It’s important to know that cystine-depleting oral medicines (medicines taken by mouth) do not reduce the build-up of cystine crystals in your cornea. These medicines are delivered to organs in your body through your bloodstream. But these medicines cannot reach your cornea since it does not have blood vessels. CYSTADROPS is an eye drop medicine that reduces the build-up of cystine crystals in your cornea over time with continuous treatment.