Although ordinary lenses can basically meet People's Daily eye use needs, but with the increasing number of nearsighted people, according to different use scenarios, lens manufacturers have designed functional lenses that are commonly used.
For example, anti-blue lenses for mobile phones and computers, discoloration lenses for outdoor sunlight in summer, night driving lenses for frequent night driving, and progressive lenses for specific people...
What is a progressive multifocal lens?
Literally, it can be known that it is a kind of lens composed of multiple focal points and different degrees.
Generally, there are four areas: far area, near area, progressive area, left and right deformation area (also called peripheral area or fuzzy area).
The lens has invisible imprint and dominant imprint ~
Progressive lenses are suitable for people
In actual work, the criteria for judging whether a person is suitable for wearing progressive lenses need to be determined according to the needs of customers. After determining whether the customers are suitable for the population, our staff should perform accurate optometry on them to ensure that they have a suitable prescription for glasses.
Indications for progressive lenses
1. It is difficult to see near, so reading glasses are needed, hoping to avoid the trouble caused by the replacement of glasses due to far-sighted people.
2. Wearers who are not satisfied with the appearance of bifocals or triocals.
3. People in their 40s and 50s who have just entered the "presbyopia" stage.
4. Look far and near people who swap frequently: teachers, speakers, administrators.
5. Public communicators (e.g., state leaders wear progressive multifocal lenses).
Contraindications of progressive lenses
1. Long time to see close personnel: such as computer too much, painters, drawing designers, architectural design drawings;
2. Special occupation: such as dentists, librarians, (because of working relations, usually use the top of the lens to see the closer) pilots, sailors (use the top of the lens to see the closer) or use the upper edge of the lens to see the target population, high mobility, exercise;
3. Patients with anisometropia: both eyes with anisometropia >2.00D, effective column degree >2.00D, especially axial asymmetry;
4.ADD more than 2.50D (" near use +2.50d ", indicating that the eyes have developed presbyopia, you need to increase the reading glasses of 250 degrees.) ;
5. Over 60 years of age (depending on health condition);
6. Those who often wear double light before (because of the wide near use area of double light and the narrow near use area of progressive mirror, there will be inadaptability);
7. Some patients with eye diseases (glaucoma, cataract), strabismus, degree is too high should not wear;
8. Motion sickness: refers to a combination of dizziness and dizziness caused by poor balance function in rapid autonomous or passive motion, such as motion sickness, seasickness, etc.; In addition, patients with hypertension and arteriosclerosis, when their disease is not effectively controlled, often appear due to insufficient cerebrovascular blood supply caused by dizziness, sometimes can also cause vasospasm, and headache;
9. People with difficulty in adapting to glasses;
The key to progressive lenses: Accurate optometry
Nearsightedness is shallow, and farsightedness is deep.
Due to the particularity of progressive multifocal lens compared with single-light lens, progressive multifocal lens should not only satisfy the good vision in the far light area, but also take into account the actual effect in the near light area to make the whole progressive lens comfortable to wear.
At this time, the "far light accuracy" should be based on the good use of near light, so the myopia luminosity of far light should not be "too deep", while the myopia luminosity of far light should not be "too shallow", otherwise the "too large" of ADD will cause the comfort of the lens to decline.
On the premise of ensuring that the far-light vision is clear and comfortable within the actual range of use, the far-light of the progressive lens should be shallow and the far-sight light should be deep and just deep.
Selection and adjustment of progressive lens frames
Progressive multi-focus is very important for selecting the right frame and adjusting. Specific attention should be paid to the following points:
Frame stability is good, in line with the customer's face shape, generally should not choose easy deformation of frameless frame, to ensure that the front curved curvature of the frame and the wearer's forehead curvature is consistent.
The frame must have a sufficient vertical height, which should be selected according to the type of lens selected. Otherwise, it is easy to cut the near part of the view when cutting the edge:
The medial area of the lens nose shall be sufficient to accommodate the gradient area; Ray-ban frame and other frames with large incline at the bottom of the inside of the nose near the field of vision is smaller than the general frame, so it is not suitable for gradual mirror.
The eye distance of the frame lens (the distance between the posterior vertex of the lens and the anterior vertex of the cornea, also called the vertex distance) should be as small as possible without touching the eyelashes.
Adjust the front Angle of the frame according to the facial features of the wearer (after the frame is fitted, the intersection Angle between the plane and the vertical plane of the mirror ring is generally 10-15 degrees, if the degree is too large, the front Angle can be adjusted to be larger), so as to match the frame with the face as far as possible, so as to help maintain enough gradual visual field.
Post time: Dec-05-2022