Feline Ophthalmology Series

May 14, 2026

Part One: Feline Corneal Ulcers  

Susan Cook Henry

If you have never had a cat experience a corneal ulcer, consider yourself fortunate. Though most common in brachycephalic breeds of cats or those with shorter muzzles and more prominent eyes, it can happen to any cat. You might notice your cat squinting one eye more than normal with more tearing than normal. And then, the cat may start frantically and aggressively rubbing that eye with a paw: The cat is definitely in pain, the eye appears sensitive to light, and the conjunctival tissues have become red and swollen. A close look at the surface of the eye (the cornea) may show cloudiness and/or a “crater” of sorts: a delineation of what looks like something is missing on the surface. You have just discovered that your cat may have a corneal ulcer. Please note: the following information is NOT a substitute for veterinary intervention; however, products and treatments mentioned have been very helpful for use with my own cats and those of breeder colleagues working in tandem with a veterinarian or veterinary ophthalmologist. Failure to treat quickly and properly could lead to serious complications, leading to loss of vision or even loss of the eye.

The feline eye (or any eye, for that matter) is a complex assembly of structures and fluid. The cornea is the outermost layer of the eye itself, covering the pupil and the iris, and protecting the eye from dust, germs, and other unwanted intrusions such as eyelashes or fur. It also “controls the amount of light that enters the eye, thus facilitating accurate vision.”¹ Any cloudy areas will prevent light from properly entering the interior of a cat’s eye and distort or preclude proper vision.

Although the cornea is normally a strong and durable structure, its tissue is sensitive and subject to a number of intrusions. Most common of these is the “excessive loss of cells in the outermost layer of tissue (epithelium) covering the cornea.”¹ When these epithelial cells are destroyed, a shallow crater-like area may appear which is often visible with a keen eye.

The destruction of these cells can be caused by a variety of conditions: perhaps starting with a scratch, an ingrown eyelash, dirt trapped beneath the lid, or exposure to caustic chemicals (think antiseptic/antiviral sprays at shows that may be improperly mixed and are too strong or a drop of soap splashed from a bath). However, the most common cause of corneal ulcers is the feline herpesvirus (FHV-1). This viral infection is unique to cats, but not contagious to people or dogs. Yet it is highly contagious to other cats and is often passed to very young kittens from their mothers. Once infected, a cat will carry it throughout its lifetime, and many cats become carriers. The virus often presents with upper respiratory issues, though most common are corneal ulcers.²

Diagnosis

Any problems with a cat’s eye are serious, but symptoms such as those described above require immediate attention, preferably from a veterinary ophthalmologist. Your first reaction when seeing your cat with eye distress may be to choose an eye medication containing steroids, which are known to reduce pain and inflammation — STOP!!! At no time should ANY eye medication containing a corticosteroid be put in a cat’s eye without prescription or instruction by a veterinarian or veterinary ophthalmologist. These meds may appear to make the eye feel better at first, but they actually suppress the immune response to the injury and can make it worse. Avoid these if you see them on eye drop labels: prednisolone acetate (1%), dexamethasone, and hydrocortisone.

A tentative clinical diagnosis is made by means of application of “eyedrops containing a dye called fluorescein. If an ulcer is present, the dye will bind to any damaged tissue, leaving a clearly visible greenish coloration on the ulcerated area.”¹ Once confirmed, the veterinarian will prescribe eye medications which likely combat both bacterial and viral infections. In addition, oral medications to combat herpesvirus may be prescribed.

Treatment

There are products available online without a prescription that can be applied immediately upon suspicion of a corneal ulcer. Such products include Oculenis™ BioHance™ Ocular Repair Gel 3ml and Oculenis™ XL Corneal Repair Gel 10ml. Same product, with different packaging; both preservative-free. [https://domespharma.us/products/oculenis-biohance-ocular-repair-gel/] These lubricating products contain no antibiotics, yet make use of a low concentration of Hyaluronic Acid, which is healing and protective until a definitive diagnosis is made. These products are very similar to Remend®,  which is available by prescription only.

Another more recent product is Optixcare® Eye EMS [https://www.drugs.com/vet/optixcare-eye-ems-can.html], an Extracellular Matrix Substitute using RTGA® (ReGeneraTing Agent) technology, which lubricates and promotes corneal healing while reducing pain in the eye. It can be used in lieu of canine or feline blood serum drops while assisting the healing of a corneal ulcer.³ This product has five one-use vials, administered every other day for 10 days. It is used in conjunction with prescribed ocular antiviral/antibiotic drops to aid in faster healing of the ocular surface.

Use of these products prior to a veterinary visit will not harm a cat’s eye, but will offer comfort and give a head start to healing before a positive diagnosis can be made. Having these items on hand at home and in your show kit is recommended.

