Glasses frame is an important part of glasses, which mainly plays the role of supporting glasses. Glasses frame with beautiful appearance can also play a beautiful role. Materials mainly include metal, plastic or resin, natural materials, etc. By style, it can be divided into full frame, half frame, frameless and other types.
The optical and metrological technical indicators of spectacle frames are very important for consumers' comfort in wearing glasses. The selection of spectacle frames must meet the optical and metrological requirements:
(1). After wearing glasses, ensure that the distance from the lens to the eyeball is about 10mm.
(2). The geometric center size of the spectacle frame should preferably be close to the distance between the pupils of both eyes (preferably less than 4 to 10 mm).
Considering that the blank of the lens must be moved to the center and cut before it can be installed on the spectacle frame and placed in front of you, the position of the pupil should be facing the geometric center of the spectacle frame, preferably less than 4 ~ 10mm. If the lens shift center is very large, it may cause prism and other effects, affecting the comfort of wearing glasses.
(3). The included angle between the front mirror of glasses and the vertical line of the wearer's face is about 4 ° ~ 18 °.
The size of the angle is related to the field of view. Generally speaking, the upper part of the frame cannot touch the eyebrows and the lower part cannot touch the face. If the frame cannot reach the required forward tilt angle, it is recommended to find a professional to adjust the nasal bracket or change a pair of frame.
(4). The width of spectacle nose frame is moderate.
When consumers choose the spectacle frame, they can check it by themselves through the following methods: keep the head vertical and look forward, and the spectacle frame can maintain a satisfactory position without any clamping of the spectacle legs.
If the nose bridge frame is too narrow, not only will the lens be too high in front of you, but also the contact part between the nose bridge frame and the nose will be uncomfortable, and even cause temporary depression of the skin tissue of the nose; If the nose bridge frame is too wide, the lens will fall too low, and the lens leg cannot keep the spectacle frame in its normal position for a long time.
(5). The length of glasses legs is moderate.
In principle, the curved part of the mirror leg should be just above the ear fold, but the pressure on the ear fold should be avoided.
If the leg length is not enough, the glasses will tilt upward, and the tail of the glasses frame will press into the back of the ear, making the wearer feel uncomfortable; If the length of the lens leg is too long, when the head tilts, the tail of the glasses frame will contact the back of the ear, and the glasses will fall down by themselves.
If the angle of the front frame is too long, the length of the front frame should be considered. If you don't wear the glasses for a long time, you should pay attention to the length of the front frame.
(6). The deeper the negative diopter (commonly known as myopia), the smaller the lens circle is better.
(7). Generally speaking, those with large astigmatism should not use a circular frame.
(8). Considering the role of visual aberration and prism, ordinary consumers had better not choose the frame with too large radian.
(9). For children, you can choose a transparent mirror frame without nose pad. If the nose pad is too high, it will show the characteristics of collapsing nose bridge.
In addition, it is worth reminding that if consumers often wear glasses with metal frames and suddenly replace them with plastic frames, or vice versa, they will feel uncomfortable just wearing them. This is because metal frames generally have nose supports. With nose supports, you can adjust the vertical distance between the lens and the eyeball. Often wearing metal frames will be more suitable for the distance of metal frames, while plastic frame frames have no nose supports, so the distance cannot be adjusted, and you will feel uncomfortable when you just wear them. Generally, about a week is the adaptation period. After the adaptation period, the discomfort will gradually disappear or significantly reduce. If it still does not reduce, it is recommended to find a professional for consultation or reuse the original frame.