How to judge whether the quality of glasses is qualified?
It is not difficult for users who need to wear new eyeglasses online to wear a pair of qualified glasses, but how to judge whether their glasses are qualified? Just pay attention to the following three aspects:
1. Are the parameters of the optometry sheet correct and complete?
First of all, you should go to the ophthalmology department of a professional eye hospital or general hospital with a specific scale for optometry. The optometrist will write out a prescription (handwritten or format) suitable for your prescription eyewear according to your particular situation. The contents include the parameters of the spectacles, such as
√ spherical lens power (myopia power)
√ cylinder lens (astigmatism power)
√ cylindrical lens axis position (astigmatism axis position)
√ binocular pupillary distance (the sum of left and single right eye pupillary distances), etc. If it is equipped with a progressive multifocal lens, the degree of "add light ADD" must be provided.
2. Is the selection of frames and lenses correct?
How to know if your glasses prescription is wrong? For the size of the frame, you can check the size of the original wearing frame. Choose the one close to the "frame width" size, or directly measure the total front width of the original eyeglasses frame, and select the one close to the "front total width" size. When choosing a frame, the most important thing is to consider the consistency of the head width and the frame size, followed by beauty.
Be careful when trying on new eyeglasses at home.
√Horizontal position: the horizontal position of the pupil in the spectacle frame, which should be located inside the geometric center of the spectacle frame.
√ Vertical position: The edge of the lower eyelid should be located below the vertical center of the frame.
Disadvantages of users who choose too large frames:
√Increase weight and cause discomfort;
√ The lens center shifts too much, which affects the quality;
√ Form a reflection image, causing a visual disturbance;
√Edge distortion affects the appearance.
Children are best to choose plastic frames. The metal frame has larger nose pads, and the weight is concentrated on the nasal bones, which affects the development of the nasal bones. Children's frames should pay particular attention to the consistency of PD (interpupillary distance) and FPD (geometric center distance of the frame) and pay attention to timely replacement of the eyeglasses frame according to the growth and development.
The choice of the refractive index of the lens needs to be based on your actual power. The refractive index is usually divided into 1.56, 1.60, 1.67, and 1.74. The larger the value, the higher the refractive index. The conventional 1.56 is called ordinary spectacle lens, suitable for people with myopia below 300 degrees. Businesses of 1.60 and above will call them ultra-thin lenses, ideal for 300-500 degree myopia. With the same refractive index and interpupillary distance, everyone knows that the higher the myopia degree, the higher the thickness of the spectacle lens and the heavier the weight of the entire spectacle. The selection of lenses mainly considers safe products, light, high light transmittance, can absorb harmful rays to the eyes, wear-resistant, and have good chemical stability and practical effects.
3. Does the processing and verification of the glasses meet the national standard?
An optometry prescription is just like a doctor dispenses medication to a patient. The quality of the lens preparation is directly related to whether the prescription glasses meet the requirements on the optometry prescription, just like whether the medicine prescribed by the medications meets the requirements prescribed by the doctor. Generally speaking, the preparation of lenses includes multiple processes such as blank selection, rough grinding, fine grinding, polishing, positioning, cutting, and mounting. Each process is related to the quality of the lens and its assembly. Under normal circumstances, the merchant only undertakes the post-processes such as positioning, cutting and assembly, polishing, and installation. At the same time, the processing and production of the lens are completed by the lens manufacturer. The merchant should pass 100% inspection before handing over the finished lens to the customer. All indicators must meet the national standards, especially opticians, who should strictly control the optical parameters. Finally, a targeted adjustment should be made according to the consumer's face shape and visual habits to ensure that the distance between the glasses and the eyeball and the inclination angle to the face plane meet the requirements. We know what qualified prescription frames are, and how should we choose suitable prescription eyewear? It requires close cooperation between hospitals, optical shops, and individual consumers. As far as consumers are concerned:
√Selecting the right lenses.
√Choosing the right frames.
√Carefully cooperating with optometry and calibration are also indispensable.