2026 Lens Disorders Complete Practice Test

Phacodonesis is the tremor of the crystalline lens caused by weakened zonular support. When the zonules are lax or disrupted, the lens can wobble with eye movements or gentle indentation, producing a visible tremor. This sign points to lens instability or subluxation and is often seen in conditions such as ectopia lentis, trauma, pseudoexfoliation, and systemic disorders like Marfan syndrome or homocystinuria. It’s important to note the difference from iridodonesis, which is a tremor of the iris due to the unstable lens; phacodonesis specifically refers to movement of the lens itself.