**3.1 Prostaglandin analogs**

Are the most powerful and efficient agents for controlling intraocular pressure among all current ocular hypotensive medications [12]. Latanoprost has been shown to induce squamous metaplasia, to stimulate HLA-DR overexpression at the conjunctival surface, and to cause significant changes in the metalloproteinase and tissue inhibitor balance [10, 13].

Conjunctival hyperemia is the earliest and most notorious side effect. The hyperemia is due to vasodilatation and not from an allergic reaction, as seen with other drug classes. This manifestation is more marked during the first month of use.
