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Phone: (US) (800) 410-1618  (INT) +1 (267) 203-8665   Fax: 1 (800) 468-9301

Phone:   (US) (800) 410-1618     (INT) +1 (267) 203-8665
Fax:   1 (800) 468-9301

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  • Learning Center
    • Why a Learning Center?
    • Principles of Vision
      • A Tour of Your Vision
      • Central vs. Peripheral Vision
      • What is a Refraction?
    • Opticianry Basics
      • How do Glasses Work?
      • How Do Bifocals Work?
      • Basics of Prism
    • Vision Conditions & Rehabilitation
      • Low Vision & Field Loss
        • Homonymous Hemianopia
      • Neuro-Visual Conditions
        • Migraines
        • Concussions And Other TBIs
        • Photosensitive Epilepsy
      • Binocular Vision Dysfunction 
        • Aniseikonia
        • Convergence Insufficiency
    • The Peli Lens™
      • The Peli Lens for Driving
      • Resources for Doctors
      • Resources for Patients
    • Ask Chadwick
  • Optical Lab
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      • Avulux Migraine Glasses
    • Tint Library
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    • SHAW™ Lenses
    • Aire-O-Lite Lens Blanks
    • Low Vision Devices
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    • Diagnostic & Assessment Kits
      • Magna-5 Evaluation Kit
      • Peli Evaluation Kit
      • Size Lens Kit
      • Tint Selection Kit
    • Tints & Filters
      • Tints & the Tinting Process 
  • Resources
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      • Order Form and Business Reply Card
      • Pricing Guide
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Opticianry Basics

Sometimes it's best to start with the basics. Call it a refresher, or maybe you're new to opticianry altogether. Either way, this section of our site focuses on fundamental concepts like how glasses, bifocals and prism work.

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How Eyeglasses Work

How Eyeglasses Work

Bifocals3_ChadwickOptical
How bifocals work

How Bifocals Work

prism-angles-face-ChadwickOptical
Basics of Prism

Basics of Prism

Need something specific?
Give us a shout!


596 Main St Suite D
Schwenksville, PA 19473
Phone (US): 800-410-1618
Phone (INT): 267-203-8665
Fax: 800-468-9301

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