Understanding the Cat’s Third Eyelid: When It Can Heal Itself
Cat owners may notice a mysterious pink or whitish membrane suddenly appearing at the inner corner of their pet's eye. This is the third eyelid, or nictitating membrane. While it’s usually hidden from view, it plays several vital roles in ocular health. Understanding its function, when its visibility is a concern, and when it may resolve without intervention is key to ensuring your cat’s wellbeing.
What Is the Third Eyelid?
The third eyelid is a protective fold of tissue located in the inside corner of the eye. Its key responsibilities include:
- Protecting the eye from injury and debris
- Lubricating the cornea by producing part of the tear film
- Helping fight infections via lymphoid tissue
While movement of this membrane is involuntary, it may briefly appear when your cat is sleepy, frightened, recovering from anesthesia, or experiencing eye discomfort.
When Is Seeing the Third Eyelid Normal?
There are benign reasons the third eyelid might be visible:
- Sleep or sedation: Temporary elevation is common after napping or waking from surgical anesthesia.
- Haws syndrome: Symmetrical elevation of both third eyelids, often tied to mild gastrointestinal disturbances, typically resolving with no specific treatment.
In such cases, the third eyelid generally returns to its normal position without intervention.
Causes Requiring Veterinary Attention
Persistent protrusion of the third eyelid may signal more serious conditions:
- Eye injuries such as scratches or ulcers
- Infections — viral, bacterial, or fungal conjunctivitis
- Cherry eye (prolapse of the third eyelid gland)
- Horner’s syndrome — a neurological disorder causing one-sided eyelid droop, pupil constriction, and globe retraction
- Systemic illness including dehydration or fever
- Allergic or chemical irritants
- Nerve damage in the facial or cervical region
If additional symptoms like discharge, swelling, pain, or behavior changes are present, seek veterinary care immediately.
Diagnostic Process
A veterinarian will conduct a thorough eye examination, which may include:
- Ophthalmoscopic examination
- Fluorescein staining for ulcers or abrasions
- Intraocular pressure testing
- Tear production measurement
- Phenylephrine challenge (to assess Haws syndrome)
- Blood and urine tests to pinpoint systemic causes
- Imaging, if neurological involvement is suspected
Treatment Options
Treatment is based on the underlying cause. Options include:
- Observation for temporary issues like Haws syndrome or sleep-induced protrusion
- Topical antibiotic or antiviral eye drops for infections
- Anti-inflammatory medications for irritation or trauma
- Surgery in the case of cherry eye
- Treatment of systemic illness such as fluid therapy for dehydration
- Neurological management if Horner’s syndrome is diagnosed
In some mild cases, especially with Haws syndrome or if linked to sleep or sedation, no treatment is required and the eyelid returns to normal within days to weeks.
Home Care and Prevention
- Inspect your cat’s eyes regularly for redness, discharge, or swelling
- Keep your cat indoors to minimize trauma and infections
- Trim nails to prevent self-inflicted eye injuries
- Clean the area gently with a moistened cotton ball if there's discharge
- Never use human medications on your cat without veterinary approval
- Keep new cats quarantined to prevent infectious spread
Routine veterinary checkups are essential for maintaining eye health. Prompt attention to changes in your cat’s eye appearance may prevent complications or vision loss.
Conclusion
In summary, a cat’s third eyelid may heal by itself when associated with temporary non-serious causes like Haws syndrome, sleep, or minor GI upset. However, persistent protrusion or symptoms such as discharge, swelling, or vision changes always merit a visit to the vet. Early diagnosis and treatment are key to preserving eye health and comfort. Stay observant and proactive to keep your feline friend’s vision clear and bright.
