Allergic
conjunctival diseases (ACDs) are inflammatory diseases of the conjunctiva and cornea caused predominantly by the
IgE-mediated
immediate hypersensitivity response. Allergic
conjunctival diseases include
allergic conjunctivitis,
vernal keratoconjunctivitis (VKC), atopic
keratoconjunctivitis (AKC), and
giant papillary conjunctivitis. In clinical practice of ACDs, an ocular
allergy test using
biomarker measurement is a crucial examination technique for diagnosing, evaluating severity, and determining the efficacy of medical treatment. The ocular
allergy test includes the tear test for evaluating the concentration of
biomarkers in tears and an ocular surface test for assessing the expression levels of messenger
ribonucleic acid (
mRNA)
biomarkers on the ocular surface. The clinical usefulness of several
biomarkers has been demonstrated in patients with ACDs; specifically,
eosinophil cationic protein and
eotaxin-2 as eosinophilic
inflammation biomarkers;
interleukin-4 and
thymus and activation regulated chemokine (CCL17/TARC) as Th2
inflammation biomarkers; eotaxin,
tumor necrosis factor-alpha and soluble
IL-6 receptor as giant papillae
biomarkers; and
osteopontin and
periostin as allergic
inflammation and remodeling
biomarkers. Furthermore, the ocular
allergy test, quantitative evaluation methods using
biomarkers have allowed for better understanding of the immunological and pathophysiological mechanisms of ACDs. Therefore, the search for a
biomarker is important to make an ocular
allergy test useful. In previous ocular
allergy tests, the
biomarkers for allergic
inflammation in patients with chronic ACDs including VKC and AKC were substantial. However, the selection of
biomarkers associated with the early phase reaction of
immediate hypersensitivity and innate immunity responses needs to be addressed in future investigations.