Psittacine Bird Ophthalmology: A Review of Anatomy, Physiology, Diagnostics, and Interventions.

Parrots (Psittaciformes) comprise a large group of approximately 400 species of birds. There are currently no comprehensive reviews of parrot ophthalmology in the peer-reviewed literature. This review describes the unique ocular variations of parrots, including visual ability and anatomic adaptations. A comprehensive summary of ophthalmic diagnostic tests, including aqueous tear measurements, tonometry, conjunctival cytology, conjunctival microbiology, and ocular ultrasonography, in clinically normal psittacine birds is presented. Common ocular disorders of parrots and their treatments are discussed. Aqueous tear production can be measured using Schirmer tear tests, phenol red thread tests, and endodontic absorbent paper point tear tests. Intraocular pressure is best measured with a rebound tonometer; however, applanation tonometry has also been described. Conjunctival cytology, conjunctival microbiology, and ocular ultrasonography are useful in determining disease etiopathology. Topical neuromuscular blocking agents may be effectively used with caution to induce pharmacologic mydriasis in psittacine birds. Ongoing research should be performed on all available psittacine bird species to increase sample size and available data from which normal reference intervals can be determined.