“…In chronic forms a remodeling process is induced in conjunctiva tissue as fibrosis with vascularization that can be easily identified with slit lamp (Ono & Abelson, 2005) There are numerous classifications for AOD according to the underlying pathophysiology and clinical findings. Common signs and symptoms exist in the different types of allergic disorders with frequent overlapping between SAC, PAC (acute forms of allergic conjunctivitis), VKC and AKC (chronic forms of conjunctivitis); therefore, classifications are recommended to standardize disease based on signs and symptoms, (mild, moderate or severe), (Abelson et al, 1990;Uchio et al, 2008;) length of the disease (acute vs chronic disease), mechanism of immunopathogenesis (EPR and LPR stages), and duration of episodes activity (quiescent, intermittent and persistent), only suggested to VKC and AKC (Bonini et al, 2007;Calonge & Herreras, 2007), since they impact the quality of life. Such matter is important and should be consider in AOD diagnosis, similar to other allergic diseases (Del Culvillo et al, 2010).…”