fˈɜːst, ɪt ɹˌɛpɹᵻzˈɛnts ɐ mᵻkˈænɪkəl ænd tˈaɪt bˈæɹiɚ wˌɪtʃ sˈɛpɚɹˌeɪts ðɪ ˈɪnɚ spˈeɪs ʌvðɪ ˈaɪ fɹʌmðə blˈʌd stɹˈiːm.
First, it represents a mechanical and tight barrier which separates the inner space of the eye from the blood stream.