Ballad of the Lens Calculator

Axial length, twenty-three point four one.
Or twenty-three point four four. Let's take it again.

I sit in a dark little room by the copier
With a machine that measures eyes
It shoots a light to the back of the retina
And mostly it tells no lies
But the cataract's white as a wedding cake
And the light won't make it through
So I pull out the immersion A-scan, darlin'
Like my mentor used to do

Next one wore hard lenses for forty years
Rigid gas permeable, round and proud
"Stay out of them three weeks," I told her twice
She came in wearing them. She said it out loud
Then a man with silicone oil in his eye
Sound slows down in the oil, you see
So the A-scan swears his eye is a mile long
And I B-scan till half past three

Oh, the Ks don't match, and the topography
Is fighting with the Pentacam
I've run Barrett, Haigis, Hoffer Q
And Kane, and I don't know who I am
Holladay, SRK/T, EVO and Hill
They all say a different thing
Just give me one honest cornea, Lord
And a quiet afternoon in spring

Then a fella says, "I had LASIK in ninety-nine"
And a lady had RK, sixteen cuts
Her cornea's flatter every afternoon
So I run Barrett True-K and I pray, and such

I wrote twenty-one point five on the sheet in blue
Somebody typed twelve point five
Now it's five o'clock and the OR calls
With a speculum in, and the patient alive

Oh, the Ks don't match, and the topography
Is fighting with the Pentacam
Just give me one honest cornea, Lord
And a quiet afternoon in spring

"Can you recalculate? He's on the table."
Yes, ma'am. Twenty-one point five.
It was always twenty-one point five.