: If you're prone to losing small items, Walmart offers a multi-pack of straight-edge white rulers. Ezyaid PD Ruler
: Available on eBay, this version features a nose bridge design and includes eye care tips for children. pupillary distance ruler buy
Measuring your PD is the final step in translating a paper prescription into a functional pair of glasses. If the measurement is off, the "optical center" of the lenses won't align with your eyes, leading to headaches, blurred vision, or eye strain. What to Look for in a PD Ruler : If you're prone to losing small items,
When buying a ruler, look for features that minimize human error: If the measurement is off, the "optical center"
You can find PD rulers for as little as $1 to $18, depending on the material and included guides. PD Ruler with Instruction Manual