Stereopsis

[DuffyDuck]

Hey there.
I`ve got a medical question.
First of all my situation: I hold an glider licence and have some hundred flyinghours.
Now, i´d like to become a professional pilot. the problem is, that i have problems with stereoscopic vision. I do not have doublevision or even can´t see on one eye. both eyes are in very good condition, they just don´t work properly together due to a small strabism.
Do i have a chance to get a class I medical in europe or in usa?
the germans translated the jar-fcl3 very bad, so i probably won´t get one here.
I´ve also heard, that the faa don´t demand steroscopiv vision.
Thx for anwers, Duffy.

[WexCan]

I was failed today - have a strabismus that affects my depth perception and stereoscopic vision.

Best thing to do is get it checked by an opthalwhatever first - my vision is good but I was failed purely on the stereoscopic malarkey.

[Jimmy The Big Greek]

There is no sterescopic vision test requirement nor is there any standards or requirements set out in JAR-FCL.

Strabismus is ok as long as you dont have any double visions. You need to have deep suppression.

Find it very strange that you failed just because stereovision. I would definetely go to U.K and try there since they are more realxed over there.

[DuffyDuck]

Hi Jimmy.
Are you sure about this? A friend of mine (who hasn´t got stereovision) went to gatwick to get a class 2 medical. The eye doctor testet stereovision and first refused to sign. at the end, my friend got it.
I know the paragraph in the jar-fcl 3, it says there is no requirement. but on the other hand, they demand binocular vision!?:confused:

Thx for replyes, Duffy.

[Jimmy The Big Greek]

I think that the JAA needs to rewrite the part about eye imbalance.

They way it is now its not very clear.

Basicly I think it depends where you do the medical and with whom.
I think that differnent states and different doctors interpret the requirements differently.

The binoccular vision has different stages of stereoscopic vision.

One stage is the gross stereovision (tested with dot 4 worth ) and then there is fine strereoscopic vision (tested with TNO, Titmus).

As far as I know Jar-fcl only does the Dot 4 worth test and no test for fine stereoscopic vision. BUT it depends how each states looks at stereoscopic vision. I know that in Germany they are really stringent with strabismus and stereoscopic vision in Gatwick they send you to a specialist.

I have not done any medical in Gatwick but I have heard of guys with severe strabismus that has passed in Gatwick.

Good luck to you.

[Jimmy The Big Greek]

http://www.pprune.org/forums/showthread.php?t=55228&highlight=stereoscopic

[Flight my fire]

Hi there.

In the same situation as you.

Since you say that you don't have double vision. Your strabismus is an esophoria or an exophoria. You don't mention if your eyes are inward or outward.
Look at the standard they mention the limits of phoria. If you are within them, you should be ok. English are a bit more relaxed.
I 'm stilll searching for myself , and and infos i got are positive.

Yes try with Gatwick, one advice , if you don't want to have a bad surprise,
give them a call , and send them a letter explaining your situation , they will give you an answer and will let you know if you can hope being assessed fit.

Otherwise i got news from FAA doctors and pilots flying in Canada with that kind of problem.
If you don't see the stereopsis they have other ways to check if you are safe. As long as you don't have double vision you may have chances to pass the medical FAA or Transport Canada.

[Flight my fire]

One last precision on what i have mentioned above.

Esophoria, exophoria , hyperphoria, are strabimus for which the fusion of both eyes can be done without compensation. So no double vision. The reserve of fusion are ok.
Otherwise it's a squint ( aesthetically visible ) and double vision can be solved , with prisms worn to compensate and make the fusion possible.

So as long as your reserve of fusion is sufficient to prevent from getting any diplopia or double vision that should be ok.

One last info, there are in the US and Canada pilots who got surgical operation for strabismus, who were assessed fit even though they don't have perfect depth perception.

[DuffyDuck]

Hey flight, thank you very much. Jimmy as well.

