, you will probably also be tested for accomodation (focusing up close). If you are found to lack bincular vision, this means that you MAY also have no depth perception either.

Hopefully, the problem you have sounds very slight, so none of the above will apply to you.

If I were you, I would go back to your optometrist, and ask for a detailed explanation, and find out what you do, or do not, have.

Alternatively, go and get just the vision part of the medical done at Gatwick

Good luck

FD

[humpty]

Thanks, am going to ME tomorrow, will see what he says.

[humpty]

Hee hee!

Doc gave me a class two and reckoned that I would be ok for a class 1 after a thorough going over with the Gatwick opthalmologists !!

One happy humpty! :)