Optometrists spend years learning how to correct your vision, but that's no guarantee your eyeglasses — which can cost hundreds of dollars — will be made right.
Almost 30 states do not require a dispensing optician to get a license. One Texas optometrist joked that you could be flipping burgers Monday and fitting eyeglasses Friday.
In the optometry industry, there are precise quality specifications that each pair of eyeglasses has to meet and they are rated on a pass-fail system.
David Schechter, a reporter at ABC News' Fort Worth Texas affiliate WFAA, checked lenses from some of the biggest chain stores in the area and found that most of them failed.
Most patients don't realize their glasses may be causing problems, said one optometrist.
These include "visual stress to headaches to outright blurs in vision," said Texas optometrist David Frazee.
WFAA bought six pairs of glasses from national retail chains and then had them inspected by three optometrists.
They found a variety of defects, and of the six pairs purchased, the optometrists failed four.
In another test, Frazee wrote a sample bifocal prescription and WFAA took the prescription to Target, Wal-Mart, Costco and LensCrafters to get it filled.
The one store to meet accepted industry specifications was also one of the cheapest — Costco.
"Every part of the prescription was nailed 100 percent," Frazee said of the Costco glasses.
The three optometrists agreed the glasses from Wal-Mart were well-made, but failed them anyway. The glasses were made with a different material than what the doctor had ordered.
The Target glasses had more significant technical problems. In several key measurements, the power of the lens failed to meet industry standards. And the frame should not have been sold to us in the first place.
"The segment height, or bifocal height, was way too high," Frazee said.
The LensCrafters glasses — the most expensive of the four — were called the worst of the bunch by two of the three optometrists.
"This was an absolute failure," Frazee said.
Frazee said that according to industry standards, the lens power in one eye was out-of-tolerance. The bifocals lines were crooked and too small, he added.
"The individual wearing these glasses would have been raising their head like this all the time," Frazee said.
To be sure this wasn't an isolated incident with one LensCrafters, WFAA went to two more LensCrafters to fill the same prescription.
One pair passed, but the other failed for not meeting industry standards for lens power. And all three optometrists observed the bifocal lines were crooked and could be hard on a patient's eyes.
Of the three pairs of glasses purchased from LensCrafters, two failed quality testing.
And it turns out that Target contracts with the same company that owns LensCrafters to make its glasses and those also failed.
LensCrafters inspected the four pairs of glasses, and while they disagreed with some of WFAA's findings, they still failed two of four pairs.
The company said in a statement, "We stands behind our products and services and encourage our customers to allow us to fix any errors that do occur."
Frazee believes poorly trained opticians are to blame for most of the problems.
Opticians fit you for glasses and check to make sure they were made correctly — they are not the same as optometrists.
In more than 20 states, opticians are required to get two to four years of on-the-job training and be licensed by the state.
But in nearly 30 states, that means there are no licensing requirements.
In response to the WFAA piece, LensCrafters said it could have corrected some of the problems if someone had sat for a proper fitting.
Wal-Mart issued this statement: "We pride ourselves in the accurate fulfillment of prescriptions, and if we have fallen short, we will do anything we can to put things right."