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Clinical studies of vernal keratoconjunctivitis (VKC) patients show that total IgE serum levels are increased even in the absence of IgE antibodies to common allergens. Activated eosinophils are also a constant feature of VKC at both the circulation (cytofluorimetry) and tissue (tear cytoloy and conjunctival scrapings) levels. Moreover, allergen challenge induces a prologed inflammatory reaction with a prevalent participation of eosinophils, lymphocytes and possibly basophils. Immunohistochemical studies of VKC biopsies show a multicellular inflammatory infiltrate with prevalence of activated eosinophils, mast cells and CD4 lymphocytes in both epithelium and subepithelium. Mediator studies indicate that eosinophil products (eosinophil peroxidase, eosinophinal cationic protein and eosinophil-derived neurotoxin/eosinophil protein X) are increased in both serum and tears, where tryptase and interleukin (IL)-5 are also detectable in higher amounts than in controls. On the basis of these findings, we postulate that VKC can represent a phenotypic model of up-regulation of the cytokine gene cluster on chromosome 5q which through its products (IL-3, IL-4, IL-5 and granulocyte/macrophage-colony-stimulating factor) regulates Th2 prevalence, IgE production as well as mast cell and eosinophil growth and function in VKC.

Overall, the test-retest variability of Cirrus HD-OCT is good for the central and sectorial macular subfields, with a low incidence of scan artifacts.

Purpose: To explore and compare the influence of optic disc size on the diagnostic accuracy of retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) quantitative assessment.Design: Observational, cross-sectional evaluation of diagnostic tests. Participants: We included 120 eyes from 50 normal subjects and 70 glaucomatous patients classified by the presence of a repeatable visual field defect for the analysis.Testing: The RNFL thickness was measured by scanning laser polarimetry with variable corneal compensator (GDx-VCC, Carl-Zeiss Meditec, Dublin, CA) and spectral-domain optical coherence tomography (Cirrus HD-OCT, Carl Zeiss Meditec, Inc). We obtained ONH imaging by means of confocal scanning laser ophthalmoscopy (HRT3; Heidelberg Engineering, GmbH, Dossenheim, Germany).Main Outcome Measures: Sensitivity and specificity for normative classifications, sensitivity at fixed specificity and area under the receiver operating characteristics curve (AUC) for continuous parameters. A logistic marginal regression model and coefficients of variation (CoV) have been used to test and quantify the influence of optic disc size on the diagnostic accuracy of the 3 technologies under investigation.Results: Among continuous parameters average RNFL thickness for Cirrus HD-OCT, nerve fiber indicator for GDx-VCC and cup shape measure for the HRT3 showed the best diagnostic accuracy with an AUC of 0.97, 0.94, and 0.94, respectively. Among normative classifications, the highest sensitivity and specificity were found for OCT average RNFL thickness (75.8% and 94.7%), for GDx superior thickness (77.1% and 97.5%), for HRT3 Moorfields regression analysis result (89.4% and 73.7%) and for HRT3 GPS global (92.3% and 76.5%). The diagnostic performance of HRT3 parameters seemed to be significantly influenced by optic disc size, although the same was not true for Cirrus HD-OCT and GDx VCC. The most steady performers for each imaging device across disc size groups were Cirrus HD-OCT average thickness (CoV, 1.6%), GDx-VCC inferior thickness (CoV, 2.5%), and HRT3 GPS temporal and nasal (CoV, 21.4%).Conclusions: The diagnostic accuracy of quantitative RNFL assessment as performed by Cirrus HD-OCT and GDx-VCC is high and virtually unaffected or only minimally affected by the size of the optic disc and may provide more consistent diagnostic outcomes across small and large discs than ONH assessment as performed by HRT3. Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article.