A Sight for Sore Eyes: Ophthalmic Emergencies
Clara Williams, DVM, DACVO
Proptosis, “eye out of the socket,” is the forward displacement of the globe out of the orbit with subsequent entrapment of the eyelids behind the eye. It occurs due to trauma to the head, usually a dog fight. Dogs with wide eyes and shallow orbits are at higher risk. Cats and long-nosed dogs require very severe trauma for the eye to proptose.
Factors to consider before replacing the eye into the orbit:
- Time elapsed since injury
- How many extraocular muscles are ruptured (no more than three)
- Presence of hyphema
- Whether or not the the globe is soft
If the decision is made to replace the globe in the orbit, it should be done immediately. The patient should be stable enough for a short period of general anesthesia. After the area is prepped, infiltrate the lateral canthus with local anesthesia, then perform a lateral canthotomy. This will enlarge the palpebral fissure immediately and allow grasping of the skin on the upper and lower eyelids with Allis forceps; pull gently up and over the globe. Once the eyelids are manipulated over the globe, the eye returns to the orbit. Suture the lateral canthotomy and place a temporary tarsorrhaphy to protect the globe during the first two weeks postsurgery. Topical antibiotic, oral analgesia and anti-inflammatories are in order. Postoperative deviation of the globe occurs due to rupture of extraocular muscles. Strabismus often diminishes over weeks to months.
Glaucoma, increased pressure within the eye beyond that compatible with normal ocular function, vision and comfort, is one of the leading causes of blindness in animals and people. It is caused by a disturbance in the flow of fluid within and out of the globe. Once one eye has been affected by primary glaucoma, the second eye will normally be affected within two years. Other causes of glaucoma include inflammation, trauma and intraocular tumors. Glaucoma patients often present with a painful eye and decreased vision. Other presenting complaints include injected conjunctival and episcleral vessels, gray uneven discoloration of the cornea, mid-range mydriatic pupil and elevated intraocular pressure. Glaucoma is one of the ophthalmic conditions with severe visual implications and should be referred to a veterinary ophthalmologist for further management. It is rarely cured, and many animals lose vision despite medical and surgical treatment.
An accurate diagnosis of glaucoma is based on a thorough ocular examination and measurement of the intraocular pressure (IOP) with a tonometer. Normal IOP should be lower than 20-25 mmHg. Acute glaucoma is an ophthalmic emergency and must be treated immediately! If the pressure remains elevated for a few hours, permanent vision loss occurs. The combination of the carbonic anhydraze inhibitor, dorzolamide, and a beta blocker, timolol, works very well together with the prostanoid analogue, latanaprost.
Lens luxation into the anterior chamber may be seen with elevated intraocular pressure or not. It is a true ophthalmic emergency that requires surgery. Prompt surgical removal of the luxated lens is recommended if prognosis for vision is good.
The normal lens position is behind the pupil. When luxation occurs the lens may be displaced completely in front of the pupil (anterior luxation) or behind the pupil to the back of the eye (posterior luxation). The luxation can also be partial (incomplete or subluxation). Lens luxation is observed in young adult dogs usually 4 – 5 years of age. Primary lens luxation is common in terrier breeds such as the wirehaired fox terrier, Jack Russell terrier, Sealyham terrier, Tibetan terrier and terrier crosses. The breeds predisposed to this condition are border collie, Australian blue heeler, German shepherd dog and Shar Pei. Primary lens luxation is bilateral, although the onset of luxation varies between the eyes. Secondary lens luxation and subluxation may occur after the globe has increased in size (buphthalmia) in glaucoma cases or after chronic intraocular inflammation (uveitis, cataracts).
Anterior lens luxation usually manifests with acute tearing (epiphora) and eye pain and redness. Cloudiness of the cornea is present if the intraocular pressure is elevated (glaucoma). If the cornea is clear, the luxated lens can be observed in front of the pupil. The luxated lens can migrate back and forth through the pupil.
Corneal ulcers start as simple superficial ulcers that become deeper. One should be worried if the ulcer is deep (descemetocele) and there is a risk of rupturing. Topical antibiotics and pain management, topical atropine, oral analgesics and anti-inflammatories, are recommended. Use of an E-collar is also recommended. An uncomplicated ulcer should heal within 7 to 10 days. If healing takes longer, the ulcer may be indolent and require debridement and grid keratotomy.
Corneal abscesses occur when a corneal ulcer gets infiltrated by bacteria. The corneal stroma may be greenish yellow and become malacotic or gelatinous. Bacteria such as P. aeruginosa and S. betahemolyticus are involved in progression of the ulcer. Clinical signs of a stromal abscess include increased tearing, severe ocular pain, redness and evidence of a whitish to yellow discoloration of the cornea.
A stromal abscess is an ocular emergency, although it may not require immediate intervention by an ophthalmologist. You can stabilize the eye by establishing strong, frequent (every 2 hours) topical antibiotic therapy (quinolones), anticollagenases (serum, EDTA), systemic antibiotics (Clavamoxâ or Unasynâ) and analgesia. It is often necessary to admit these patients for 24 hours. Surgical repair of the cornea (conjunctival flap) may be necessary if the ulcer progresses to deep layers, and the eye is at risk of perforation or has already perforated.
Uveitis occurs when the uveal tract, rich in vascularization, gets inflamed. Protein, red and white cells leak to the usually transparent intraaocular fluid, making it turbid. The condition may be present in one or both eyes. Bilateral involvement is seen more frequently in patients with infectious, parasitic, neoplastic or autoimmune diseases.
There are many causes of uveitis; it is frequently considered an ocular manifestation of a systemic disease. Among the causes are trauma, cataract formation, infections and tumors. Some of the infections in dogs include Rocky Mountain spotted fever, Lyme disease, ehrlichiosis, anaplasmosis, infected uterus, viral hepatitis and systemic fungal infections. In cats the causes include feline leukemia virus (FeLV), feline immune deficiency virus (FIV), feline infectious peritonitis (FIP), toxoplasmosis and bartonellosis.
Symptoms of uveitis include eye pain, squinting, redness, tearing, elevation of the third eyelid, cloudiness of the cornea and a small pupil. On occasions there is pus or blood inside the eye.
Diagnosis of uveitis requires a complete systemic workup to include blood and urine testing and thorax and abdomen imaging; however, approximately 60% of the cases are a diagnosis of exclusion. Possible sequela include attachment of the pupillary opening to the lens capsule, secondary glaucoma (high intraocular pressure), secondary cataract formation and retinal detachment. The eye may become blind and painful in which case surgical removal (enucleation) will be recommended. Emergency treatment should include topical eye medication to control intraocular inflammation, analgesia, systemic anti-inflammatories and antibiotics, and possibly medications to prevent glaucoma. If there are no corneal ulcers prednisone acetate and atropine are recommended.