What does PD stand for in lens measurements?

What does PD stand for in lens measurements?

• A. Pupillary Distance
• B. Prism Distance
• C. Pupil Diameter
• D. Palpebral Distance

Answer: (A)

Pupillary Distance is the horizontal distance between the centers of your pupils. This measurement is essential when making glasses because it positions the lens’s optical centers directly in front of your pupils, so your eyes look through the correct part of the lens. Accurate PD helps you see clearly with minimal distortion and prevents eye strain, headaches, or blurry vision, especially with high prescriptions or progressive lenses. PD is typically measured in millimeters and can be given as a single binocular value (distance between the centers of both pupils) or as two monocular values (the distance from the bridge of the nose to each pupil center). In practice, frames are chosen with this measurement in mind to ensure proper alignment of the lenses with your pupils. The other terms don’t fit because pupil diameter refers to how big your pupil opens, palpebral distance relates to the eyelid opening, and prism distance isn’t a standard lens-fitting measurement.

Pupillary Distance is the horizontal distance between the centers of your pupils. This measurement is essential when making glasses because it positions the lens’s optical centers directly in front of your pupils, so your eyes look through the correct part of the lens. Accurate PD helps you see clearly with minimal distortion and prevents eye strain, headaches, or blurry vision, especially with high prescriptions or progressive lenses.

PD is typically measured in millimeters and can be given as a single binocular value (distance between the centers of both pupils) or as two monocular values (the distance from the bridge of the nose to each pupil center). In practice, frames are chosen with this measurement in mind to ensure proper alignment of the lenses with your pupils.

The other terms don’t fit because pupil diameter refers to how big your pupil opens, palpebral distance relates to the eyelid opening, and prism distance isn’t a standard lens-fitting measurement.