A good reading glasses is to meet the optical requirements, with price tag, and wear comfortable appropriate.It mainly reflects the following aspects:
1. The film shape must be relatively wide. Due to the gathering effect of presbyopia when it is close to the lens, plus the habit of reading and writing, the visual axis of monocular eye should move down and 2.5mm inward when it is far from the lens (head-up).When looking at head-up, the pupil is generally above or below the middle line of the tablet, so that the reading glasses have enough field of vision, the tablet should meet the requirement of height above or below 30mm, not the smaller the tablet is the better.The upper and lower 25mm of the narrow tablet is generally portable, temporary supplement to the use of vision.
2. The front of the glasses should be wide, but the OCD (horizontal distance from the optical center) should be small.Because reading glasses users are above middle age, face plump, presbyopic glasses level 10 mm size is generally optical frames, but nearly with distance is smaller than far with distance of 5 mm, so the OCD value women generally should be in 58-61 - mm, the male should be around 61-64 - mm, to satisfy the two requirements at the same time, the larger the diameter of the lens are used, and should have greater light heart when production shift.
3. Reading glasses must be sturdy and durable.Presbyopic glasses are nearsighted glasses. The rule of presbyopia is to use reading distance from 40 years old (+ 1.00d, i.e. 100 degrees), and to supplement it with + 0.50d (i.e.50 degrees) every 5 years.And in the process of using the frequency of wearing tens of times than the nearsighted mirror, so reading glasses parts must be strong or high elastic material.The anticorrosion and anti-scratch performance of electroplating must be outstanding, and the hardening process of the lenses should be good. In general, it should be guaranteed not to be seriously deformed, rusted and rubbed in 2 years.In fact, to a good reading glasses in these points on the requirements should be higher than the same grade with glasses.