Chapter 30: Red Eye Assessment & Diagnosis

Key diagnostic distinctions are drawn based on the nature of discharge—separating the purulent exudate of bacterial infections from the watery presentation of viral or allergic etiologies—and the location of redness, such as the ciliary flush associated with serious uveal or corneal disease versus the diffuse injection of conjunctivitis. The chapter outlines a systematic physical examination, including visual acuity testing, fluorescein staining to detect corneal abrasions or dendritic lesions indicative of herpes simplex keratitis, and eyelid eversion to inspect for foreign bodies. Significant attention is given to the differential diagnosis of eyelid disorders like blepharitis, hordeolum, and chalazion, alongside conjunctival conditions including hyperacute gonococcal infections and seasonal allergic reactions. Crucially, the text differentiates these common ailments from urgent pathologies such as orbital cellulitis, characterized by painful eye movement and proptosis; acute closed-angle glaucoma, which presents with halos, severe pain, and fixed pupils; and anterior chamber abnormalities like hyphema or hypopyon. The discussion concludes with management implications, noting that while many cases of acute conjunctivitis are self-limiting, conditions involving the cornea, uveal tract, or significant intraocular pressure elevations require immediate ophthalmologic referral.