By Christine Yue Leonard, Senior Associate Editor O phthalmologists are no strangers to the classic red eye presentation, which tends to rear its head in the clinic on a daily or weekly basis. Typical causes include conjunctivitis, subconjunctival hemorrhage, dry eye, blepharitis, topical glaucoma medicatio ns and contact lens overwear. The full list of red-eye differentials is vast, however. Here, experts share some tips for narrowing down the cause, as well as some of the more unusual culprits behind