@flight: some day ago, i went to an eye specialist. i don´t quite know how much my prism diopters are, but he told me i will never ever get doublevision!
if the prismdiopters are too much, will there be a posibility to correct it by an doctor? i know they cab´t do abything about stereovision, but how about prismd´s?
beside all of this, i´ve got a small rst of stereovision, about 100 angleseconds(thats what they call it in germany). i also can see the maddox cross! There is one test, you have to decide between 4 dots which one is a little bit higher than the others. i see 5 of them (out of 9 possible).
I´m quite worried about this prismdiopters, as i belive it was something between 5 and 10. (inward).

[Flight my fire]

Hi Duffy .

Hi Jimmy in the same time.


Yes to know how much prism diopters you have , you have to go an orthoptist. Who is specialized in eye muscle balance problem. Because it is not a vision problem but an eye muscle problem. But depth perception is a parameter in global vision especially for pilots and anybody whose work implies a good vision.
Call for for an appointment to get a full orthoptic check with tests. You will know at last your prism diopters.

In my case it is a bit different, i've got a myopia beside now stable. But a few years when it was increasing i had to wear prisms beside my myopia correction to compensate. 6 diopters prisms.
My strabismus is unvisible for people looking at me. When i wear my glasses i have no problem. I see normally, single not twice. But i'm not able to see all the stereopsis. Just a few ones.

JAR standards are not clear on that point , they mention no diplopia, no double vision , but they don't say if it includes prisms wearing.

As i mentioned in my previous post i had a few infos from FAA doctors and pilots with this problem. Pilots met on the net.
Jimmy explained it as well to me.

Because the axis of your eyes are not perfectly parallel you will never have a perfect depth perception. But if your problem is not too big you can improve it a little bit with orthoptic education. Exercises. In order to see a little bit better in stereo.

But it can't be solved.
There are two solutions , either wearing prisms or in the extreme case , surgery.
your case seems not to be too important so go to an orthoptist's and after if you are in the limits call Gatwick.

Your message mentions that your eyes are inward. So esophoria.

Jaa limits at admission for esophoria:

10 prism diopters measured at 6 m.
6 prism diopters at 33 cm.


For FAA Class 1 and Transport Canada :

6 prism diopters.

If you exceed FAA and TC asks for a specialist advise. No hope is lost.

One interesting thing in the US is that if you don't meet the standards on a particular point there is the SODA. Statement of Demonstrated Ability.
Flight check with an instructor to prove that you can fly safely. And your Class 1 at the end if it is good.

If you need more infos , no problem.

[Flight my fire]

I never was bothered with my vision while flying in a glider.

[Jimmy The Big Greek]

Well flight my fire, If you see double with or without any prism correction its a NO NO for both FAA or JAA. Maybe with a SODA you can get an FAA

DuffyDuck I think you chanses for a JAA medical are pretty good since you can the maddox rod and you have 100 arc of depth perception. But be prepared that in Germany they have a little bit of luftwaffe mentality and maybe your of doing a medical in another country.

Anyway, I dont think that the JAA will fail a person only based on stereoscopic vision but more likely due to the underlying conditions.

I beleive that if you have good Convergence, no diplopia and not to severe squint you should not have any problems.


Anyway good luck to you

[Flight my fire]

hi there.

Yes Jimmy of course it's a no no for both JAA and FAA.
I don't see double without my glasses. I don't see double with my prisms , they help the fusion. so no problem at all , i see single.
It would be a bit double if i had my correction for myopia without prisms. but with my prisms everything is normal. ( they are worn to compensate). No problem to appreciate distances while driving.

[Jimmy The Big Greek]

Well I think that you will have a problem. They will test your fusional reserves (how strong your fusion is). They put prism in from of your eyes and increase the prism strength to see how strong fusion you have. If you already have prisms in your glasses to prevent diplopia it means that your fusional reserves are not very strong. The JAA and FAA are very strict in diplopia. I really dont think they allow people to wear glasses with prisms. BUT I AM NOT A MEDICAL DOCTOR so don't take this for granted but I strongly beleive that you are going to run in to problems.


I think the best thing for you is to go to Gatwick and do your medical. I have told you this several times before. pprune is a fantastic tool for pilots where we can share information and help eachother but to get a definite answere you need to go and do the medical.

