Laboratory Studies
Culture of the cornea should be performed to rule out infectious etiology.
A complete laboratory evaluation for suspected systemic disorders is performed.
Laboratory studies for rheumatoid arthritis include the following:
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Erythrocyte sedimentation rate (ESR)
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C-reactive protein (CRP) level
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Complete blood cell (CBC) count
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Rheumatoid factor (RF) assay
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Antinuclear antibody (ANA) assay
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Anti−cyclic citrullinated peptide and anti−mutated citrullinated vimentin assays
Laboratory studies for granulomatosis with polyangiitis include the following:
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CBC: Mild normochromic normocytic anemia is present in 50% of patients; leukocytosis is common, with a neutrophil predominance
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Elevated inflammatory markers (ESR, CRP)
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Abnormal kidney function test findings (blood urea nitrogen and creatinine) and urinalysis (UA) results in patients with renal involvement
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Rheumatoid factor is positive in a low titer in two thirds of patients
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Cytoplasmic antineutrophil cytoplasmic antibody (c-ANCA) directed against PR3 is most specific for GPA
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Some patients with GPA express perinuclear-staining ANCA (p-ANCA) specific for myeloperoxidase (MPO)
Mooren ulcer: In order to arrive at this diagnosis, an exhaustive laboratory examination should be performed and must be nonconclusive for other possible explanations of corneal ulcer, as follows:
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Laboratory investigations include CBC count with differential, platelet count, ESR, CRP, rheumatoid factor, ANA, ANCA, complement fixation, C3, C4, LFTs, VDRL/FTA-ABS, BUN and creatinine, serum protein electrophoresis, urinalysis, hepatitis B surface antigen, hepatitis C virus antibody, and HIV antibody.
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Cultures should be performed to rule out bacterial, fungal, and viral (eg, herpes simplex virus [HSV]) causes.
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A deficiency of suppressor T cells has been found in the serum of a patient with Mooren ulcer, while another study showed a helper T cell/suppressor cell ratio of greater than 1:1 in 6 of 9 patients with Mooren ulcer. More recent studies have shown that most of the resident cells from specimens with Mooren ulcers express the class 2 antigens, human leukocyte antigen DR (HLA-DR), or human leukocyte antigen DQ (HLA-DQ). Another study demonstrated that sera from patients with Mooren ulcer had high antibody titers to a cornea-specific stromal protein antigen. [6]
Systemic lupus erythematosus: Of patients with SLE, 50-60% have antibodies to cardiolipin. For the importance of the measurement of intraocular pressure, see Yazici et al. [37] The American College of Rheumatology has suggested 11 classification criteria for SLE. Patients are considered to have SLE if they meet 4 of the following criteria:
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Malar rash
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Discoid rash
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Photosensitive rash
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Oral ulcers
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Nonerosive arthritis in 2 or more joints
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Pleuritis or pericarditis
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Glomerulonephritis or proteinuria
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Seizures or psychosis
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Hemolytic anemia, leukopenia, lymphopenia, or thrombocytopenia
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Immunologic laboratory abnormalities, such as antibodies to double-stranded DNA or the SM antigen or a false-positive serologic test for syphilis
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Positive ANA test that is not caused by a medication
Scleroderma: Anti-Sci-70 antibody tests and anticentromere antibodies (CREST variant)
Laboratory studies for polyarteritis nodosa include the following:
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Elevated blood urea nitrogen level or creatinine level
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Presence of hepatitis B surface antigen or antibody in serum
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Arteriographic evidence of aneurysms or occlusions (nonarteriosclerotic)
Histologic Findings
In RA-associated paracentral corneal ulcerations, sparse T-lymphocytes consistently were identified in the subepithelial areas adjacent to the ulcer, with some neutrophils and macrophages in the stroma. B-lymphocytes were not detected. On 2 specimens in this immunology study, [38] some infiltrating cells and the corneal endothelium expressed MHC class II antigens reactivity.
In granulomatosis with polyangiitis, histologic findings include necrotizing, granulomatous vasculitis with infiltrative neutrophils, lymphocytes, plasma cells, histiocytes, and giant cells.
In polyarteritis nodosa, the presence of polymorphonuclear cells in artery walls can be found on biopsy of small- or medium-sized arteries.
Imaging Studies
Ultrasonography of the eye (B-scan) can be used to evaluate for posterior scleritis, often present concurrently in patients with corneal ulcer associated with autoimmune diseases.
Pertinent imaging studies to assess for auto-inflammatory disorders include the following:
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CT scanning of the sinuses (GPA)
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Chest radiography (sarcoidosis)
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MSK radiography of affected joints (RA)
Other Tests
Corneal scraping for cultures may be performed when an infectious etiology is suspected.
