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Eye Diseases



The eye is a special sense organ that consists of multiple layers and chambers, and provides organisms with vital information about the environment. Because the eye is in direct contact with the air, it is continually exposed to microorganisms including pathogens. The eye has many ways of protecting itself from harm, including physical barriers, such as the eyelid, and chemical barriers, such as enzymes in tears. Eye infections can be caused by a variety of pathogens such as bacteria, viruses, and helminths (parasitic worms), and are responsible for conditions such as conjunctivitis and eye worm infection.

At A Glance

  • The anatomical features of the eye include the sclera, iris, lens, cornea, anterior chamber, posterior chamber, conjunctiva, optic nerve, vitreous chamber, retina, eyelid, and pupil.
  • The eye's natural defenses are limited to tears, mucus, eyelashes, eyelids, and lysozymes.
  • In the eye, Corynebacterium, Staphylococcus, Micrococcus, and Streptococcus are commonly found genera.
  • Many different types of organisms may cause eye infections, while the types of infections they cause fall into four categories: blepharitis, conjunctivitis, keratitis, and dacryocystitis.
  • Conjunctivitis is an inflammatory condition of the eyelid-lining conjunctiva with numerous infectious and noninfectious causes.
  • Bacterial eye infections manifest as conjunctivitis or keratitis and require rapid diagnosis and treatment to avoid serious eye damage.
  • Few viruses infect the eyes, and they are mostly self-limiting in healthy adults.
  • Only a few genera of fungi opportunistically infect the eye, and they typically cause mild, treatable conditions.
  • Organisms from across the animal kingdom may parasitize the eye, including arthropods, protozoa, and helminths.