What Does Pd 60/57 Mean

Overview

The notation “Pd 60/57” is frequently encountered on eyeglass prescriptions, particularly for bifocal or progressive lenses. “Pd” stands for pupillary distance, the distance in millimeters between the centers of the two pupils. The two numbers—60 and 57—represent separate measurements: the first (60 mm) is the distance PD used for viewing objects far away, and the second (57 mm) is the near PD used for reading or close-up tasks. This dual measurement accounts for the slight inward convergence of the eyes when focusing on nearby objects, ensuring that the optical centers of the lenses align with the wearer’s line of sight in both distance and near vision.

History / Background

The practice of measuring pupillary distance dates back to the early days of modern optometry in the 19th century, when precise lens centering became recognized as essential for effective vision correction. Initially, a single PD measurement was used for all distances. However, as bifocal and later progressive lenses gained popularity in the mid‑20th century, optometrists observed that a single PD led to discomfort and visual distortion during near tasks. This led to the adoption of separate distance and near PD measurements. The notation “Pd 60/57” (or similar pairs such as 64/61) became a standard shorthand on prescription forms, particularly in the United States and Europe. Today, it is a routine part of comprehensive eye examinations for patients who require multifocal lenses.

Importance and Impact

Correct pupillary distance measurement is critical for the performance of eyeglasses. An inaccurate PD can cause eyestrain, headaches, blurred vision, and even double vision because the lenses’ optical centers do not align with the pupils. The impact is especially pronounced in high‑power prescriptions and progressive lenses, where even a 1–2 mm error can degrade visual comfort. The use of separate distance and near PD values (like 60/57) acknowledges the physiological convergence of the eyes, improving the wearer’s ability to transition smoothly between viewing distances. This practice has contributed to higher satisfaction rates among bifocal and progressive lens users and has become a quality standard in the optical industry.

Why It Matters

For anyone ordering eyeglasses—especially bifocals, trifocals, or progressive lenses—understanding the Pd 60/57 notation helps ensure the prescription is correctly interpreted by the lab. Consumers who purchase glasses online should be aware that some retailers only request a single PD; providing the dual measurement (if prescribed) can improve lens accuracy. Additionally, individuals experiencing discomfort with new glasses may find that their PD was measured or entered incorrectly. Knowing the meaning of “Pd 60/57” empowers patients to verify their prescription details and communicate effectively with eye care professionals.

Common Misconceptions