Snapshot A 55-year-old woman was referred to an ophthalmologist for eye pain and photophobia. She says her symptoms are associated with visual blurriness and has noticed some "redness" in her sclera. She has a past medical history of hypertension that is adequately managed with diet and exercise and rheumatoid arthritis. She endorses previously having an oral vesicular lesion that self resolved without treatment. Physical examination is notable for ciliary flush of the left eye along with decreased corneal sensation. Slit-lamp examination with a fluorescein stain demonstrates dendritic lesions concerning for herpes simplex virus keratitis. Introduction Overview an ocular manifestation of herpes simplex virus (HSV) Epidemiology Incidence most commonly HSV-1 ETIOLOGY Pathophysiology ocular exposure to viral-laden lesions HSV-1 enters sensory nerve endings and lays dormant in the trigeminal nerve ganglion when reactivated, it travels down the axon and causes lytic damage to ocular tissue HSV-1 also leads to inflamation of the retinal arterioles, causing vaso-occlusion and subsequent rapid necrosis of the retinal tissue Associated conditions HSV-1 infection Presentation Keratitis symptoms ocular pain visual blurring discharge photophobia physical exam chemosis reduced sensation of the cornea ciliary flush corneal dendritic lesions on slit-lamp examination with fluorescein Conjunctivitis and blepharitis physical exam eyelid inflammation conjunctival inflammation vesicles on the lid margin Studies Slit-lamp corneal dendritic lesions on slit-lamp examination with fluorescein Differential Contact-lens associated infectious keratitis differentiating factors a possible complication of contact lens use common organisms Pseudomonas aeruginosa (most common) Staphylococcus Streptococcus Serratia Acanthamoeba Herpes zoster ophthalmicus differentiating factors typically prodromal features of fever, malaise, and headache are present acute and painful vesicular lesions are present via a single dermatome of the trigeminal nerve Treatment Medical topical or oral antiviral medications indication first-line treatment comments topical and oral antiviral medications against HSV are equally effective never give steroids medications topical trifluorothymidine topical or oral acyclovir Surgical corneal transplant indication in severe corneal scarring from keratitis Complications Corneal blindness Acute retinal necrosis Chorioretinitis Prognosis Can lead to corneal blindness