고양이 안내 종양 자주 묻는 질문 Q&A — 보호자가 꼭 알아야 할 핵심

What if a tumor develops inside a cat’s eye? — What are the early symptoms and diagnostic methods?

Eye HealthQ&AMeongsiljang Veterinary Advisory Board

Feline intraocular tumors can lead to vision loss if not detected early. Here’s a summary of the key information pet owners should know.

What are feline intraocular tumors?

A medical illustration showing the internal structure of a cat’s eye and the location of intraocular tumors.

Feline intraocular tumors are growths that develop inside the eye, particularly within the uveal tissues—such as the iris, ciliary body, and choroid—or other internal structures of the eyeball. These tumors vary widely in type, ranging from benign adenomas to malignant adenocarcinomas, as well as uveal lymphomas, which often occur alongside systemic diseases. They are primarily reported in older cats. Because these tumors may not cause obvious changes on the surface of the eye, regular ophthalmic examinations are essential for early detection. - Varied nature: The spectrum of tumors ranges from benign adenomas to malignant adenocarcinomas and lymphomas, making a biopsy necessary to determine the specific nature of the growth. - Potential systemic connection: Uveal lymphoma frequently accompanies systemic disease, meaning ocular symptoms may appear before other signs of illness become evident. - At-risk groups: These tumors are mainly seen in senior cats. Additionally, some reports indicate that Siamese cats have a higher risk for certain epithelial eye tumors. - Importance of diagnosis: Even if the eye appears normal, regular ophthalmic check-ups are recommended to identify potential risks early.

Why are feline intraocular tumors not detected early?

Feline intraocular tumors often show few outward signs in their early stages, making them easy for pet owners to overlook. Moreover, because cats tend to hide discomfort, abnormalities are frequently noticed only after significant changes have occurred inside the eye. In cases associated with systemic diseases, such as uveal lymphoma, ocular symptoms may even be the first clinical signs to appear. - Subtle early changes: Initial signs may be limited to corneal edema or mild uveitis, which are easily mistaken for simple inflammation. - Difficulty in expression: Cats rarely show pain or discomfort, leading owners to recognize changes late. - Lack of owner awareness: Even when the eye appears largely normal, neglecting regular check-ups can result in missed opportunities for early detection. - Overlooking warning signs: Dismissing symptoms like cloudiness or redness of the eye can delay diagnosis and treatment.

A cat appearing disoriented and confused due to vision problems.

What are the main symptoms of intraocular tumors?

In cats with intraocular tumors, you may notice several changes, such as corneal edema (clouding of the cornea), anterior uveitis, irregular pupil shape (pupillary distortion), thickening or deformation of the iris, and a red appearance of the eye due to hyphema (bleeding in the anterior chamber). As the condition progresses, it can lead to glaucoma, retinal detachment, and vision loss, so a veterinary examination is necessary if any changes are observed. - Corneal and ocular clouding: The eye may appear cloudy due to corneal edema. - Pupil and iris changes: The pupil may become irregularly shaped (pupillary distortion), and the iris may thicken and deform. - Bleeding and inflammation: The eye may appear red due to hyphema or uveitis, and pus (hypopyon) may be visible. - Changes upon progression: Vision may decline due to glaucoma or retinal detachment. Consult a veterinarian immediately if symptoms appear.

A photo showing a cat with cloudiness in the eye and dilated pupils.

Comparison of intraocular tumor stages by symptom

Item	Mild	Moderate	Severe
Eye/Vision	Mild corneal clouding	Persistent corneal edema, uveitis	Risk of vision loss from glaucoma or retinal detachment
Eye Appearance	Nearly normal	Pupil deformation, thickened iris	Hyphema, hypopyon, eyeball deformation
Systemic/Behavioral	No change	Discomfort in the eye	With uveal lymphoma, may be accompanied by weight loss and lethargy

Official staging is assessed not only by symptoms but also by tumor size and the presence of lymph node or distant metastasis. If changes are observed, it is important to get an early ophthalmic examination.

How is diagnosis performed?

Feline intraocular tumors are diagnosed by examining the internal structures of the eye through ophthalmic exams and ocular ultrasound. These methods allow for detailed observation of the eye’s interior, helping to determine the tumor’s location and size. However, fine-needle aspiration (FNA) cytology alone cannot reliably distinguish between benign (adenoma) and malignant (adenocarcinoma) tumors, so a histopathological examination (biopsy) is required for a definitive diagnosis. - Ophthalmic and Ultrasound Exams: Ophthalmic exams and ocular ultrasound help identify the tumor’s location and size. - Cytology and Histopathology: Cytology cannot definitively differentiate between benign and malignant tumors, so a biopsy is necessary to confirm the tumor’s nature. - Additional Testing: If systemic involvement is suspected, as in lymphoma, additional imaging and systemic tests are performed to check for metastasis. - Professional Diagnosis: Accurate diagnosis requires a thorough examination by a veterinarian. Early diagnosis aids in developing an effective treatment plan.

A veterinarian examining a cat's eyes with a specialized retinal scanner

Signs requiring immediate veterinary visit

If your cat’s eyes suddenly become cloudy or red, or if the pupils appear irregular in shape, seek veterinary care immediately. Bleeding or pus inside the eye, as well as signs of ocular discomfort, are also warning signs. If there is a sudden decline in vision or suspicion of glaucoma, prompt treatment is essential. Delaying care can make restoring vision difficult.

What are the treatment options?

The treatment approach depends on the tumor type, size, location, and degree of malignancy. Small, superficial lesions can often be managed with laser or radiation therapy. If the tumor is large, highly malignant, or if preserving vision is not feasible, enucleation (surgical removal of the eye) may be necessary. For conditions like uveal lymphoma, which can be associated with systemic disease, comprehensive systemic examinations are recommended before and after treatment. - Laser and radiation therapy: For small, superficial tumors, laser or radiation therapy may be used to inhibit growth or remove the lesion. - Enucleation: If vision cannot be preserved or the tumor is highly malignant, the eye may be surgically removed to reduce the risk of metastasis. - Systemic examination: If systemic involvement is suspected, such as with lymphoma, a full-body examination is performed to check for spread to other organs. - Recurrence monitoring: Regular follow-up exams are essential after treatment to monitor for recurrence or metastasis. Your veterinarian will help determine the appropriate ongoing care plan.

Points to note: Post-treatment care

After surgery, it is important to administer antibiotics to prevent infection. Additionally, your cat should wear an Elizabethan collar to prevent them from scratching their eyes. Regular veterinary check-ups are necessary to monitor for recurrence and assess whether the condition has metastasized.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently asked questions

Can feline adenomas be genetic?

Some reports suggest that certain epithelial eye tumors carry a higher risk in Siamese cats. However, the genetic predisposition to intraocular tumors in general has not yet been clearly established, and most cases are linked to various factors, including age.

Are intraocular tumors exclusive to cats?

No, it can occur in both dogs and cats. It is most commonly seen in older animals.

Can intraocular tumors be cured?

Early detection and appropriate treatment can lead to a better prognosis. However, if the condition is malignant or associated with systemic diseases, there is a risk of recurrence or metastasis.

Can it be prevented?

Regular eye exams are the most practical way to catch problems early. We especially recommend routine check-ups for senior cats.

How does a cat’s life change after an eye removal surgery?

Most cats can live their daily lives without significant issues even if they lose one eye, as they adapt well using their remaining eye.

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