Although hailed as a means of delaying the onset of glaucoma, latanoprost (Xalatan) has been shown to cause changes to pigmented tissue. Its continual use may gradually change the colour of your iris by increasing the amount of brown pigment. It also turns your eyelid a darker colour. This can be particularly distressing if you only use the drops in one eye, especially as any colour change may be permanent.
Latanoprost has also begun to rival Rogaine as an unauthorised treatment for baldness after it was found that the drug increases the length and thickness of the eyelashes. Other side-effects include macular oedema, or swelling of the macula, and greater sensitivity to light as well as redness, swelling and discomfort of the eyes.
The most common side-effects of brimonidine tartrate are burning, stinging, blurring, itching and an allergic response. Occasionally, the drug will also cause corneal erosion and staining, and fatigue or drowsiness. Problems may also be caused by the preservative used in brimonidine tartrate as it can be absorbed by soft contact lenses.