Operation and Requirements of Drop Ball Test
The ball, which is 0.625 inches in diameter and weighs 0.56 ounces (16 grams), falls from 50 inches (127 centimeters) and hits the center of the lens. The geometrical center of the lens should be struck by the ball within a circle 5/8 inches in diameter. If the lens does not break, it is called a safety lens. There can't be anything that restricts the ball from falling. It cracks across the entire thickness, containing laminated layers (if any), and divides into two or more separate sections across the entire diameter.
What To Do with Old Glasses?
What to do with old glasses? Where can I donate old glasses? You may have the same troubles. So, in this section, we will show you what you should do with your old glasses.
You can choose to donate your old glasses. Around the world, about 13 million children can’t finish their education for the sole reason that they can’t see well enough to learn. In addition, there are some goodwill organizations that will take your used reading glasses as long as they are in decent shape. So, what to do with old glasses, donate them. Where can I donate old glasses? You can search the old glasses donation organizations online.
If you have a pair of old glasses, you can also choose to sell them online to save some money. You can sell them on some platforms such as eBay or Preloved.
Should I wear glasses all the time for myopia?
Whether it is false myopia or true myopia, as long as a pair of suitable myopia glasses are used to complement the missing refractive power of the lens, the image of the object can fall on the retina again, and the distant objects can be seen again. Adolescents usually use high eye intensity and often wear myopia glasses, so that the ciliary muscles do not need to be 'so tired' to adjust, which can avoid further aggravation of pseudomyopia. However, adolescents are still in the process of development, and the degree of true myopia will gradually increase with age. Therefore, as the degree of myopia develops, refraction should be performed at regular intervals, and appropriate glasses for myopia can be prepared to prevent false myopia.
For adults under 200 degrees, because the degree is relatively light, they can wear glasses when they are looking at the distance and not wear glasses when they are near, which has little effect on vision. But for adults with high myopia, because of the weak adjustment ability of the eyes, it is recommended to wear glasses regardless of near vision or distance vision.
In summary, wearing myopia glasses is to reduce eye fatigue and prevents the occurrence of false myopia. Wearing myopia glasses from time to time may aggravate the degree of myopia, and wearing them often does not cause a burden on the eyes. Therefore, for myopia glasses, wearing them frequently is the most correct way to wear them.
What Are Varifocal Glasses?
Varifocal glasses, also known as varifocals, varifocal lenses, or progressive lenses, have a gradual change in strength from the top of the lens to the bottom with multiple focal points in between. Unlike bifocals, varifocal glasses have no specific area of lens strength, but progressive lens zones.
Varifocal glasses have three different prescriptions in one pair of glasses, allowing you to correct near and far vision. And it is convenient for you since you don’t have to change the glasses frequently.
What Are Pinhole Glasses?
Pinhole glasses, also called stenopeic glasses, are plastic eyewear with hundreds of pinhole-sized perforations in place of lenses. Pinhole glasses are mostly used to improve refractive errors in the eye because they shield the eye from indirect rays of light which can distort vision. This would decrease the blur circle on the back of the retina.
How long does it take to get used to progressive lenses?
Because the adjustment of each eye is different, so there will be some differences in the adaptation period. It usually takes about two weeks to get used to it. Probably many young people are familiar with this kind of lens, so they adapt to them for only a week or so and can restore the normal visual effect. If it's been two weeks and you still feel that you can't see clearly, or you have the feeling of nausea, etc., then you need to test and adjust. You need to go to the hospital to see the specific case, to find out whether it is a quality problem of the sunglasses, or there are some artificial reasons. If there is a problem, we should also replace the lenses in time, otherwise, it may lead to the problem of visual fatigue. Therefore, it is still necessary to promptly confirm the case of optometry, and then replace the appropriate glasses.
HINDAR blue light blocking glasses
With advanced equipment, system production, and strict management, they adopt German technology and PARUPU lens geometric structure owned by HINDAR OPTICE LAB, which can effectively block various kinds of blue light, ultraviolet light, and other different wavelengths, to protect the health of eyes. Since its inception, Hindar has enjoyed a lot of popularity, and while it has achieved some good results, it has not slowed down and is still striving to become the top brand in the industry.
