Wild birds rely heavily on perfect, or near perfect, vision to fly, capture prey, avoid predators, and find suitable perches and shelter. Eye issues, which can appear as ocular lesions, can be indicative of different systemic disorders. While perfect vision is not as vital for captive companion birds, recognizing and treating ocular disease is important for their overall health and wellbeing. Our team at Veterinary Vision Center wants to explain what conditions frequently affect companion birds and how these issues should be addressed.
Eye exam procedures in birds
A bird’s eye is anatomically and physiologically different from a mammal’s eye, but the examination approach is similar to that used in mammalian ophthalmology and includes:
- Tear tests — The Schirmer Tear Test and the Phenol red thread test are used to determine whether a bird’s eyes are producing adequate tears.
- Fluorescein staining — Applying topical fluorescein sodium and examining a bird’s eye with a cobalt blue light can reveal corneal damage such as ulceration, lacerations, and punctures, as well as lacrimal apparatus obstructions.
- Tonometry — A tonometer assesses a bird’s intraocular pressure based on normal values that have been established for numerous avian species. Topical anesthesia is typically applied to the bird’s cornea before the intraocular pressure is measured.
- Mydriasis — Dilating the pupil (i.e., mydriasis) is necessary to evaluate the back part of a bird’s eye. However, the drugs commonly used for this task in mammals are not effective in avian patients because their intraocular muscles react differently. Heavy sedation or general anesthesia can be used to dilate the pupil, and neuromuscular blocking agents also can be used. However, these agents can have serious adverse effects if not properly administered.
- Imaging — X-rays can be used to evaluate soft tissue swelling around a bird’s eye, as well as displaced skull fractures. Ultrasonography can show structures inside a bird’s eye and detect conditions such as retinal detachment. Computed tomography and magnetic resonance imaging also can provide diagnostic information about a bird’s eye and surrounding structures.
- Cytology and culture — Swabs from the conjunctival sac and corneal scrapings can be collected for cytology and microbiologic culture.
- Electroretinography — This technique is useful when assessing a bird’s retinal function.
Common eye diseases in birds
Many issues can affect your bird’s eyes, and certain systemic conditions can appear as ocular problems. Ocular diseases that affect birds include:
- Conjunctivitis — Conjunctivitis is a common eye disorder seen in companion birds and can be caused by bacterial infections, viral agents, parasites, fungal infections, trauma, and foreign bodies. In addition, conjunctivitis is a sign of many other medical problems in birds, including respiratory infections and vitamin A deficiency. Signs include swollen, red eyes, eye or nostril discharge, facial swelling, sensitivity to light, cloudy or glassy eyes, and blindness. Blood and swab samples are typically needed to isolate the underlying factor. Treatment generally includes saline flushes and topical antibiotic therapy. Oral medications may be necessary in some cases. After treatment, blood and swab samples may need to be collected again to ensure your bird has fully recovered. Practicing good hygiene and sanitation can drastically reduce your bird’s risk of developing conjunctivitis.
- Avian pox virus — Species-specific avian pox virus is the most common cause of viral conjunctivitis in birds, and it also can cause corneal inflammation (i.e., keratitis). The virus is transmitted by biting insects, such as mosquitoes, mites, fleas, and flies, as well as through contact with an infected bird or contaminated objects like bird feeders. Wart-like growths on a bird’s unfeathered skin, including their eyelids, is the most common clinical sign. Secondary bacterial infections are common, and sequelae such as lid deformities, corneal vascularization, and cataracts can occur. No cure is available for avian pox, and treatment is aimed at preventing secondary bacterial infections.
- Vitamin A deficiency — Vitamin A is important for a bird’s immune system to remain healthy. Birds fed a diet exclusively of seeds and nuts tend to have a vitamin A deficiency. Signs include white spots in a bird’s eyes, sinuses, and in and around their mouth. Supplementing their diet with vitamin A typically resolves the problem. Foods rich in vitamin A include papaya, cantaloupe, chili peppers, broccoli leaves, turnips, sweet potatoes, carrots, spinach, egg yolks, and liver.
- Uveitis — Uveitis is an inflammation of the inside of a bird’s eye caused by issues such as trauma, infections, immune-mediated diseases, and cancer. Signs include light sensitivity, squinting, cloudy cornea, and pupil constriction. Treatment is aimed at reducing inflammation and addressing the underlying cause. Topical antibiotics and topical anti-inflammatory agents are often recommended.
- Cataracts — Cataracts occur when the lens’ opacity increases, leading to vision loss. Cataracts in birds are caused by such factors as advanced age, genetics, infection, trauma, and diabetes. Signs include eye cloudiness, inability to find their perch, and rubbing or scratching at their eyes. Many birds blinded by cataracts can continue to lead a satisfactory and comfortable life. Lens luxation and retinal detachment can occur secondary to cataract formation, and your bird’s eyes should be regularly examined if they have cataracts.
- Glaucoma — Glaucoma is not commonly diagnosed in birds, but this may be because measuring the intraocular pressure in a small bird’s eye is difficult. Birds can be affected by this condition, however, and signs include blood inside the eye, light sensitivity, and pupil constriction. Glaucoma medications commonly used in mammals have not been evaluated in birds. Since glaucoma is a painful condition, affected birds should have their eye removed.
If your bird has a closed eye, or eye swelling, redness, or discharge, have them evaluated immediately by a veterinarian. These signs can indicate a significant problem. If your bird has a condition affecting their eye, contact our Veterinary Vision Center team so we can help save their sight.