Let's talk about the adjustment method of spectacle frames

Let's talk about the adjustment method of spectacle frames

Many optometrists have problems adjusting their spectacle frames almost every day. In the eyes of the customer, it is very simple to use the tool to get it right, and it is OK, but in fact, the technology covered in it is extremely important. It is no exaggeration to say that a good pair of glasses is just as important as optometry and prescription, and in a sense, even more so. If the customer's refraction parameters are normal and the glasses are accurately fitted, but the wearing is not comfortable, then for the customer, the customized glasses lose the meaning of improving the visual function. Therefore, school glasses are very critical, and many problems can be solved by school glasses. In the traditional business model, optical stores prescribe their own lenses (traditional lenses) and calibrate glasses. In the new lens processing mode, the frame is calibrated before the lens is assembled, and the lens needs to be assembled after freeform processing, such as sunglasses and high-curved lenses. Lens Differences Different lenses have different calibration methods. Therefore, differentiating the lenses is the first step. Spherical lenses are calibrated differently from aspherical lenses, and the calibration of single vision lenses and multifocal lenses is also very different. Spherical single vision is a curved design of the lens, which belongs to the most traditional lens design. Aspherical, anti-fatigue, multifocal, progressive multifocal, etc. are a different story. The surface of these lenses is not composed of a single curved surface, but is formed by two or more curved surfaces with different outer and inner surfaces. Common problems of frame adjustment 1. Problems caused by lens angle distance Lens angle distance: refers to the distance between the vertex of the inner surface of the lens and the anterior vertex of the cornea, the lens angle distance is also called: apex distance, mirror eye distance, VD distance, lens angle distance is generally 12mm. The recommended distance is 10mm~15mm, and the correct angle distance is very important, which is the basis for correct optical correction. Regardless of which type of lens is calibrated, we recommend that it be fitted to the face as much as possible, so that the eyelashes do not reach the lenses. This is because the closer the lenses are to the face, the smaller the aberrations will be, and of course, the degree of myopia may also become deeper. But in terms of the authenticity of the object image, the closer the lens is to the face, the better. If the object is too large or too small, if the astigmatism is distorted, or if you feel color on the edges of the object when you see an object, you should adjust the lens as close to the face as possible. The distance between the left and right eyes should also be the same. If there is a deviation, it will lead to different aberrations, and there is a possibility of discomfort in the fusion of the image. 2. Problems caused by inclination angle Inclination angle: refers to the angle between the plane line and the vertical line of the lens, generally between 8 掳 ~ 15 掳, and is reasonably inclined according to the face shape of the eyes and nose, which is the basis for comfortable wearing and optimal optical correction. Yellow people are generally between 8掳~10掳, and Caucasian people have deep eye sockets, generally between 12掳~15 degrees. Each pair of glasses must have a certain angle of inclination, and the size of the angle of inclination depends on the actual situation of the wearer's eyes. If the eye protrudes forward, the tilt angle is smaller, and if the eye is deep, the tilt angle should be slightly larger. Different lenses require different angles of inclination. Bifocal and progressive lenses typically have a larger angle of inclination, while aspherical lenses have a slightly smaller angle of inclination. For those with sensitive skin, they should try to avoid excessive tilt angles to avoid the frame sticking to the face and causing discomfort. The lenses are fogged for no reason, partly due to improper handling of the tilt angle. 3. Problems caused by mirror bending Mirror bending: refers to the angle between the plane lines of the left and right lenses, the mirror bend is generally between 170 掳 ~ 180 掳, and it is reasonably adjusted according to the face shape of the eyes and nose, which is the basis for aesthetic wear and the best optical correction. Specular bending is one of the most overlooked problems in the tuning process. When the wearer looks sideways, too small or too large a mirror curve will cause the mirror distance of the left and right eyes to be different, the power is different, and the prism effect is also different. The mirror curve is not as big as possible, generally 170掳~175掳 is better, if you do diopter correction on sunglasses, it is recommended to do freeform lenses. If the specular bend is too large, there will be a different prism effect when looking straight and sideways, and when looking sideways, monocular astigmatism will occur. Precise mirror curvature is especially important when using progressive lenses, which reduces the blurring of vision from left to right of the eyes. When wearing single-vision aspherical lenses, it is recommended to enlarge the interpupillary distance by 2mm to reduce discomfort, taking into account the curvature of the mirror curve. 4. Problems caused by pupil height If the pupil height is incorrect, it will produce a pronounced prism effect. Inverse dilated pupil height has little to do with it, but the oblique axis is important because the oblique axis produces different magnifications and can be improved with the pupil height. If it is the oblique dispersion of the figure-of-eight axis, the distal vision is deformed, and the near vision is normal, the pupil height can be lowered, if the distal vision is normal, and the near vision is deformed, the pupil height can be lowered, and if it is a V-shaped axis, the same is true. If you are anisometropic, you must divide the left and right sides to make the quasi-pupil height to ensure the comfort of wearing. If it is a single-vision aspherical lens, the pupil height should be appropriately moved up by 1~2mm from the horizontal line according to the frame height (see the frame structure for details) The double eye pupil height is generally: (frame height梅2)- 1~2mm. It's best to measure it in practice. Progressive pupil height is generally 0.618 脳 frame height. It's best to measure it in practice. If the visual distance time is longer, it will drop by 1mm, and if the near vision time is shorter, it will move up by 1mm. There are some cases of unequal height. 5. Interpupillary distance problem: If the inverse dilated interpupillary distance is incorrect, it will produce a noticeable prismatic effect. Single-pass dilated interpupillary distance has little effect, but the oblique axis is very important, because the oblique axis produces different magnification problems that can be improved by interpupillary distance. If it is oblique and distorted in the figure-of-eight axis, the interpupillary distance is reduced; If it is a V-shaped axis, the visual proximity is deformed, and the interpupillary distance is dilated.If there is an anisomeness in refractive power, be sure to test the interpupillary distance of the left and right eyes separately and assign it. 6. Wearing discomfort caused by different face shapes of customers As the saying goes: a thousand people have a thousand faces. Each customer's face shape is different, so frame adjustment due to discomfort is the most complicated. Most people have a slight asymmetry between the left and right sides of their faces, but some customers have a large difference between the left and right faces, which can cause one side of the frame to touch the skin and the other side to hang high. In this case, the frame needs to be adjusted. First, observe that the bridge of the nose is vertical, and if you notice a deviation from the left or right, you need to adjust the nose pad. When we find that the two eyes of the person wearing the glasses are not on the same level, please adjust the center of light to align with the pupil, which can reduce the effect of the prism. Customers with squint vision habits are not suitable for progressive lenses; Customers who need head position compensation are not suitable for aspherical lenses. 7. Problems caused by stress If the customer has the following problems, it is likely to be caused by stress: Everything is normal when looking at the customer, but when looking sideways, it feels that the vision is not clear, or the object is clear but feels dizzy. If you can't wear glasses for a long time, it is easy to get tired of sight. When you look at it, there is an irregular glare, but you can't explain the occurrence of this phenomenon. The stress factor should not be ignored, it will directly lead to optical defects, such as astigmatism, chaotic polarization, etc., and affect the visual effect.