Tests
1st tests to order
corneal scraping: microscope slide
Test
Ideally, corneal scraping should be performed prior to starting antimicrobial therapy.
Gram and Giemsa stains are performed routinely, the others only if prompted by clinical suspicion.[32]
Result
Gram stain: bacteria, fungi; Giemsa stain: bacteria, fungi, Acanthamoeba species; Gomori methenamine silver stain: fungi; acid-fast stain: mycobacteria, Nocardia species; calcofluor white stain (fluorescent microscope): Acanthamoeba species
corneal scraping: cultures and sensitivity
Test
Ideally, corneal scraping should be performed prior to starting antimicrobial therapy. Agars that are plated routinely include blood and chocolate agars; other media, such as Löwenstein-Jensen, are plated only if prompted by clinical suspicion.[4][5]
Result
blood agar: most bacteria; chocolate agar: Haemophilus species, Neisseria species; non-nutrient agar with Escherichia coli overlay: Acanthamoeba species; Lowenstein-Jensen medium: mycobacteria species, Nocardia species; thioglycolate broth: aerobic and anaerobic bacteria
Tests to consider
CBC
Test
Abnormal values indicate presence of systemic infection or immune compromise. Not obtained routinely.
Result
expected to be within normal limits
HIV test
Test
Obtain if uncommon infections, such as microsporidiosis, are suspected as this may indicate immunosuppression.
Result
expected to be negative; positive in HIV infection
autoimmune testing
Test
If peripheral ulcerative keratitis is suspected, test for possible underlying disorder (e.g., rheumatoid factor, antineutrophil cytoplasmic antibodies, and anti-double-stranded DNA antibody).
Result
may be positive if underlying condition present
corneal scraping: polymerase chain reaction (PCR) testing
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