I just want to clarify some things regarding muscle imbalance.
Since I am Greek I undrestand medical terms easy.


There are two types of strabismus.

Latent Strabismus also known as heteroPHORIA. The eyes normaly fuse on the object except when tired, fatigued etc where the patient may encounter diplopia. The JAR-FCL have set out standards about this but even if the applicant does not meet the requirments for heterophoria. If he has strong enough fusion that prevents diplopia he will be ok.

Next form of strabismus is the Manifest Strabismus or also known as heteroTROPIA where the eyes constantly deviates. This form of strabismus gives diplopia unless there is a deep suppression hence no stereoscopic vision (depth perception).

[DuffyDuck]

Hey Jimmy. I checked this paper i got from the doctor. But i´m going to get a second opinion before i make an apointment with gatwick.
As i said, maddox positive; refraktion is 0 on both eyes; visus is 1.25 each eye; I have got a slight esotropie (not trophi). Ther are some numbers which i don´t realy understan, so i check with another doc. I believe the strabismus angle is about 3-7 degrees.

But: all other things are ablolutely fine. The doc said, i´ll never suffer double vision. I use both eyes and have small stereovision (100 arc seconds). i don´t wear any glasses.
the jar´s don´t tell anything about tropie, just trophi.

[Jimmy The Big Greek]

Well then you have a manifest strabismus (HETEROTROPIA). You say that you have ESOTROPIA. ESO in GREEK means inward so one of you eyes is pointing towards your nose. You also say that it is about 3-7 prism diopters. Thats probably 3 diopters at near distance and 7 diopters at far distance.

Since you have very good vision in both eyes (no amblyopia) then I can assume that you have alternating strabismus.

I think that you should be fine but ones again I think you might run in to problems with the German JAA because they don't follow the JAR-FCL 3 correctly.


Ps. Just out of curiosity, lets do an experiment. Take a A4 paper and put it between your eyes and look at a object. Close left eye and you should only see half of the object with right eye. close right eye then you should see the other side of the object. Now open both eyes. If you see the whole object then you have binoccular vision. If you only see one half of the object then you are suppressing. Depending which side you see you can determene which eye is dominant.

[DuffyDuck]

So, i did as you told me. You were right. It´s alternating.
But i don´t have 3 and 7 prismdiopters, i got between 3 and seven degrees (i believe 1degree is about 1,745 prisms).
Concerning the papertest: i see both sides. I ´ve tried it with my hands as well. Also following my fingertips did never cause double vision.
My next step will be to contact a specialist and then call gatwick. they should be able to presume my chances.
I really hope so much that it works as it has always been my dream and still is. I won´t try in germany as i know they even translated the paragraph in a wrong way (here it says: people with bad stereopsis don´t get a medical. thats it.

[Flight my fire]

Hi there.

Thank you Jimmy for your explanations.
Yes I know that I may have problems. But that's the reason why i'm still looking for inforrmations on the forum before doing anything in regards of a medical appointment.

But i'm sorry to insist it is mentioned nowhere in the texts. I don't discuss the fact that diplopia is a factor of unfitness but i read nowhere if it includes with prisms.
I agree with you in regards of my fusional reserve, in my case it is not huge. I
I see normally with prisms , and my strabismus ( microstrabismus) is unvisible just detected by tests.People don't know i have it if i don't say it. I have no problem when wearing my glasses I see SINGLE, and i have no problem in practical life, as well for driving for the appreciation of distances on the road with other vehicles, by day and by night. And i never had any further complications since the time i began wearing prisms ( 3 years ago ). It is stable. and when i'm tired I don't have diplopia appearing in my vision.
An instructor would like to test me, i wouldn't have any problem looking outside, watching my instruments and reading a chart in the same time.
I have 6 diopters prisms.
I still have a partial depth perception because i can see a few stereopsis. Not 100 %.
Last year i had a test for parallelism ( as said by doctor ), the spectacles with a red glass. A red bar horizontal or vertical ( for hyperphoria ), appear and the doctor switches on a little white light and you have to give the position of the bar. If it crosses the white light or if it is aside the light.
I succeded the test.

