May be a little misunderstanding here.
CONJUNCTIVITIS is usually a very brief and transient condition, where the outer (transparent) layer of the eye gets inflamed through infection. If it's viral (the large majority) it generally requires no treatment, and gets better spontaneously in a matter of a few days. Bacterial conjunctivitis might take a bit longer to clear, and might require treatment with antibiotic drops.
But conjunctivitis does not usually affect visual acuity; certainly has nothing whatsoever to do with astigmatism; and would not normally get in the way of passing a routine flight crew medical.
Do not be afraid of renewal. Discuss your situation with your AME. That's our job ! !