What Is Demo Lenses: The Importance Of Marking When Ordering Glasses
What is markup? This is drawing on the demolding lens when ordering new glasses, the schematic designations of the center, and the height of the eye apple. This is extremely important for precision manufacturing - taking into account the markings, the craftsman will grind the lenses by shifting or not shifting the optical center, depending on the type of lens.
What Are Demo Lenses For
If you do not mark the exact location of the pupil of the eye, then the person may experience discomfort and feel significant distortions in the finished glasses, and the optical power itself on the line of sight may not correspond to the recipe. Therefore, there is no need to talk about the exact manufacture of glasses if the markings are not applied or applied incorrectly.
It may seem counterintuitive, but do not rely on the interpupillary distance (PD) in the prescription when labeling the interpupillary distance (CD) on a lens. Because the frame on the face can sit in different ways, very often there is an asymmetry of the bridge of the nose, and therefore the glasses can move left or right.
A person with the same formula may have a different distance from the center of the rim bridge to the center of the pupil on two different glasses, but the total interpupillary distance will match the prescription.
In the case of manual measurements, everything will directly depend on the skill and experience of the consultant and the technician. Measurements of pantoscopic angle, vertex distance, and frame bending angle using rulers usually give an error of one to four millimeters. While the accuracy of measurements with a tablet is approximately 0.01 mm.
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