In addition to these products, you must begin combatting potential viral and/or bacterial infection. The most common eyedrops prescribed are Tobramycin, Ofloxacin, Moxifloxacin, and Cidofovir. All but the latter are usually on hand at veterinary/feline ophthalmology clinics; Cidofovir is currently not FDA-approved for veterinary use, therefore it is chemically-compounded and prescribed through compounding pharmacies and is targeted primarily at feline keratitis/ulcers caused by feline herpesvirus (FHV-1).⁴ Tobramycin counters bacteria only, so is not an effective treatment for herpes-related ulcers. Ofloxacin is commonly used to treat eye ulcers; however, it is also an antibacterial product. Moxifloxacin is effective in treating bacterial conjunctivitis. Erythromycin ointment can also be prescribed as an antimicrobial agent for conjunctivitis and corneal ulcers; however, “Its use in veterinary medicine is considered ‘off label’ or ‘extra label.’ Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions carefully.”⁵

The ointment can provide a degree of comfort beyond drops because it offers more lubrication. Whenever administering any of these eye medications, it is important to wait at least five minutes between each dose. The number of drops and times per day is something best discussed with your veterinarian.

Additionally, a regimen of the antiviral Famciclovir may be indicated in combatting corneal ulcers in conjunction with topical treatments. This is an oral medication, administered twice daily for a minimum of two weeks. The dosage is based on the cat’s weight and most likely will be either 125mg or 250mg.

Prevention

In a perfect world, there would be a perfect way to prevent corneal ulcers. There may be a genetic predisposition in some breeds, but we can do our best to provide an environment where the chances are lessened. Stress is one component which different cats handle in many ways: show halls can be a stressor for many, as can crowded conditions at home – especially when some cats antagonize others. Keeping eyes clean and free of debris is very important; using a warm, damp washcloth is ideal for removing crusty matter. There are numerous great products for cleaning eyes and helping to prevent staining. Avoiding wipes that shed cotton fibers is helpful. I have found the “Intrinsics Petite Silken 2×2 Wipes” on Amazon to be a perfect solution. And keeping eyes lubricated a couple of times per day is an added plus, especially with Persians and Exotics with their globe-shaped eyes. Lubricating drops without preservatives are key and are easily administered from resealable plastic vials.

There are some veterinarians and ophthalmologists who might suggest adding the amino acid L-lysine to your cat’s diet, based on the theory that it binds to and inhibits the amino acid, arginine, which can be responsible for the replication of the FHV-1 virus. However, …“several clinical studies with cats have shown that lysine is not effective for the prevention or the treatment of feline herpesvirus 1 infection, and some even reported increased infection frequency and disease severity in cats receiving lysine supplementation.”⁶ It has been suggested that “(d)osing is 500 mg (orally) twice daily, which should be given as a bolus and not added to food. Any benefit from lysine therapy is likely only possible with daily, lifelong treatment of cats with chronic herpetic disease, rather than use of lysine as a treatment during acute or recrudescent episodes. Potentially, daily therapy would reduce episodes of viral recrudescence.”⁷ Regardless, I continue to add a powdered L-Lysine to my cats’ wet food daily.

If you have a cat who gets a corneal ulcer, quick and proper treatment will likely lead to complete healing, often within a week or two. Lack of proper treatment could lead to a sequestrum forming, which is essentially a scab on the corneal surface as a result of a non-healing ulcer. A sequestrum may resolve itself over time, but often surgical removal is necessary which may leave scarring, requiring several months to more than a year to fully resolve.

Sources: 

1. Cornell Feline Health Center; Cornell University: https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/corneal-ulcers
2. Veterinary Specialty Center: https://www.vetspecialty.com/specialties/internal-medicine/feline-herpesvirus-fhv-1/
3. Optixcare Eye EMS use: https://vcahospitals.com/know-your-pet/optixcare-eye-ems
4. Cidofovir for Cats, developed in conjunction with Barbara Forney, VMD. Updated July 12, 2022; accessed March 2, 2026. https://www.wedgewood.com/medications/cidofovir/
5. Erythromycin Ophthalmic, Kayla Hyland DVM: https://vcahospitals.com/know-your-pet/erythromycin-ophthalmic
6. Sebastian Bol, Evelien M. Bunnick: Lysine supplementation is not effective … published November 2015; accessed March 10, 2026. https://scholars.uthscsa.edu/en/publications/lysine-supplementation-is-not-effective-for-the-prevention-or-tre/
7. Rebecca P Wilkes, Katrina Hartman: Update on Antiviral Therapies: Feline Herpesvirus Type 1; published December 2015; accessed March 10, 2026.
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