«مَا دَعَاكَ إِلَى التَّعَامِي؟»
What prompted you to feign blindness?
Al-Ḥārith is not asking for a medical diagnosis; he asks why a sighted man adopted the appearance of blindness. Taʿāmī, a form-V verbal noun, expresses assuming or simulating blindness and must be distinguished from actual ʿamā.