I'm going to go to an orthoptist's for a new check-up in a few days before discussing my case with aviation doctors.
I'm down to earth and I want to get as much infos as possible before calling medical division.

Duffy. Good for your check-up. I didn't understand everything with your measure units.
Did your specialist convert in prism diopters ? Your problem seems not to be important so maybe you may have chances.
Send a letter to Gatwick explaining your case, they are helpful, they will evaluate your chances and therefore you will know if it is worth trying.

Summer is the great season for cumulus !!! Hope you fly nice circuits with your glider !!!

[Jimmy The Big Greek]

You need to specify more about your medical condition. If you have amblyopia then its strange that you got an FAA 1 class medical without a SODA since they require 20/20 in each eye.

If you have at least 6/9 of vision in your amblyopic eye then it should not be a problem for a jaa medical.


Anyway good luck

[Farrell]

I have an FAA Class 1 with no SODA.

I have amblyopia in my right eye which is a lot more than 6/9.
My physician in Paris told me that because I had it from a very young age that I have learned to compensate for it at this stage.

I threw up the depth perception question to her and she said that most people lose all depth perception after about 20ft anyway.

So, I have my FAA Class 1. Now, all I have to do is go and do my training in the US and get about 1000 hours of ME time and see if I can convert to JAA or EASA at some point in the future.

[redsnail]

I am cross eyed. No idea what sort, my left eye turns in a smidge. No test required in Australia for double vision (Held an Aus Class 1 medical) and I was tested for my initial JAA Class 1 in Gatwick for stereo vision.

I was told by the doc any hint of double vision = fail. However, I only saw 1 image of whatever it was I was looking at = pass. I do need to wear specs because I also have astigmatism and my right eye sees things a bit blurry.

I do not have a problem flying at all. Hold a Class 1 medical and got ~5800 hours.

Top tip. Do the medical and let them tell you what's wrong. If anything.

[erman152]

Hey guys, I recently moved from australia to turkey, where I held a class 1 medical in aus.
I went for a class 1 JAR medical in turkey and they failed me for having zero depth perception. I am now considering going to Gatwick and getting my class 1 medical there. Does anyone know if they test for depth perception at Gatwick or if they do can you still pass with zero depth perception but perfect vision?
I have perfect vision just zero depth perception, as I find this ridiculous, I was tested for about 8-9hours for a full medical where I had friends finish there medical in 3 hours.

If I could get some information on this it would be great :)

[David Horn]

Stereopsis and depth perception are completely different things.

Stereopsis serves as an aid to depth perception, but you can have perfectly normal vision without it. The brain has a multitude of ways to figure out depth; stereopsis is just one of them.

It's not tested for in the UK Class 1 medical (in fact, there used to be a statement in the manual saying stereopsis was specifically not required) and it's of very limited use in flying anyway.

[arimator]

Yesterday I had my initial JAA category 1 medical examination in Finland and I didn't pass because I have eso 16 (far) and eso 12 (closer). I never had any problems with stereo vision and never seen a double vision. I already contacted Gatwick via email. I'm shocked to find out this now because I have a Transport Canada category 1 medical and I have CPL with more than 200 hours. I hope that I didn't spend all my money for nothing. It's really frustrating.

[erman152]

Thanks for your reply Davıd... So now when I go to U.K would I be tested for depth perceptıon ın any other way...and if I do get tested, ıs there a possibity of me failing wıth no depth perceptıon?

[David Horn]

I assume that if you can get into the building without tripping over the pavement outside it's an adequate test of depth perception. There are specific tests for stereopsis available; as far as I know they're not used in the Class 1.

As I said, everyone has depth perception, but not everyone has stereopsis. Many ways to skin a cat etc, and the number of monocular people who lead perfectly normal lives should be testament to this!

[erman152]

I belıeve so too.. I have no problem wıth depth perceptıon at all wıth catchıng or anythıng lıke that just when ıt comes to those tests I cant do ıt.. I just hope my medıcal ıs not faıled upon depth perceptıon as my vısıon and everythıng else ıs perfect.