Here's what you should do:
1. Observe: Pay close attention to your cat's behavior. Is this a sudden change? What else is different? Are they squinting, pawing at their eyes, or exhibiting any other symptoms?
2. Contact your veterinarian immediately: Light sensitivity and hiding can be signs of a serious medical condition. Your vet needs to examine your cat to determine the cause and recommend the appropriate treatment.
3. Possible causes: Some potential causes of light sensitivity in cats include:
* Eye infections: Conjunctivitis, keratitis, and other eye infections can cause irritation and pain, leading to light sensitivity.
* Glaucoma: This condition involves increased pressure within the eye, which can lead to pain, vision loss, and light sensitivity.
* Retinal disease: Issues with the retina, the light-sensitive tissue at the back of the eye, can also lead to light sensitivity.
* Head trauma: An injury to the head can affect the nervous system and potentially cause light sensitivity.
* Certain medications: Some medications can cause light sensitivity as a side effect.
4. Provide a safe and comfortable environment: While you wait for your vet appointment, try to provide your cat with a quiet and dimly lit space to rest. Avoid bright lights and any potential triggers.
Remember: It's crucial to seek professional veterinary advice as soon as possible. Don't try to diagnose or treat your cat yourself.