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Nylor groove depth is the precise measurement of how deep the groove is cut into the edge of a spectacle lens. This groove holds the nylon cord (nylor) used in semi-rimless frames to secure the lens in place where the frame rim is missing.
read more about nylor groove depth in eyeglass lenses ...The main function is to ensure the lens retention and stability. If the groove is too shallow, the nylor cord can slip out, causing the lens to fall. If the groove is too deep, the cord will create too much stress on the lens edge, potentially leading to stress cracks.
Groove depth is measured by the lab technician using specialized tools, often a digital caliper. The depth must be precisely matched to the thickness of the nylor cord being used by the frame manufacturer, ensuring a secure but low-stress fit.
Depth refers to how far into the lens edge the groove is cut, which controls stability. Width refers to the narrowness of the groove, which controls how tightly the nylor cord is held laterally.
Proper groove depth is important for frame integrity. The correct depth distributes the tension from the nylor cord evenly across the lens circumference, preventing the lens from rotating or vibrating during movement, which is important for maintaining stable vision.
No, the groove is cut by an automated edger machine to ensure precise and uniform depth.
No, glass lenses are too brittle and would shatter when the groove is cut. It is only performed on plastic or polycarbonate lenses.
The cord is typically a thin, durable, transparent nylon filament.
Semi-rimless ("Nylor") frames depend on a perfectly cut groove. If you see a crack running along the edge of your lens inside the groove, the lens is compromised. Replace the lens immediately to avoid shard injuries; your optician can verify if the tension was set too high.
Review of Optometry. Fitting Semi-Rimless Eyewear (reviewofoptometry.com). 2024.
The Vision Council. Lens Material Integrity (thevisioncouncil.org). 2024.
ABDO. Glazing for Nylon Cord Frames (abdo.org.uk). 2024.
AAO. Eye Safety and Lens Breakage (aao.org). 2024.