Role of Giemsa Staining in the Diagnosis of Viral Conjunctivitis (Pink Eye) Viral conjunctivitis usually does not require laboratory tests for diagnosis. However, if it is recurrent or severe in chronic infections, then sample should be taken for Giemsa staining. This test utilizes conjunctival scrapes to conclude the character of inflammatory response. Polymorphonuclear cells indicate bacterial infection whereas mononuclear cells indicate viral infection.