As we discussed last month, there are many steps that go into taking the refraction measurements during the eye exam. That is actually only the first step in the process of getting your new favorite pair of glasses. Today I will discuss the many steps that go into translating your new prescription into a pair of finalized glasses that are ready to wear. The entire process is more complicated than you may realize, and there are many steps in the process that if done incorrectly can cause the final product to not be perfect. I consulted with our head optician Bryan to explain the many steps in this process, and how to ensure some of the most common glasses manufacturing mistakes can be avoided to ensure a perfect final product.
It’s all about the frame selection
I think that the most important part of the entire glasses making process that will go a long way to ensuring a good result is proper frame selection. There are countless frame options, but not all of these will provide a good looking final product. Certain frame styles will work much better for high prescriptions, and it can even vary depending on if a prescription corrects for myopia or hyperopia. The size of the frame, the materials it is made of and the method of mounting the lenses will all play a part in how to the final product appears. In general for myopic prescriptions, a larger frame will lead to lenses that are thicker and heavier. Generally a smaller and rounder frame is a good option for these types of prescriptions. A high hyperopic prescription will also cause thicker and heavier lenses, but the frame shape is not as critical as the overall frame size in producing a good looking final product. For bifocal or progressive lens prescriptions, the frame needs to be large enough to be able to move the eyes into the reading portion of the lens, but not too large that the reading portion is out of view. Once a proper frame is selected, the rest of the manufacturing process will be much easier.
After the frame is selected, it must be adjusted to properly fit the patient’s face. This allows all the necessary measurements to be much more accurate. Several measurements must next be taken while wearing the frame to ensure that the final lens is centered on the eye, and this ensures the patient is looking through the correct portion of the lens. The most common measurements taken are the pupillary distance, and the optical center. These measurements allow for proper horizontal and vertical alignment of the lenses within the frame. The exact prescription is only correct in one portion of the lens, and this central portion must be properly aligned with the pupil. If the alignment is off, depending on the prescription strength, it can cause distortion and blur, and a higher prescription will cause more distortion and blur if these measurements are incorrect. Specifically for progressive lenses, several other measurements can be taken to ensure proper lens alignment. These include vertex distance (the distance from the lens to the eye), pantoscopic tilt (the amount of lens tilt around the horizontal axis) and lens wrap (the amount of lens tilt around the vertical axis). By ensuring all of these measurements are accurate, it will allow the next steps of the process to completed with much more precision.
Let the machines do their thing!
The next step in the glasses making process involves actually cutting the lens down to size and fitting it into the frame. A standard size lens is a 65mm circle when ordered from the manufacturer with the prescription. This lens must first be inspected for any defects and to ensure the prescriptions is accurate. The previously mentioned measurements must then be used to mount the lens on what is called a blocker. This ensures the lens stays in the correct orientation when it is placed in the lens edger and cut down to size. The blocked and mounted lens is then placed in the edger where a series of files and grinding wheels reshapes the lens to the proper size for the desired frame. At this point in the process the lens edges are cut in the proper shape to fit into the frame groove. Drill holes can also sometimes be used to mount the frame if needed. Depending on the frame and the desired final look, the exposed edges can also be polished. Once the lenses are both cut down to the appropriate size, the lenses are mounted into the frame. The final inspection of the lens then involves marking up the lens based on the measurements to ensure the lens center is in the appropriate location.
Custom fit to you!
When you pick up your new glasses, it is important to take the time to do it in person so any final adjustments can be made. After this entire process, if the frame is slipping off your nose it does not matter how the lenses were made if you can’t actually use them! Any necessary final adjustments are only possible if the frame is fit in person, and we always encourage patients to pick up their own final glasses for this reason if possible. Once the frame has been worn for a few days, it is also important to note anything that needs to be adjusted further, so we can address it quickly.
From the exam room until the final glasses are on your face, we try to perfect the entire process so the end result is exactly what you want. We pride ourselves on being perfectionists, and it is very important to all of us involved in the process to get it right correctly the first time. Please let us show you why we think we are the best in town, and why we think you will love your new Optique eyewear.
Also…come see the folks in the optical lab making glasses sometime, because the process is honestly pretty cool!