Blog | Optical Industry Insights, Guides & Tools for Opticians

Anti-reflective coating eliminates lens reflections through thin-film interference, improving light transmission and visual clarity. Here is how it works, who benefits most, and how it compares to blue-light and other coatings.

Eye floaters are usually benign, but a sudden shower of new floaters or accompanying flashes of light can signal a retinal tear or detachment, a sight-threatening emergency that requires same-day evaluation by an ophthalmologist.

When a patient says ‘I’m seeing double,’ one question separates a correctable optical problem from a medical emergency. This guide shows optical staff how to triage diplopia and refer appropriately.

Pupillary distance (PD) is the measurement in millimeters between the centers of your two pupils. To measure it yourself, stand 18 inches from a bathroom mirror, hold a millimeter ruler flat against your brow, align the zero mark over your right pupil center, then close your right eye and read the mark that falls overContinue reading “How to Measure Your Pupillary Distance (PD): Ruler, Mirror, and App Methods”

The numbers stamped on a frame, such as 52□18-140, are the boxing system: eye size, bridge and temple length in millimeters. This guide decodes every frame measurement (A, B, DBL, ED), shows how they set frame PD and decentration, and how to tell whether a lens will physically fit.

There is a published answer to how accurate a PD, lens power and optical center have to be. ANSI Z80.1 and ISO 21987 set the tolerances a finished pair of glasses must meet. This guide gives the exact numbers and what they mean for measurement at the dispensing desk.

Prentice's rule, prism equals decentration in centimeters times lens power, quantifies the unwanted prism created when the optical center is not in front of the pupil. This guide covers the formula, base direction, worked examples, and the vertical imbalance that anisometropia produces in down-gaze.

Monocular PD measures nose-bridge to each pupil individually; binocular PD is the total pupil-to-pupil distance. Near PD is smaller than distance PD due to convergence. This reference explains all four measurements, when each is required, and how conversion estimates work for dispensing.

Pupillary distance grows through childhood and stabilizes in adulthood. Learn when PD actually changes, why near PD differs from distance PD, and when re-measurement is worth doing.

A dispensing pupillometer is an optical instrument that measures interpupillary distance (PD) by projecting a coaxial light source onto the cornea and aligning crosshairs with the resulting corneal reflex in each eye. A digital model adds an electronic scale readout, eliminating the manual sliding cursor and giving the dispenser a precise numeric value for bothContinue reading “Digital Pupillometer: How It Works, Accuracy vs Manual, and the Smartphone Alternative”