Ophthalmology - infections
Description
- Ophthalmology - ocular and periocular infections: conjunctivitis (bacterial, viral, chlamydial, gonococcal, neonatal), microbial keratitis, orbital/periorbital cellulitis, endophthalmitis, dacryocystitis, herpes zoster ophthalmicus
Epidemiology
- Bacterial/viral conjunctivitis extremely common, highly contagious (viral); neonatal conjunctivitis linked to maternal STI status
- Microbial keratitis strongly associated with contact lens use
- Orbital cellulitis more common in children, usually from sinus spread
Aetiopathogenesis
- Conjunctivitis: adenovirus (commonest viral), Staph/Strep/Haemophilus (bacterial), Chlamydia trachomatis (chronic, follicular), Neisseria gonorrhoeae (hyperacute, sight-threatening, esp. neonatal)
- Microbial keratitis: Pseudomonas (contact lens-associated, rapidly destructive), Staph/Strep, Acanthamoeba (contact lens + water exposure), HSV (dendritic ulcer)
- Orbital cellulitis: extension from ethmoid sinusitis typically, Strep/Staph/Haemophilus - postseptal (orbital) vs preseptal (periorbital) distinction is critical (postseptal threatens vision/CNS)
- Endophthalmitis: post-surgical (cataract surgery) or post-traumatic, or endogenous (bacteraemia/fungaemia) - sight-threatening emergency
- Herpes zoster ophthalmicus: VZV reactivation in V1 dermatome, Hutchinson's sign (nasal tip vesicles) predicts ocular involvement
Diagnosis
- Clinical exam +/- slit lamp; swab for gonococcal/chlamydial conjunctivitis (esp. neonatal, hyperacute purulent discharge) - urgent as gonococcal keratitis can perforate within hours
- Preseptal vs orbital cellulitis: proptosis, ophthalmoplegia, pain on eye movement, reduced acuity, chemosis = postseptal (orbital) - needs CT orbits +/- sinuses
- Corneal scrape and culture for suspected microbial keratitis before starting antibiotics
- Vitreous tap for suspected endophthalmitis
Management
- Bacterial conjunctivitis: topical antibiotic (chloramphenicol); gonococcal: same-day ophthalmology + IM/IV ceftriaxone + treat for concurrent chlamydia - sight-threatening if untreated
- Neonatal conjunctivitis: urgent assessment - gonococcal and chlamydial causes need systemic (not just topical) treatment and maternal/partner screening
- Microbial keratitis: urgent ophthalmology, intensive fortified topical antibiotics, stop contact lens use
- Orbital cellulitis: IV antibiotics, urgent ophthalmology/ENT, surgical drainage if abscess or vision-threatening/no improvement - postseptal disease is an emergency; preseptal can often be managed with oral/IV antibiotics without imaging if mild and improving
- Endophthalmitis: emergency intravitreal antibiotics +/- vitrectomy
- Herpes zoster ophthalmicus: oral antiviral (valaciclovir/famciclovir) within 72h, ophthalmology review for corneal/uveal involvement
Associations
- Contact lens misuse (overnight wear, poor hygiene, swimming) with keratitis
- Sinusitis with orbital cellulitis; STI status with gonococcal/chlamydial conjunctivitis (screen for other STIs, notify partners)
- Immunosuppression with endogenous endophthalmitis
Natural history & complications
- Viral/bacterial conjunctivitis - self-limiting over days to two weeks
- Untreated gonococcal keratoconjunctivitis can perforate within 24-48h - true emergency
- Orbital cellulitis can progress to cavernous sinus thrombosis or intracranial spread if not treated promptly
- Endophthalmitis carries a high risk of permanent vision loss even with prompt treatment
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