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Near PD (Pupillary Distance) is the horizontal measurement between the center of one pupil and the center of the other pupil when the wearer is looking at a close object (typically 16 inches away). This measurement accounts for convergence, the natural inward turning of the eyes when focusing up close.
read more about near pd for eyeglasses ...The near PD measurement is needed to horizontally position the optical center of the lens for close-up tasks. Since the eyes turn inward when reading, the near PD is smaller than the distance PD. Using the wrong (distance) PD for reading glasses would cause eye strain and visual discomfort.
Near PD is measured by an optician while the patient focuses on an object held at a typical reading distance. The optician uses a ruler or digital device to find the distance between the pupils while the eyes are in their converged position.
The near PD is usually 2 to 4 millimeters smaller than the distance PD. This difference accounts for the horizontal distance the eyes shift inward (converge) when focusing from far away to near.
Accurate near PD is important for your backup reading glasses. Since contact lenses float and adjust, they provide seamless near vision. Your backup reading glasses must have the correct near PD to provide stable, comfortable close-up vision when you switch from contacts.
No, driving glasses use the Distance PD measurement because the wearer focuses on objects far away.
Yes, near PD is used for any lens that is primarily designed for close-up work, including bifocals and progressives.
Yes, the near PD can be calculated by subtracting 2 to 4 mm from the distance PD, but it is always best to measure it directly for accuracy.
If you experience double vision only when reading, your Near PD may be misaligned. When eyes converge to read, they require a specific optical center. If this is off by even 2mm, it can trigger binocular vision strain that mimics "lazy eye" symptoms.
Mayo Clinic. Near Vision Loss (mayoclinic.org). 2024.
Review of Optometry. Managing Binocular Vision (reviewofoptometry.com). 2023.
ABDO. Calculating Near PD and Inset (abdo.org.uk). 2024.
Cleveland Clinic. Convergence Insufficiency (clevelandclinic.org). 2024.