If a person has fatal insomnia is both of their pupils small or is it only one eye?

Extremely rare. This is an extremely rare prion disease and diagnosis is based upon pathologic testing and physical exam findings may vary. The only reference to pinpoint pupils i could find stated that both were pinpoint, not just one. Here's a good article: http://www.Ncbi.Nlm.Nih.Gov/pmc/articles/pmid/17406189/ and http://www.Ncbi.Nlm.Nih.Gov/pmc/articles/pmc3214133/.