Dental erosion is characterized by progressively destroyed teeth, which has no relation to bacteria but to chemicals. Some internal factors, such as gastroesophageal reflux induced by bulimia, anorexia, gastrointestinal diseases, or drugs, and external factors, such as diet, drugs, and occupational acid exposure, are considered promotive factors for this disease. This article presents a patient suffering from severe dental erosion in the whole dentition, especially in the maxillary teeth, due to gastroesophageal reflux induced by glucocorticoid therapy for optic neuritis. This article discusses the mechanism between optic neuritis glucocorticoid therapy and dental erosion.