From time to time, some patients complain that when they look at something, they feel like watching an abnormal TV screen with a sense of “water ripples” and an abnormal reflection. Patients often think it is because of the recent fatigue, so the eyes are temporarily discomfort, to the ophthalmology consultation is often a long delay, or the symptoms have been serious enough to affect the quality of life. In fact, this watery feeling is a characteristic manifestation of a fundus disease —- “chorioretinitis”, which is more common in women. The term choroid may sound odd, but it has a big role to play. If we compare our eyes to a camera, the choroid is the tissue that keeps the film functioning properly. There are many possible causes of choroiditis, and it is important to identify them whenever possible, because treatment options for choroiditis vary widely from cause to cause, and if the wrong treatment is chosen, it may not only delay the condition, but may even add fuel to the fire. Therefore, once the possibility of chorioretinitis is suspected clinically, a thorough examination is needed to determine the cause and severity of the inflammation. This includes ocular coherence optical tomography, fundus photography, fundus fluorescence angiography, and ocular ultrasound, which can suggest the extent of the lesion and possible etiology from different angles. In addition, there are various immune-related serum laboratory tests to exclude rheumatic immune diseases and various infection-related factors, such as tuberculosis, syphilis, etc., to exclude infectious causes. When the cause of chorioretinitis cannot be determined through routine testing, intraocular fluid testing should be considered because systemic laboratory indicators, even if abnormal, do not indicate the source of fundus disease. The test of intraocular fluid includes two major aspects, one is the detection of antigen and antibody levels of various pathogenic microorganisms, which is a direct indication for the identification of the cause of fundus disease, and the second is the detection of inflammatory factor concentration, which indicates the degree of activity of intraocular inflammation; in the treatment process, it can indicate whether the treatment is on the right path. As long as the regular medical institutions and experienced ophthalmologists to operate, the extraction of intraocular fluid is very safe and time is fast.