How are eyeglasses made and fitted?
This first section is about creating eyeglass lenses. Here’s an overview of the process:
Prescription Assessment: The first step is to obtain a prescription for eyeglasses from an eye care professional, which includes the necessary corrective power for each eye (measured in diopters) and any other relevant information, such as the type of correction needed (near-sightedness, far-sightedness, astigmatism, etc.).
Pupil Distance Measurement: The optician will measure the distance between your pupils, called the pupillary distance (PD). This measurement is essential to ensure that the lenses are centered correctly within the frames, allowing you to see through the optical centers of the lenses.
Lens Selection: Based on the prescription and the patient’s needs, the optician will help choose the appropriate lens material and design. Common materials include glass, regular plastic (CR-39), polycarbonate, and high-index materials. Each material has its own unique properties and advantages. The thinner and lighter lenses are used for higher prescriptions.
Lens Surfacing: Once the lens material is selected, the prescription information is sent to a lab where the lens surfacing process begins. This involves cutting the lenses to the required shape and size to fit the chosen frame. Automated computer-controlled machines are used to achieve high precision during this process.
Lens Edging: If the frame chosen requires lenses with a specific shape (e.g., rimless or semi-rimless frames), the lenses may undergo additional edging or beveling to fit precisely into the frames.
Lens Finishing: After surfacing and edging, the lenses may go through additional processes, such as polishing to improve clarity and applying special coatings like anti-reflective coating, scratch-resistant coating, or UV protection.
Quality Control: Throughout the manufacturing process, quality control checks are performed to ensure that the lenses meet the prescribed parameters and are free from defects.
Lens Fitting: Once the lenses are ready, they are fitted into the chosen eyeglass frame.
Final Inspection: Before delivering the eyeglasses to the customer, a final inspection is conducted to verify the accuracy of the prescription and ensure the lenses meet all quality standards.
Ensuring that eyeglasses fit properly is crucial for providing optimal vision correction and ensuring the wearer’s comfort. Opticians follow a systematic approach to achieve the best fit for each individual. Here’s how they do it:
Bridge Fit: This is a check of the fit of the frame’s bridge, which is the part that rests on the wearer’s nose. It should sit comfortably and evenly without putting too much pressure on the nose. There should be no sliding down or slipping of the glasses.
Temple Length Adjustment: The temples (arms) of the frame should be adjusted to fit snugly around the ears, providing a secure fit without causing discomfort. Opticians can adjust the temple length and curvature to achieve the desired fit.
Frame Alignment: Proper frame alignment is essential for ensuring that the lenses sit correctly in front of the eyes. The optician checks that the frames are not crooked or misaligned and that they sit level on the wearer’s face.
Vertical Alignment: The optician checks the vertical alignment of the lenses to ensure they are positioned correctly in front of the eyes. Proper vertical alignment is especially crucial for individuals with astigmatism or progressive lenses.
Nose Pad Adjustment: If the frame has nose pads, the optician adjusts them to ensure an even distribution of weight on the nose and to prevent the glasses from sliding down.
Secure Fit: The optician ensures that the glasses fit securely on the face, even during head movements, bending, or other activities. This helps prevent the glasses from slipping or falling off accidentally.
Comfort and Balance: The optician considers the comfort and balance of the eyeglasses on the wearer’s face. The glasses should not cause any pressure points, discomfort, or headaches during extended wear.
Vision Testing: Finally, the optician checks the wearer’s vision with the new glasses to verify that the prescription is providing the intended correction and that there are no issues with the lens placement that would affect visual clarity.
Advancements in technology have made it possible to create customized lenses, especially for those with complex prescriptions or unique vision needs. Digital surfacing and free-form technology allow for personalized lenses that can optimize the visual experience based on the individual’s prescription, frame choice, and lifestyle requirements.