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Nylor groove width refers to the horizontal width of the groove cut into the edge of a spectacle lens. This measurement must precisely match the thickness of the nylon cord (nylor) used in the semi-rimless frame.
read more about nylor groove width in eyeglass lenses ...The main function is to ensure a snug, non-slipping fit for the cord. If the groove is too wide, the cord will be loose, causing the lens to rattle. If the groove is too narrow, the cord cannot sit properly, leading to concentrated pressure that can crack the lens.
The lab technician must use a cutting blade that exactly matches the manufacturer's specified cord width. The goal is to create a channel that grips the cord securely enough to prevent movement but not so tightly as to pinch the lens material.
A narrow groove width is typically seen in high-end, minimalist semi-rimless frames. The narrow groove allows the use of a very thin cord, which is almost invisible when worn, maintaining the lightweight aesthetic of the frame.
An incorrectly narrow groove width the main cause of stress cracks. The tight squeeze of the cord puts immense force on the lens material, especially near the deepest point of the groove, which often results in a hairline crack originating from the edge.
The groove is cut into the center of the lens edge for a balanced fit.
Yes, the width may vary slightly depending on the gauge of the nylon cord used by the frame manufacturer.
If the groove is too wide, the cord will be slack, allowing the lens to move and potentially fall out of the frame.
If your semi-rimless lenses "click" or move when you clean them, the groove width may not match the nylon cord thickness. This movement can lead to "optical decentration." Have an optician tighten the cord or replace it with a thicker gauge to secure the lens.
Optical Laboratory Association. Finishing Best Practices (ola-labs.org). 2023.
The Vision Council. Eyewear Maintenance and Care (thevisioncouncil.org). 2024.
ABDO. Spectacle Lens Edging (abdo.org.uk). 2024.
Review of Optometry. Troubleshooting Lens Movement (reviewofoptometry.com). 2024.