Testing of aspheric lens
The optical axis of the optical center just overlaps with the visual axis of the eye, which is the most ideal state. Because the light from the edge cannot form a focus on the optical axis, when the optical axis does not overlap with the visual axis (the difference is greater than 2mm), such unclear and scattered imaging results will occur. When choosing frames and aspheric lenses, you need to ensure that they fit correctly, to achieve the best visual and decorative effects. Simply put, due to the special design of the lens, we found through a calculation that the optical center should move down 1mm higher than the pupil for every 2° increase in front inclination angle. Otherwise, the wrong pupil height will cause the lens to look like astigmatism, and cause discomfort. For glasses with aspheric lenses, there must be an inclination angle after wearing. The specific angle varies from person to person.
Does the phone screen have irregular color bars when wearing polarized lenses?
It is mainly the special properties of the polarizing film. The polarizer is able to see the internal stresses in the plastic, so when we usually look at the edge of the mobile phone screen, it will have a colored stripe or a black piece, which is mainly caused by the uneven edge pressure when the screen is installed. It's mostly a matter of light and shade. Wearing a polarized lens to see the LCD screen a tilt will find that the screen darkens, mainly because the polarizing lens can absorb light in a certain direction. The LCD screen is a one-way light (different from sunlight), so it is absorbed, so it is found to be dark.
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Why Are My Progressive Lenses Blurry?
So, why are my progressive lenses blurry on sides? It can be caused by a lot of reasons, and we will list some of them.
The strength of progressive lenses is the factor that leads to initial peripheral blurriness. Progressive lenses tend to be blurry on the sides because each lens promotes three fields of vision. In addition, peripheral blurriness or haziness is a sensation that typically develops because more than one lens has been incorporated into one lens. The wearer also might feel as if he or she is moving from side to side.
After learning what may cause progressive lenses blurred, so how can you adapt to the progressive lenses? Therefore, in the following section, we will show you how to get used to progressive lenses.
How are we nearsighted?
The light from external objects to the eye needs to be refracted by the lens before it can be imaged on the retina. The refractive power of the lens depends on the contraction and relaxation of the ciliary muscle. When we look at close objects, the ciliary muscles contract and the lens becomes thicker. When we look at distant objects, the ciliary muscles relax and the lens becomes thinner. Adjust the focal length of near and far objects so that they will show a clear image on the retina. If you use your eyes too often and the longer the ciliary muscles work continuously, the ciliary muscles will spasm because of too much tension. At this time, the lens cannot be adjusted and thinned. After the light from a distant object is refracted by the lens, the imaging position will fall in front of the retina instead of on the retina. Only a blurred image can be seen, which becomes myopia.
There is another situation. For some people, due to genetic factors, in the process of growth and development, the front and rear wheelbase of the eyeball will gradually become longer. In this way, although the adjustment function of the ciliary muscle and the lens is normal, the image formed will also fall in front of the retina due to the longer the axis distance of the eyeball, which can also cause myopia.
The two causes of myopia are different. Myopia caused by ciliary muscle spasm is called 'pseudo-myopia'. As long as the ciliary muscles are relaxed, myopia can be reversed. Myopia caused by the extension of the wheelbase of the front and back of the eyeball is called 'true myopia', which cannot be reversed and can only be corrected by myopia glasses.
Apart from memory metal frames, what other frames are the most durable?
Nylon plastic frames are the most durable frames available. It is hypoallergenic and flexible. But they are easier to break than metal frames, and their overall strength is reduced by sunlight and the aging process. Titanium and titanium alloy metals are used to make some of the most durable frames. Their strength can be compared with that of stainless steel, but titanium frames provide more options than stainless steel in terms of texture, pattern, and color.
What does vision insurance cover?
Vision insurance and vision benefit plans usually cover the cost of annual eye exams, prescription glasses, and/or contact lenses. Vision insurance includes traditional health/medical policies and health/discount plans that provide vision benefits and cover most. Coverage will vary depending on the type of vision insurance or vision benefit plan you choose. Group vision insurance is usually provided through an employer, an organization, or a government plan like Medicare or Medicaid. If you don't qualify for any of these options, you can purchase a personal vision care plan from a vision insurance provider.
