Have had several trip to the specialist to get fitted for hard lenses for my Keratoconus .. actually I have PMD ( Pellucid Marginal Disease) which is often lumped into same category as treatment is virtually the same.
The eye disease is moderate in my left eye on very mild in right.
After several exams and complaining that when I wore both contacts my vision seems almost worst than just one in my left eye was discovers I have naturally occurring monovison. Actually- I am pretty sure I told last couple eye doctors that my prescription is usually a + on one side and negative on the other but no attention was paid to me …
So what this means is I am far sighted in my right eye and near sighted in my left. When I wear glasses the PMD is not corrected and cant see very well. When I wear hard contact on my left eye I have perfect vision on that eye and it takes care of every up close.
So… in a nit shell I can wear one contact on nothing on my right eye. The left eye looks after things close up and right sees things far way.
Contact lens wearers will often create this affect if they need to wear bi-focals and wear two lenses one correcting near sightedness and the other far sightedness.
This is good news for me as less expense replacing only one contact not too mention cleaners, etc and good for my PMD to have nothing on the cornea.