Refractionist _YasirButt on Instagram: "NYSTAGMUS. Nystagmus is an involuntary, rhythmic oscillation of the eyes. The movements may be horizontal, vertical, or rotary, and can affect one or both eyes. 🔍 Definition Nystagmus is a condition in which the eyes move repeatedly and uncontrollably, often reducing visual acuity and depth perception. 🧠 Types of Nystagmus 1️⃣ Physiological (Normal) Nystagmus Occurs in normal individuals: Optokinetic nystagmus – when watching moving objects (e.g., train)