Numerous properties allow the eye to serve as both a potential site of influenza virus replication as well as a gateway for the establishment of a respiratory infection. Similar to epithelial cells within the human respiratory tract, human ocular tissue and secreted mucins express sialic acids, the cellular receptor for influenza viruses [14] [15] [16] . The anatomical proximity between the eye and nasal passages, notably the linkage of both systems via the nasolacrimal duct, facilitates aqueous exchange and provides shared lymphoid tissue between these sites [17, 18] . Influenza virus can rapidly spread between ocular and respiratory tissues, as was demonstrated in a recent study which detected by RT-PCR live attenuated influenza vaccine (LAIV) in nasal washes in humans within 30 minutes of experimental ocular exposure to LAIVcontaining aerosols [19] .