Investigations
1st investigations to order
rapid adenovirus immunoassay
Test
Positive in adenovirus infection.[51][52][53] Ten-minute office immunoassay test for diagnosing adenovirus in tear fluid sample. One visible control line is negative; 2 visible lines indicate a positive result.[49][54] The sensitivity of these immunoassays is between 85% and 93%, and the specificity is between 94% and 99%.[49][54]
Result
2 visible lines equal positive
Investigations to consider
cell culture
Test
Most accurate and reliable test; may take 1 to 3 weeks for a result.[55][56][57] Cell culture has a sensitivity of 91% and specificity of 100%.[54] Most patients are not routinely sent for these studies, because of the length of time required to obtain a result.[55][56] The use of these tests should be considered for chronic forms of infectious conjunctivitis to confirm the pathogen.
Conjunctival cultures should be performed in all neonates with suspected infectious conjunctivitis.[1]
Result
bacterial or viral isolation
special stains (Gram, Giemsa)
Test
Gram staining is used in hyperacute conjunctivitis to identify gram-negative diplococci (Neisseria gonorrhoeae).[22]
Smears for cytology and special stains (e.g., Gram, Giemsa) should be performed in all neonates with suspected infectious conjunctivitis.[1]
Result
visualisation of bacterial organisms
polymerase chain reaction
Test
Very sensitive; typically requiring 1 to 4 days for a result.[60][61][62] Mostly used for investigational purposes. Most patients are not routinely sent for these studies, because of the length of time required to obtain a result.[55][56] The use of these tests should be considered for chronic forms of infectious conjunctivitis to confirm the pathogen.
Result
amplified viral or bacterial DNA
ocular pH
Test
In cases of suspected chemical splash injury, ocular pH should be tested and eye irrigation continued until pH is 7.
Result
target pH is 7
allergy skin testing
Test
Allergy skin testing may be useful in more severe allergic conjunctivitis. Allergy skin testing may identify specific allergens to target with immunosuppression.[1]
Result
identification of specific allergen(s)
tear immunoglobulin E level
Test
Measuring tear immunoglobulin E levels may be useful in more severe allergic conjunctivitis. Tear immunoglobulin E may help to diagnose allergic conjunctivitis and assess its severity.[1]
Result
level of immunoglobulin E in tears
Use of this content is subject to our disclaimer