Corneal topography

[Dr Jekyll]

I know that if you apply for a class 1 medical and your astigmatism exceeds 2 dioptres you have to go for a corneal topography examination. What exactly are they looking for on this and is there any way to judge in advance what your chances of passing may be?

[nonsense]

Presumably they are looking for kerataconus, where the surface of the cornea is uneven or bulged.
Curiously I have about 3 dioptres of cyl (astigmatism) in one eye (due to cataract surgery 28 years ago), and kerataconus, -4 dioptres of myopia, but almost no cyl at all in my other eye.

[Blues&twos]

Keratoconus is a progressive condition, so presumably the topography requirement is to ensure it isn't kc or anything else which may slowly worsen vision. The vision can reduce slowly enough that the patient won't necessarily notice straight away.

[nonsense]

Originally Posted by Blues&twos

Keratoconus is a progressive condition, so presumably the topography requirement is to ensure it isn't kc or anything else which may slowly worsen vision. The vision can reduce slowly enough that the patient won't necessarily notice straight away.

Mine doesn't seem to have progressed in 30 years; I'm seeing my optom this week, I'll ask...

[Blues&twos]

Originally Posted by nonsense

Mine doesn't seem to have progressed in 30 years; I'm seeing my optom this week, I'll ask...

Hi, mine progressed quite quickly after diagnosis as a child, requiribg surgery.
it seems the condition varies quite a lot between individuals:

The course of the disorder can be quite variable, with some patients remaining stable for years or indefinitely, while others progress rapidly or experience occasional exacerbations over a long and otherwise steady course. Most commonly, keratoconus progresses for a period of 10 to 20 years before the course of the disease generally ceases in the third and fourth decades of life.

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[Dr Jekyll]

That's interesting, thanks. So if they have no Keratocunus it should be OK.

[Blues&twos]

I don't know what else they may be looking for, Dr. Jekyll. Keratoconus is just a corneal condition with which I'm familiar - unfortunately.
Good luck with the medical!

[TomahawkEI]

I think you can tell a lot more than Keratoconus. Can’t you tell the amount of astigmatism and refraction using this too, compared to an autofractor?