The standard eye test

[GarethB]

When I was 17, the RAF had machines where shapes randomly moved and you had to click when you could see them in the field of vision plus you had to do some other simple addition and letter recognition too.

Impossible to guess, yet I passed with flying colours. 2 weeks later in the medical once the swelling round my eyes had gone down after a praticularly violent game of rugby the doctor could not beleive I managed to pass the visiual tasks the preveous couple of weeks whith 2 black eyes and extremely bad eye sight. Had to get my parents to collect me and my car as the doctor said my sight was so bad and it would be negligent of him to let me go and drive!

[Matthew_]

Drive a jet but not a car! So what happened? Was it just a bad eye / good eye day scenario?

[GarethB]

At that time I was only applying so did not even come close to being able to crash a simulator

This was before KC was officially diagnosed so certainly not a case of bad eye day due to lenses. Up until that point never even had to wear glasses.

The prevous month I had just passed my driving test. Never read a number plate

The examiner said "read the registration of the blue car over there."

I replied " Which one, the Cavalier 2.0 GL or the Fiesta 1.0 Popular?"

Suppose he must of thought if I could identify the cars to that level of detail my sight must have been more than good eough to read a registration!

[Matthew_]

Yeah,
That's an important point you are making. Because we adapt to the situation, that effectively makes the condition more invisible. I think that's why it is sometimes a challenge to get understanding. I can well imagine someone saying 'there's nothing wrong with your eyesight, you can tell what that car is straight away!'
I am not suggesting that we make KC more obvious to those around us, its just an observation.

[Barney]

Disappointing that despite it's reputation, eye-tests at Moorfields don't seem to be as sophisticated as others have found at other hospitals. Presumably they don't feel the need but seems a strange approach. Must be harder to offer a solution if you don't fully understand the problem.

Sometimes occurs to me as I sit in that chair covering one eye that the person doing the testing probably has little idea of what I see.

[Matthew_]

I can relate to that! On the other hand I have found the optometrists very understanding. But other eye professionals have tended just to define the KC by the surface distortion ie a measurable parameter. I think this is just human nature. Some people, right-handed brains maybe, can only relate to something which can be physically measured. Others are more empathic.

Does anybody know how possible it would be to develop a KC specific eyesight test?

[Andrew MacLean]

Matthew

I am pretty sure that such a test could be devised, but I am not sure that it would be desirable. would it test sight with or without lenses?

I think that in theory at least the "with lens" sight of most contact lens wearing keratoconics (I blush to think that I used that word) ought to be equivalent to the ordinary sight of a normal eye.

The differences in the sight of advanced kerato-thingies and those with less developed cones would be far greater than the difference between non-keratoconics and those with mild KC.

So the skilful optometrist will apply her or his art and deftly vary the standard test and other testing tools available to obtain the best reading for each individual patient (do we have to call ourselves clients now?)

Andrew

[Anne Klepacz]

There are more sophisticated eye tests for KC. A few years ago I and a number of other KC Group members took part in some research which was looking at developing soft contact lenses for KC. That involved a whole battery of tests. I've forgotten most of them, but do remember that there were eye charts which went from black to various shades of grey (down to near invisibility) and also involved trying to read them in different light levels. Those certainly highlighted the difficulties we have! As to why tests like this aren't standard in the hospital service - I guess it probably comes down to lack of time. We KC-ers already take up a lot of clinic time with our odd shaped eyes without adding in lots more tests. Perhaps one of the clinicians here could comment?
Anne

[Barney]

I'd assume because it's not thought that more measurement would reveal any more. But then there's the case for more measurement in the immortal wisdom of Donald Rumsfeld:
"As we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know."

I'm just back from the dentist after one of my teeth came off second best to a piece of crackling. With the occasional chipped tooth and a yearly checkup I spend more time there than in the KC clinic.

[Matthew_]

Maybe its because contact lenses can in many cases resolve the problem. Ie 'why spend time measuring how much KC you have, when these lenses might make it all go away? Try these lenses, if they do not work, come back and we'll try something else'. Basically, measuring KC is not going to suggest possible remedies: It's not like if you have ghosting you need this kind of lens or if you cannot see 3D you need another. That's mostly trial and error, fit and tolerance. Perhaps there is no point in being able to measure or even understand your symptoms. My recent experience is that I have very little distortion in my corneas and yet I do have significant symptoms: ghosting, blurring, photophobia etc. The optometrists seemed to deal with the symtoms, she was interested in what my eyesight was like. The opthomologist was not. He was only interested in the measurable (the distortion) which was mild, so I went into the 'not very interesting' pile. At first, I was frustrated with this, I thought, 'surely if I tell him how bad my eyesight is he will look for a solution.' But now I can see why this approach is used. When I tried the rgp's : I was amazed at the improvement in eyesight. I am lucky, the lenses work and initial indications are that I will be lens tolerant. When I went back to (a different) opthomolgist he stated that response to the lenses was the best indication of KC you could have and all this measuring of corneas was guess-work at best. No wonder then the lack of enthusiasm about all these different tests. With the lens in, the optemtrist said she could see the KC in my left eye as plain as day, the cornea was sort of slumped against the lens. Why am I boring you with this?
I think it shows that KC is very complex. Perhaps you could measure it more meaningfully, but will this help? It probably comes down to trial and error at the end of the day. That's OK if you are lucky like me and have mild and responsive KC but others have to have a whole lot of trialling done on them, which must be grim. But at least we can understand why.