Some short knowledge of prescription glasses
Prescription glasses need to be worn for life, and it pays to learn more.
1. Myopic lenses are concave lenses, thin in the middle (not thinner than 1.0 mm) and thick at the edges; the higher the degree, the thicker the edge of the lens, the more the object shrinks, the greater the thickness of the center the thicker the lens (see link below). Nearsighted lenses move the focal point of the nearsighted eye back and fall on the retina to get a clear image. Farsighted/presbyopic lenses are convex lenses, thicker in the middle and thinner at the edges; the higher the degree, the thicker the middle. Farsighted lenses move the focus forward, dropping the focal point of the farsighted eye on the retina to get a clear image; the smaller the diameter of the farsighted lens blank, the thinner it is. Seeing objects becomes larger.
2. resin lenses are light, not easy to break, not wear-resistant, and can be made with rimless glasses, half-frame glasses, and full-frame glasses. The glass piece is heavy, easy to break, and wear-resistant; under normal circumstances, it can only do full-frame glasses, half-frame glasses frame very few people choose because bad slotting will not be durable.
3. the principle of myopia optometry is the lowest degree of the clearest state. Farsightedness is the highest degree of the clearest state. The specific situation has to be analyzed. Use the red and green test icons to determine whether the degree is a full correction. Myopia is under correction, red font is clear. Myopia overcorrection is clear in green. Farsightedness is the opposite. Always be right before left, whether it is optometry or processing or wearing invisible or measuring data, so as to maximize the guarantee that will not be wrong.
4. farsighted/presbyopic or flat because the edge is too thin, not suitable for half-frame glasses, because too thin, it is easy to collapse the edge, is not durable. (Positive degree high, the amount of shift center is also okay, you can choose half-frame because the edge is not thin). Rimless is even less recommended. Customers like half-frame, then you can choose not easy to break the PC lenses to match can also be.
5. The less light there is, the larger the pupil and the worse the vision. So the night vision will become worse.
6. poor quality sunglasses without UV protection are very harmful to the eyes; the lenses have color blocking the light, the pupils dilate, and UV rays drive straight in.
7. resin lens wear-resistant or not mainly depends on the lens film layer, and the material does not have much to do with it. Because the membrane layer is in direct contact with external forces, the membrane layer is bad, and the lens can not be used; the material steel is also useless.
8. For the human eye to see close, the need to use the adjustment force; the closer the distance, the more adjustment, and the longer, the more tired. So look as close as possible to pull away, and do not use your eyes continuously for a long time. -3.00 degrees theoretically can only be seen clearly within 33 cm, and it is recommended that people above -3.00 look close to also wear glasses, do not wear will be close to see, regulation and collection of roles lead to more easily fatigue, and then increase the degree. A summary: “When you can’t see clearly, you should wear glasses” this sentence is suitable for all myopic people.
9. The actual price of eyeglasses minus the brand premium is the cost of materials and labor, so most cheap glasses are premium and high quality.