What is meridia of eye?

Meridia of the eye, also known as pupillary meridia, refers to the variation in the position of the pupils in relation to the center of the lens of the eye. The pupil is the black circular opening in the center of the iris (the colored part of the eye), which regulates the amount of light that enters the eye.

Each eye may have its own meridian (axis) of the pupil, which can be determined by measuring the distance between the center of the lens and the center of the pupil. The meridians of the pupils can affect the quality of vision, especially in patients with astigmatism.

In a normal eye, the pupillary meridian is usually aligned with the visual axis, which is the imaginary line connecting the fovea (the part of the retina responsible for sharp central vision) and the center of the pupil. However, in some cases, the pupillary meridian may deviate from the visual axis, resulting in a condition called pupillary meridional amblyopia. This condition can cause visual distortion and reduced visual acuity.

The pupillary meridia can be measured using specialized instruments, such as the pupillometer or the autorefractor. Accurate assessment of the pupillary meridia is important in the diagnosis and management of vision disorders such as astigmatism, anisometropia (unequal refractive error between the two eyes), and other visual abnormalities.