Emergency Care for Cat Corneal Injury: Quick Tips & Tre
The cornea, situated at the front of the eye, is a smooth and transparent structure that plays a crucial role in the eye's ability to transmit light and focus. In cats, the cornea's thickness does not exceed 1 millimeter. Being in direct contact with the external environment, the cornea is susceptible to injuries and infections. Common causes of corneal inflammation include eye injuries from other animals or foreign bodies irritating the cornea, which can lead to keratitis. In severe cases, this can result in corneal ulcers or even perforations. The healing process for corneal injuries is slow due to the lack of blood vessels in the cornea, which rely on a network of capillaries at the corneal margin and the diffusion of aqueous humor for nourishment. This can lead to poor metabolism and often results in scarring after the injury, potentially causing a decline in vision and affecting the animal's appearance.
Symptoms of keratitis include eye pain, photophobia (sensitivity to light), tearing, and cloudiness or ulcers on the cornea. When the stroma beneath the corneal ulcer is damaged, the base of the ulcer can bulge outward due to the pressure of the eye, a condition known as posterior elastic layer bulging. In cases of corneal perforation, there may be a loss of aqueous humor and prolapse of the iris.
Corneal opacity is a result of corneal edema and infiltration of white blood cells, presenting as a darkening of the superficial and deep layers of the cornea, with a decrease in transparency. The opacity may appear milky, orange, pale blue, or silvery gray. New corneal opacities often have inflammatory symptoms, appearing diffuse with no distinct boundaries. In contrast, older corneal ulcers have limited opacity with clear boundaries and may not show significant inflammation.
Keratitis can lead to conjunctival congestion and the formation of new blood vessels on the corneal surface or in its deeper layers. Superficial keratitis presents with new blood vessels that connect to the conjunctiva, forming a treelike pattern, while in deep keratitis, the new blood vessels originate from the corneal margin's capillary network, extending into the cornea in a brushlike pattern, making the source of the vessels difficult to see.
Infections with pathogenic bacteria can cause localized abscesses in the inflamed cornea, which, upon rupture, lead to ulcers. After the inflammation subsides, corneal opacities may gradually fade or disappear completely, but in severe cases, they can leave behind localized grayish opacities, which can significantly impair vision if they occur in the pupil area. After the healing of corneal ulcers, there is often a residual opacity.
The treatment for keratitis focuses on removing the cause, controlling infection, promoting inflammation resolution, and minimizing scarring. During the active phase of keratitis, appropriate antibiotics or antiviral, antifungal medications should be used to control the infection. Feline corneal ulcers are often caused by herpes viruses, and herpes eye drops should be administered four to six times a day.
To promote the absorption of corneal opacities, a 1:1 mercuric chloride and lactose mixture can be instilled into the eye. A combination of penicillin (400,000 IU), dexamethasone sodium phosphate injection (1ml), and 0.5% procaine hydrochloride (2ml) can be mixed and injected subconjunctivally and suborbicularly every other day, which can be effective for corneal opacities. The use of antibiotic eye drops (applied multiple times during the day) and ointments (used at night when the animal is resting) can enhance the effect.
For cases of corneal ulcers, while applying antibiotic treatment, 1% to 2% atropine solution can be used to dilate the pupil, allowing the eye to rest. Acetylcysteine solution (5%) can be instilled to inhibit collagen dissolution and limit the expansion of the ulcer. For refractory corneal ulcers, 2% iodine tincture or ether can be applied to the affected area, followed by rapid rinsing with saline to coagulate and remove necrotic tissue, promoting ulcer healing. In cases where the posterior elastic layer has bulged, the tissue should be carefully repaired under general anesthesia, and the cornea should be protected with a palpebral flap. The procedure involves pulling the palpebral membrane from the inner to the outer canthus, and using fine, absorbable sutures to make 3 to 4结节 sutures between the cornea and the sclera. The needle should not penetrate the entire thickness of the sclera. After surgery, the affected eye should be treated with antibiotic ointment to control infection, and the suture can be left in place for 10 to 15 days.
