Muggles' Guide to Harry Potter/Magic/Conjunctivitus

Overview
The Conjunctivitus curse apparently causes temporary blindness.

Extended Description
In Harry Potter and the Goblet of Fire, Harry is required to get past a Dragon in the First Task of the Triwizard Tournament. Dragonhide is nearly impervious to most spells – it takes several wizards working in concert to Stun a dragon, for instance – so in order to disable a dragon single-handed, you must attack its only vulnerable area - its eyes. The Conjunctivitus curse is the one you use to do that.

We are told about this spell, but we do not see it actually executed, so we do not know the incantation.