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The as-worn position refers to the exact way the finished spectacle frame sits on the wearer's face, not just how it looks on the dispensing table. This fitting considers the frame's tilt, wrap, and vertex distance when measuring for lens optimization.
read more about as worn position in eyewear fitting ...The as-worn position is necessary for fitting modern, digitally surfaced lenses. These lenses are so precise that they must be calculated based on the final position of the frame on the face. If the calculation ignores the tilt and wrap, distortion can occur.
Three measurements define the as-worn position. Pantoscopic tilt is the angle of the frame bottom to the face. Face-form wrap is the horizontal curve of the frame around the face. Vertex distance is the distance from the back of the lens to the front of the cornea.
If the frame has a high face-form wrap (like sports glasses), standard lens calculations can cause peripheral blurriness. The as-worn position measurement adjusts the lens prescription to compensate for the curve, making sure peripheral vision is clear.
The precise calculation of the as-worn position makes your backup glasses the best they can be. This digital precision ensures that when you switch from your contacts to glasses, you experience perfect, distortion-free vision across the entire lens surface.
It is primarily needed for modern, digitally surfaced lenses, especially progressives, which require the highest degree of accuracy.
Most standard frames have a slight pantoscopic tilt (the bottom of the frame is closer to the face than the top) for better visual performance.
Yes, opticians can adjust the temples and nose pads to change the tilt and vertex distance to optimize the fit.
Position-of-wear (POW) measurements are critical for high-wrap or high-tilt frames. If your prescription is correct but vision is blurry in a sporty frame, the "as-worn" calculation was likely missed. Your optician should measure the tilt and wrap to compensate the lens power.
AOA. Proper Eyeglass Fitting (aoa.org). 2024.
Review of Optometry. Digital Dispensing (reviewofoptometry.com). 2023.
ABDO. Fitting and Adjusting Frames (abdo.org.uk). 2024.
All About Vision. Advanced Lens Customization (allaboutvision.com). 2024.