44. Inflammation of the cornea due to viral infections*
Covers viral corneal inflammation, naming herpes simplex, varicella zoster and adenovirus as the main causes, with measles and rubella less common. It takes herpes simplex dendritic keratitis first, with its tree-like epithelial pattern, relapse mechanism, symptoms, complications and acyclovir treatment, then disciform herpetic keratitis, adenoviral epidemic keratoconjunctivitis, and herpes zoster ophthalmicus, which is linked to the trigeminal ganglion and its complications. A picture accompanies the dendritic keratitis section.
Topic 44 of 91 in the MU Sofia syllabus for Ophthalmology (Medicine, Year 4). The free AceMed note covers it in 1 section, about 302 words (2 min of reading), with 15 flashcards.
superficial infection of the cornea → tree-like arrangement of fluorescent-positive epithelial cells above the infected nerve endings
etiology: infection of ganglion Gasseri
relapse after primary asymptomatic conjunctivitis or blepharitis → after healing of primary defect virus remains within the ganglion → weakening of immune system leads to relapse
symptoms: foreign body sensation, pain, photophobia, lacrimation, lid swelling
diagnosis: typical tree-like efflorescence, edema of the corneal epithelium, ciliary injection, decreased corneal sensibility
complications:
relapse with infiltration of the Bowman membrane & anterior corneal stroma → scarring
metaherpetic ulcer by detachment of collagenases from ulcer margins
treatment: virostatic eye drops (Acyclovir), abrasion only in recurrences
prognosis: recurrent
Keratitis discomformis: Herpes simplex virus
deep, parenchymatous viral infection → plaque-shaped central stromal clouding
complications: secondary glaucoma due to inflammatory changes in chamber angle, relapse
treatment: local corticosteroids
prognosis: recurrent → scarring
keratoconjunctivitis epidemica: adenovirus
symptoms: corneal inflammation → conjunctival irritation & swelling of the plica semilunaris & of regional lymph nodes, subepithelial infiltrations composed of leukocytes & lymphocytes → leading to scarring & decrease in visual acuity
treatment: steroid-containing eye drops → no complete resolution of the scars
Zoster opthalmicus/ Zoster keratitis: endogenous relapse of chickenpox within innervation area of the first trigeminus branch by the Varicella zoster virus persisting within the ganglion Gasseri
etiology: elderly, immunocompromised adults
symptoms: pain, deep corneal infiltrates persisting over months
complications: involvement of N. nasociliares → conductivities, scleritis, uveitis, secondary glaucoma, bleeding into anterior chamber, ocular muscle paresis, ocular nerve inflammation & retinal necrosis
