How to Troubleshoot a Progressive Lens

Progressive lenses, also known as no-line bifocals, are one of many options for people who need bifocals. The manufacturing process for progressive lenses involves extremely complex surfacing procedures that are guided by a computer. They are surfaced based on measurements that are accurate to the millimeter, and when fitted properly with the finished lens matching the order exactly, they provide excellent vision. However, if any parameter is incorrect by as little as one millimeter, they can be quite difficult to see through. There is a process to work through when troubleshooting any problems with a progressive lens.

Things You'll Need

• Black dry erase marker
• Millimeter ruler
• Progressive lens identifier

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Instructions

• 1

  Visually inspect the physical fit of the glasses frame on the subject's face. Ensure that the frame is not tilted to one side or the other. Check the nose pads to see that they sit flat on the subject's nose and are level with one another. Look behind the subject's ears to make sure the ear pieces are level with one another. Add pantoscopic tilt by bending the frame where the ear piece and eye piece join. Do this to both sides equally. Add wrap, or face form tilt, to the frame by bending it inward at the bridge between the lenses. If adjusting the frame properly does not help, check the distance between the pupils.

• 2

  Hold the lens up to a light source in order to visualize its engravings. These marks are used to help verify the distance between the pupils in the lens. Find the circle or diamond shapes on the outside and inside of both lenses. Use the dry erase marker to place a dot in the center of each circle or diamond shape. Find the symbols on the lens below the dry erase dots. Using the progressive lens identifier listed below as a reference, find the page that has the subject's lens diagram. Align the dry erase dots with the diamond or circle shapes on the lens diagram. Place another dry erase mark over the plus as it shows through the subject's lens. Do this for both lenses. Place the glasses on the subjects face. See if the dots align with their pupils.

• 3

  If the pupil marks do not line up, take the glasses back to where they were purchased. They will likely need to be reordered. If the frame is in perfect adjustment and the pupil marks line up, yet the subject is unable to see, the subject needs to see their eye doctor to find a solution.