Pain in one eye is a broad term Is the pain aggrevated in the evenings? Is it associated with redness? Since when is it there? Is your vision deteriorated else normal? I did not understand what do you mean by small circle? Is it redness in the form of circle? Is it a circled elevation? Is it to the nasal side of your cornea? Kindly look for "follow up" on the screen so we could discuss accordingly; Sorry for putting up so many questions but it helps diagnosing the right disease/disorder. Hope it helps by following up :)