infectious bacterial keratitis (corneal ulcer) Flashcards
infectious bacterial keratitis (corneal ulcer)
assess low, borderline, high risk of vision loss
chlorofluoroquinolone (Besivance) / 4th generation fluoroquinolones off-label older fluoroquinolones on-label
cycloplegia for secondary uveitis, no steroids
using steroids to speed healing / timing and cautions
tapering medications / signs of improvement
outpatient care / hospital inpatient care Tx decisions and issues
culture and sensitivity, repeat if needed
fortified antibiotic drops (need compounding pharmacy)
symptoms
R S Sensitive to light with Red eye (intensely) V Vision change (reduced, disrupted) and P Pain (acute unilateral, can include profuse tearing)
signs
focal stromal infiltration surrounding excavation (ulcer) AC cells and flare (hypopyon?) conjunctival injection (even deeper to episcleral?) purulent discharge? mucoid plugs? eyelid edema? folds in Descemet’s membrane?
pathophysiology
• once corneal defenses are breached – direct corneal trauma, chronic eyelid disease, tear film abnormalities affecting the ocular surface, hypoxic trauma from contact lens wear, etc. – the cornea is prone to infection
• pathogenic bacteria colonize the corneal stroma and immediately become antigenic by releasing enzymes and toxins
→ antigen-antibody immune reaction
→ inflammatory reaction
• the body releases PMNs (PolyMorphoNuclear leukocytes) which
aggregate at the area of infection, creating an infiltrate
• the PMNs phagocytize and digest the bacteria
• the collagen stroma is poorly tolerant of the combined bacterial and
leukocytic enzymes and undergoes degradation, necrosis, and thinning → scarring of cornea
→ cornea may perforate
→ possibility for endophthalmitis
• the most common infective organism in bacterial keratitis is
Staphylococcus aureus; in cases involving contact lens wear and cosmetics, the most common infective organism can be Pseudomonas aeruginosa
mild diameter and stromal depth
< 1-2 mm and < 20%
mild setting and course
outpatient, 5-10 days
moderate diameter and stromal depth
2-4 mm and 20-50%
moderate setting and course
outpatient, 10-20 days
severe diameter and stromal depth
> 4 mm and > 50%
severe setting and course
hospital and 3 weeks
Low AC reaction
none to minimal
Low RSVP
c/w signs
Low discharge
none to minimal
borderline AC reaction
mild
borderline RSVP
c/w signs
