The early symptoms of the disease will be reflected in a certain part, and the cat’s eyes are also connected to the blood circulation and metabolism of the whole body. Some systemic diseases will show signs from the eyes, or some diseases will start from the eyes. Local infection slowly spreads throughout the body. Typically, there are two types of diseases: infectious diseases and immune-mediated diseases. 1. Infectious diseases 1. Diseases transmitted by ticks Infection with Rickettsia and Borrelia burgdorferi can cause conjunctivitis, subconjunctival hemorrhage, anterior uveitis, posterior uveitis, retinochoroiditis, retinal hemorrhage, and optic neuritis. However, animals with eye lesions only account for 10 to 15% of the total sick animals. Taking conjunctivitis as an example, after a cat suffers from conjunctivitis, the affected eyes will appear swollen, the conjunctiva will be flushed, the eyelids will be closed, and there will be bloody and purulent secretions. Kittens often have bloody and purulent secretions that glue their eyes together and make them unable to open their eyes. Acute catarrhal conjunctivitis, the secretion is thin or mucus; chronic catarrhal conjunctivitis, the secretion is very little, and the eye pain is not obvious; purulent conjunctivitis, the secretion is mucopurulent , the eyelids are often glued with blood and pus. Optic neuritis in cats is also a common disease. The clinical manifestations are: ① Vision loss: Most of the time, vision suddenly decreases, and even reduces to light perception or no light perception within a few days of onset. ②Drawing-like pain at the back of the eyeball when the eyeball is turned, and tenderness in the deep orbit. ③ Fundus changes: During papillitis, the optic disc is congested, slightly bulged (less than 3D), the edges are unclear, the physiological depression disappears, the retinal veins are filled and tortuous, the retina around the optic papilla is edema and turbid, flame-like hemorrhage and yellow-white exudation. In acute retrobulbar optic neuritis, the fundus of the eye is basically normal in the early stage, but the color of the optic papilla becomes pale and the optic nerve atrophies in the late stage. ④Melan-100 glare test shows that the pupillary reflex completely disappears under glare, red light and blue light, indicating optic nerve inflammation or optic chiasm tumor. So when we find that our cat is bitten by a tick, we should do the following: ① When you find a tick staying on the skin, do not pull it hard to prevent secondary damage to the skin caused by tearing the tissue or breaking the mouthparts. You can apply chloroform, ether, kerosene, turpentine or dry smoke on the head of the tick and wait for the tick to fall naturally from the skin.​ ② Disinfect the wound. If the mouthpart is broken into the skin, surgery should be performed to remove it.​ ③ There is 0.5% procaine local sealing around the wound.​ ④ Antihistamines and corticosteroids can be given when symptoms of systemic poisoning occur. When tick bite fever and tick paralysis are discovered, in addition to supportive therapy, corresponding symptomatic treatment and timely rescue are provided. 2. Histoplasmosis Eye lesions with this fungal disease are blepharitis, uveitis, retinochoroiditis, granulomatous retinal detachment and optic neuritis. For cat blepharitis, the symptoms are: ① Tearing: Caused by stimulation of the trigeminal nerve, which causes the reflex of tear secretion to increase, or the hypertrophy of the eyelids causes pressure on the tear points. ② Flushing and swelling around the palpebral fissuresThick.​ ③Blepharospasm.​ ④ Hair loss around the palpebral fissure, sometimes not visible in the acute stage.​ ⑤Chip falling.​ ⑥Scab formation. When a fungal or parasitic infection is suspected, treat as for dermatomycosis, feline mange, and demodicosis. Let’s talk about uveitis again. Uveitis is the most common eye disease in cats and can often cause chronic pain in the eyeballs and even blindness. Feline uveitis is not just an eye disease, it is associated with many systemic diseases. Uveitis in cats exhibits a number of clinical signs. For example: photophobia, epiphora, redness in the whites of the eyes, abnormal pupil size and outline, abnormal iris color, intraocular bleeding, etc. A specific affected eye may present with more than one of the above symptoms. The most terrible thing about uveitis is that it can lead to glaucoma, which can quickly lead to blindness in animals. The main principles of treatment are local and systemic anti-inflammatory drugs (Dianbis, prednisone), drugs to prevent secondary glaucoma (timolol), and drugs to relieve lens spasm (atropine). 3. Toxoplasmosis Serologically, 79% of cats with uveitis were seropositive for Toxoplasma gondii. However, in serological tests of healthy cats, the probability of being positive for Toxoplasma gondii is also very high. At the same time, Toxoplasma gondii may not always be found in cases with uveitis and positive Toxoplasma serology. Toxoplasma gondii lives on the intestinal mucosa of cats, and cats are the final host of Toxoplasma gondii. Domestic cats can become infected with Toxoplasma gondii during their lifetime, usually by eating dead mice, moles, squirrels or other infected small animals. Cats that live entirely indoors and have never been exposed to rats may never become infected. Cats suffering from toxoplasmosis can be treated with clindamycin (10 to 15 mg per kilogram of body weight, taken orally every 12 hours for 2 to 4 weeks), which has a certain effect. The combination of sulfa drugs and antibacterial synergists has the best effect. It is best to use medication at the early stage of the disease. Applying medication later can make the symptoms disappear, but it cannot kill the cysts in the tissues and make the animals become carriers of worms. Use sulfadiazine + trimethoprim, the former 7 mg/kg, the latter 14 mg/kg, double the first dose, take orally twice a day, for 3 to 4 days. Conditions improved within 24 to 48 hours after starting treatment. Neurological conditions, especially lower limb motor neuron defects and muscle atrophy, can take several weeks to subside. When this disease causes uveitis, it can be treated locally or systemically with corticosteroids. There is no need to worry that corticosteroids will worsen the condition. Cats infected with Toxoplasma gondii that also have FeIJv or FIV have poor cure rates. 2. Immune-mediated diseases The main disease in cats is cutaneous uveitis syndrome, which usually causes uveitis lesions in the front and back of both eyes, often accompanied by serous retinal detachment. The disease will only occur in the pigmented eyes, so when the affected animal has one blue eye and one brown eye, the disease may occur in one eye.For brown eyes with pigmentation. At the same time, the skin all over the body is accompanied by whitening of the hair color, and depigmentation of the nose, soles, mouth and eyelids.