CIALIS may uncommonly cause vision changes, such as seeing a blue tinge to objects or having difficulty telling the difference between the colors blue and green.
In rare instances, men taking PDE5 inhibitors (oral erectile dysfunction medicines, including CIALIS) reported a sudden decrease or loss of vision in one or both eyes. It is not possible to determine whether these events are related directly to these medicines, to other factors such as high blood pressure or diabetes, or to a combination of these. If you experience sudden decrease or loss of vision, stop taking PDE5 inhibitors, including CIALIS, and call a doctor right away.
taken from:
Lilly.com | Eli Lilly and Company