Visual hallucinations: A review for ophthalmologists

Visual hallucinations (VH), as opposed to illusions (which are misperception of a real visual stimulus), are a false sense of perception without external visual stimulation. The content of VH is highly variable and can range from simple unformed images (e.g., flashing lights or steady spots and colored lines) or shapes (geometric hallucinations) to formed hallucinations (e.g., vivid objects, flowers, animals or even people). In this review, we describe the common etiologies and the differentiating features for VH of interest to ophthalmologists.