Chloroquine or hydroxychloroquine (Fenral) is a common drug used to treat immune system disorders such as systemic lupus erythematosus, rheumatoid arthritis, and dry syndrome. Hydroxychloroquine is effective and safe for most patients, but for a small number of patients, hydroxychloroquine is sensitive to side effects, including gastrointestinal reactions, rash, dizziness and headache, and nervousness. The most serious side effects of hydroxychloroquine are mainly in the form of eye lesions, which often result in loss of vision and black shadows in front of the eyes. The lesions can disappear after early detection of eye changes and timely discontinuation of the drug. Chloroquine or hydroxychloroquine drug? Toxic retinopathy was first reported in 1996 and is mainly manifested as cycloplegic pigment changes around the macula, also known as bull’s-eye maculopathy (BEM). With advances in medical research and observation of patients on long-term hydroxychloroquine medication, physicians now generally do not need to wait for structural changes in the retina to detect retinal changes early and assess the systemic effects of the medication through ocular conditions. Ophthalmic examinations include visual field, multifocal electroretinography, optical coherence tomography (SD-OCT), and fundus autofluorescence. Ophthalmic examinations are now required whenever hydroxychloroquine is used to assess side effects and to guide dose reduction or discontinuation of the drug. Generally, the side effects of the drug are related to the dose and duration of use, and patients are advised to visit the ophthalmologist for a six-month or yearly examination. Hydroxychloroquine is a prescription drug and patients must use the drug under the guidance of a physician and not change it without permission, which will also help reduce some of the side effects that can occur when taking hydroxychloroquine.