TL;DR: A white spot on a cat's lens is often caused by cataracts or normal aging and typically requires a veterinary exam within a week. However, if the eye is red, painful, or vision loss is sudden, seek urgent care immediately.
What causes a white or opaque spot on my cat's eye?
When you notice a white or cloudy spot specifically on your cat's lens, it is often a sign of cataracts. Cataracts occur when the proteins in the lens clump together, preventing light from passing through clearly. Another common cause, especially in senior cats, is nuclear sclerosis—a normal aging process that gives the lens a bluish-grey tint but doesn't usually cause blindness. Less commonly, it could be a sign of inflammation (uveitis) or previous trauma.
Is a white spot on my cat's eye a veterinary emergency?
- Urgency level: In most cases, the urgency is low because lens changes typically develop slowly and are not painful.
- Routine care: You should schedule a veterinary exam within the next week to monitor the condition.
- Emergency signs: Seek immediate care if the eye is red, your cat is squinting, or there is sudden vision loss, as these may indicate secondary glaucoma or inflammation.
How does taking a photo help my veterinarian triage my cat?
- Assessment of depth: A clear, close-up photo helps a professional see if the spot is on the surface (cornea) or deep inside (lens).
- Determining cause: Visual evidence helps the vet identify the potential cause before you even leave your home.
- Appointment timing: High-quality images help determine the necessary speed of the follow-up appointment.
Clinical Context (Merck Veterinary Manual)
An opacity of the lens or its capsule is defined as a cataract, which must be differentiated from minor lens imperfections seen in young animals and normal nuclear sclerosis in older animals. Cataracts are classified by age of onset, anatomic location, cause, degree of opacification, and shape. In cats, cataracts are most frequently secondary to anterior uveal inflammation and are often observed in young animals. Penetration of the anterior lens capsule requires lens removal as soon as possible because escape of lens material causes gradually intensifying lens-induced uveitis that often progresses to secondary glaucoma and phthisis bulbus.
Chapter: Ophthalmology, Emergency
Source: The Merck Veterinary Manual, 11th Edition (Page 1697)