The red eye. Infectious conjunctivitis, keratitis, endophthalmitis, and periocular cellulitis.

Patients presenting with a red eye may have a minor, self-limited inflammation of the ocular surface or a vision-threatening infection such as endophthalmitis or orbital cellulitis. Careful evaluation of distinctive clinical signs is necessary to determine the level of ocular involvement. A knowledge of the common microorganisms causing various eye infections (Table 6) can provide the basis to guide appropriate laboratory investigation and initial therapy. Detailed reference textbooks on ocular infection should be available, and ophthalmologic consultation should be considered in these cases to assist in diagnostic investigations and to monitor potential ocular complications.