Bacterial keratitis

Non-herpetic viral keratitis, overwhelmingly adenoviral, produces copious watery discharge, severe irritation, and preauricular lymphadenopathy that starts unilateral and spreads to the second eye. Management is supportive and infection-control focused; chronic subepithelial infiltrates are the vision-affecting sequela that sometimes needs ophthalmology-directed topical corticosteroid.

Herpes simplex keratitis is reactivation of latent HSV along the trigeminal nerve causing a corneal dendritic ulcer with pain, photophobia, and decreased corneal sensation. Diagnosis is clinical on slit lamp with fluorescein staining; treatment is a topical or oral antiviral, and topical corticosteroids are contraindicated in active epithelial disease.

Acanthamoeba keratitis is a corneal infection by a free-living amoeba, strongly linked to soft contact lens wear combined with freshwater exposure, diagnosed by microscopic examination of corneal scrapings and treated with prolonged topical antiamoebic/antifungal therapy that often fails to prevent progressive corneal destruction. Any contact lens wearer with a painful, non-healing keratitis that is not responding to antibacterial therapy needs this diagnosis considered and an urgent corneal scraping sent.

Microbial keratitis (infectious corneal ulcer) is the unifying vision-threatening syndrome of a painful red eye with a corneal infiltrate, produced by bacterial, viral, fungal, or amebic invasion of a breached corneal epithelium, managed by the same urgent pathway regardless of organism: emergent scraping for smear and culture before any drug is given, then broad empiric coverage narrowed once results return. Delay, misdiagnosis as simple conjunctivitis, or premature corticosteroid use converts a treatable ulcer into stromal melt, perforation, and permanent vision loss.

A corneal abrasion is a traumatic or foreign-body-related defect of the corneal epithelium diagnosed by fluorescein uptake under cobalt-blue light. Uncomplicated cases heal in days with lubrication and pain control, but contact-lens wear mandates antipseudomonal coverage and any red flag (rust ring, infiltrate, Seidel sign, hypopyon) demands same-day ophthalmology referral.

Conjunctivitis is inflammation of the conjunctiva from viral, bacterial, or allergic causes presenting with red eye, discharge, and preserved vision, diagnosed clinically by discharge character and managed with supportive care, targeted topical antibiotics, or topical antihistamine/mast-cell-stabilizer therapy.

Endophthalmitis is a vision-threatening suppurative infection of the aqueous and vitreous humors, most often exogenous after cataract or other intraocular surgery and less often endogenous from hematogenous seeding during bacteremia or candidemia. Diagnosis is clinical, confirmed by vitreous/aqueous tap, and treatment is emergent intravitreal antibiotics or antifungals with vitrectomy for severe cases.

Uveitis is inflammation of the uveal tract, classified by anatomic location as anterior, intermediate, posterior, or panuveitis and by systemic association such as HLA-B27 spondyloarthritis, sarcoidosis, or Behcet disease. Anterior uveitis presents with a painful red eye and photophobia diagnosed at the slit lamp, while posterior uveitis presents with painless floaters or vision loss, and treatment is topical corticosteroid for anterior disease escalating to systemic corticosteroid and steroid-sparing immunosuppression for recurrent, severe, or posterior-segment disease.

Acute angle-closure glaucoma is a pupillary-block emergency in which sudden closure of the iridocorneal angle blocks aqueous outflow, causing severe eye pain, halos, and rapidly rising intraocular pressure that can blind the eye within hours if not treated. Diagnosis is clinical plus tonometry and gonioscopy; treatment is immediate topical and systemic IOP-lowering therapy followed by laser peripheral iridotomy.