Chorioretinitis and Optic Neuritis

Rhea V. Morgan, DVM, DACVIM (Small Animal), DACVO

BASIC INFORMATION suspected, blood pressure can be measured. In eyes that are cloudy Description and cannot be examined well, an ultrasound may be performed. Inflammation of the tissues of the back of the eye (choroid, retina) If a brain disorder is suspected, computed tomography (CT scan) is called chorioretinitis . The choroid is part of the uvea of the eye, or magnetic resonance imaging and a spinal tap may be recom- so inflammation of the choroid may be called posterior uveitis . mended. The cause of chorioretinitis and/or optic neuritis can be Involvement of the nerve leading from the eye to the brain is called difficult to find and may require numerous tests. optic neuritis . These conditions may occur alone or together and are inherently serious because they affect vision. TREATMENT AND FOLLOW-UP Causes Treatment Options With the exception of trauma to the eye, these conditions are usually manifestations of a systemic or generalized problem. The Treatment involves administering medications for the eye problem choroid and retina are commonly affected by other diseases within and for any underlying causes. Medications applied to the eye do not the body, and optic neuritis may arise with certain disorders of the reach the retina and choroid but topical anti-inflammatory drugs (usu- brain. Numerous causes must be considered: ally steroids), pupil dilators/pain relievers (such as atropine), and anti- • More than 25 different infections can cause this inflamma- biotics may be used for inflammation in the front part of the eye. tion, including fungal, tick-borne, bacterial, viral, protozoal, Once an underlying cause is determined, appropriate treat- and parasitic infections. Some types occur more often in dogs, ment is started for that condition. Examples include antibiotics, whereas others are more common in cats. anti-fungal agents, drugs for hypertension and blood disorders, • In rare instances, the immune system may attack the uvea, and and chemotherapy for certain tumors. Oral anti-inflammatory other parts of the body may also be affected. agents can reach the retina, choroid, optic nerve, and brain, but • Tumors may arise within the eye or metastasize to the eye from the administration of steroids is often delayed until infectious dis- elsewhere in the body. eases are ruled out and a specific cause is determined. • Hypertension (high blood pressure), anemia, kidney disease, Removal of the eye may be recommended in cases of sus- sugar diabetes, elevated blood protein levels, and other blood pected intraocular tumors, blind eyes that remain painful, eyes that disorders may be causes. develop unresponsive glaucoma, or concern that an infection may persist in the eye and spread to other parts of the body (especially Clinical Signs certain fungal infections). Inflammation confined to the back of the eye may not be visible and may not be discovered until the animal is examined for other Follow-up Care signs of illness. Inflammation that also affects the front of the eye Chorioretinitis and optic neuritis often indicate the presence of can cause the eye to be red, cloudy, and painful (squinting). Vision a serious underlying disease. If treatable, these diseases usually may be affected, resulting in pupils of different sizes. If both eyes require prolonged therapy (months), periodic recheck visits, and are inflamed, the animal may act blind. The onset of blindness can careful monitoring. Certain laboratory tests may be repeated to be quite sudden (within days). monitor for side effects associated with the oral drugs used to treat these conditions. Diagnostic Tests Report any worsening of signs, particularly the onset of pain Diagnosis of these conditions can be difficult without specialized (squinting) or decreased vision, to your veterinarian immediately. instruments to examine the back of the eye. If the diagnosis cannot be Prognosis confirmed, your veterinarian may refer your pet to a veterinary oph- Whether chorioretinitis or optic neuritis will resolve often depends thalmologist or neurologist for further evaluation. A complete physi- on the underlying cause, the severity of the inflammation, and the cal examination is usually performed to search for any other changes diligence of the treatments. Many cases improve with adequate that may signify the presence of a generalized (systemic) problem. therapy, but permanent scarring within the retina may result in Laboratory tests are frequently done to search for infections blindness. Some forms of optic neuritis improve with treatment but and underlying causes. Chest and abdominal x-rays and an abdom- are not cured, so therapy must be continued for the life of the ani- inal ultrasound are sometimes recommended. If hypertension is mal. Some of the causes of these conditions are life-threatening.