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Background: Conjunctival provocation test (CPT) is used to demonstrate clinical relevance to a specific allergen. Blomia tropicalis (Bt) is a prevalent allergen in tropical regions. Its major allergen Blo t 5 is commonly detected in house dust in Brazil. Patients with allergic rhinoconjunctivitis (ARC) have IgE antibodies to Bt although it may not indicate clinical allergy.Objective: The purpose of this study is to demonstrate the role of CPT in clinical allergy to Bt in allergic conjunctivitis (AC).Methods: CPT was performed in asymptomatic subjects with ARC (n = 26) outside the grass pollen season. They had positive skin prick tests (SPT) to Bt and other common inhalant allergens and they were off topical or systemic antihistamines. Standardized allergens were used for CPT (Blo t 5 462.5 ng/mL in 1:1 solution, Alk Abelló). CPT was conducted on a control group of subjects (n = 29) without symptoms of ARC and with negative SPT. CPT was performed with progressive doses of allergen solutions in normal saline (1:32, 1:16, 1:8, 1:4, 1:2). CPT with the same allergen dose that elicited a positive reaction was repeated one week later. The protocol was approved by the local Ethics Board and signed informed consent was obtained from all participants.Results: There were 92% (24/26) of positive CPT in subjects sensitized to Bt. Significant association was found between SPT and CPT results with Bt (p < 0.0001). CPT had 92% sensitivity and 100% specificity when compared to SPT results. Positive reactions with the same dose or one immediately higher occurred in 21 out of 22 subjects who repeated TPC 1 week later. Mild transient nasal symptoms (21/24) were the major side effects of positive CPT followed by moderate periorbital edema which occurred in 41% (10/24). One controlled asthmatic BT-sensitized subject developed wheezing and dyspnea during a positive CPT with Bt that cleared with inhaled albuterol (400 mcg). There were no reactions whatsoever of CPT in non-allergic subjects.Conclusion: This study demonstrated that Bt may cause allergic conjunctivitis in our population. In addition, CPT is a safe and reproducible test if standardized allergens are used.

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BackgroundNon-allergic environmental factors may cause ocular symptoms in atopic and non atopic subjects, which are known as nonspecific conjunctival hyperreactivity (CHR). This study aims to investigate the presence of CHR to the HCPT in subjects with ocular symptoms.Methods63 adults with ocular symptoms (itching, red eyes or tearing) were selected and tested for allergy to house dust mites and grass pollen by skin prick tests (ALK Abelló) and serum specific IgE (Immunocap-Phadia). They were considered atopic if these tests were positive to at least one allergen and non atopic if tests were negative. HCPT with 10-fold serial diluted glucose solutions was performed in all subjects until it produced conjunctival redness. Digital images were analyzed by 2 investigators (MD and technician) registering redness of the challenged eyes in red and the total area of contra-lateral eyes in blue using the fine brush tool (software GIMP 2.6.5). The number of red dots of the affected eye (%) was compared to the number of blue dots of the control eye.ResultsTPCH was positive in 33/38 atopic subjects (87%) and in 4/25 non atopic (16%). Most reactions occurred at the 40% glucose solution. Sensitivity was 87% and specificity 84% (P < 0.0001). There was a significant correlation (96.5%, Pearson, P < 0.0001) between the number of red dots reported by investigators in 23 digitalized images.ConclusionsTPCH identifies CHR in both atopic and non atopic subjects. Atopic subjects exhibit CHR more frequently than non-atopic subjects. Digital images may be useful for grading ocular hyperemia in TPCH.

BackgroundDiagnosis of allergic conjunctivitis (AC) is based on symptoms and positive skin prick test (SPT) to common aeroallergens. Allergens identified by SPT may not be clinically relevant to the eye. This study aims to compare the skin and conjunctival allergic responses to dust mites and grass pollen.Methods56 subjects (29 ± 11.4 years) with ocular allergy and sensitized to dust mites and/or grass pollens were recruited for the study. Standardized extracts of Dermatophagoides pteronyssinus (Der p 1 83.8 mcg/mL), Blomia tropicalis (Blo t 5 462.5 ng/mL) and Lolium perenne (Phl p 5 399.2 mcg /mL) were used for skin test end point titration. Increasing 2-fold allergen dilutions were tested in forearms until no skin reaction was elicited. The end point was considered the dilution immediately above that one. Conjunctival provocation test (CPT) was performed with progressive doses of allergen (1:32, 1:16, 1:8, 1:4, 1:2) to the involved allergen. All tests were performed after obtaining written informed consent and out of grass pollen season. Subjects should be assymptomatic and off antiallergic medication.ResultsOf 82 conjunctival tests (30 Lp; 26 Bt; 26 Dp), 76% (62/82) occurred with 1:8 to 1:2 dilutions, 18% (15/82) with 1:32 to 1:16 dilutions and 6% (5/82) were negative. CPT were positive in 76% of subjects with Der p 1 (10.5–41.9 mcg/mL), Blo t 5 (57.8–231.3 ng/mL) and Phl p 5 (49.9–199.6 mcg/mL). SPT were positive for allergens with 1:1024 to 1:128 dilutions in 22% (18/82), with 1:64 to 1:16 dilutions in 63% (52/82) and with 1:8 to 1:2 dilutions in 11% (9/82). Three subjects had negative SPT. Allergen threshold dose to trigger a response in the skin was lower than in the eye for all 3 allergens tested (P < 0.0001).ConclusionsReactivity to aeroallergens in provocation tests requires higher allergen dose for CPT than SPT. Positive SPT with standardized allergenic extracts is predictive of clinical relevance in the diagnosis of allergic conjunctivitis.