The Maddox rod is a cylindrical lens with parallel rods that convert a point source of light into a streak or line. It’s used in ophthalmology and optometry to assess and measure strabismus (misaligned eyes) and heterophoria (latent strabismus).

How it works:

1. Light source: A point source of light is shone through the Maddox rod.
2. Streak formation: The rods convert the light into a streak or line, which is perceived by the patient.
3. Alignment assessment: The orientation and position of the streak relative to the other eye help diagnose and quantify deviations in eye alignment.

Types of Maddox rods:

1. Single Maddox rod: Used to assess horizontal or vertical deviations.
2. Double Maddox rod: Used to assess torsional deviations.

Clinical applications:

1. Strabismus diagnosis: Helps diagnose and quantify esotropia, exotropia, hypertropia, and other types of strabismus.
2. Heterophoria diagnosis: Detects latent strabismus, which can cause eye strain or other symptoms.
3. Treatment planning: Guides treatment decisions, such as prism correction or strabismus surgery.

The Maddox rod is a valuable tool in ophthalmology and optometry, enabling practitioners to accurately diagnose and manage strabismus and heterophoria.