This lecture introduces the fundamentals of prism — what it is, how it bends light to shift the perceived position of an image, and why it has become one of the neuro-optometrist’s most versatile clinical tools. We will explore how prism is prescribed within spectacle lenses to relieve diplopia, reduce asthenopia, and support visual comfort and rehabilitation in patients recovering from concussion and acquired brain injury, as well as those with longstanding binocular vision dysfunction. From there, we will move into the vision therapy room itself, showing practical examples of how prism can be utilized in exercises to develop flexibility and stamina in the binocular system, provide opportunities for patient’s to explore visual space and load visual systems to adjust the “burner” setting of a VT activity. The goal is for every therapist to leave with a clear, practical understanding of how prism functions both as a compensatory tool in glasses and as an active rehabilitative instrument in therapy.