Table 3.

Clinical characteristics of the different forms of microbial keratitis

Clinical characteristics	Bacterial keratitis	Fungal keratitis	Acanthamoeba keratitis
Onset of symptoms	Rapid	Several days62	Rapid
History	Contact lens wear, trauma, and ocular surface disease	Vegetative trauma, contact lens wear, and ocular surface disease	Water exposure and contact lens wear; may have been treated prior as herpes simplex
Key differentiating slit lamp findingsa	Round or oval shaped lesion, and anterior chamber flare81	Feathery borders, satellite lesion, and necrotic slough81 *Yeast infection mirrors bacterial ulcers62	Early:85 epithelial disruption without stromal disease and perineural infiltrates Late:85,86,103 ring infiltrate
Treatments	Fluoroquinolones, chloro-fluoroquinolones, and fortified antibiotics	Natamycin, voriconazole, and amphotericin	Polyhexamethylene biguanide, chlorhexidine, propamidine, neomycin, and oral voriconazole
Healing time (days)	3.5–6.898,b	31–40102	140–547103,127,129 Steroid:103 163±50c No steroid:103 94±45c
Percentage with visual acuity worse than 20/30	13.99	30129	0 (early diagnosis)85 44.4 (late diagnosis)85 Prior steroid use equaled worse outcome86,103
Percentage requiring penetrating keratoplasty	09–13131	16.8124	20–3287
Cost7 (US$)	1,200–1,800	4,648	5,697

Notes:

^aAll conditions will likely have redness, photophobia, discharge, and significant pain.

^bFor ulcers ranging from >1 mm² to <4 mm².

^cData presented as mean ± standard deviation.