was "slap off" written on a prescription?
what prescription was it?
what was the prescription for?
Another expert actually gave me the answer to this one as I did not originally know because I am not a doctor that prescribes eye glasses.
It is "Slab off" on the prescription and it is a technique that is used on the lens when making bifocals.
"It's actually "Slab Off", not slap off. "Slab Off" refers to a lens grinding technique used to neutralize an unwanted prismatic effect when looking through a bifocal correction. The unwanted prismatic effect is caused by anisometropic lens corrections. Anisometropia is a condition in which there is a significant difference in the refractive errors between the two eyes."
I hope this is helpful, and I would like to thank the other Expert for providing this answer.