Presbyopia is a kind of convex lens. You can judge whether presbyopia is a convex lens or a concave lens by analyzing the lens thickness and imaging method, and the preparations you need to do before buying a suitable presbyopia.
First, analyze the lens thickness of reading glasses. If it is thick in the middle and thin at the edge, it is a convex lens, which has the effect of a magnifying glass, but it is not equivalent to a magnifying glass. The function of reading glasses is not only to see the words clearly, but also to maintain the eyesight of the elderly, ensure that the eyesight will not decline continuously, and protect the eyes.
Secondly, according to the imaging method in physics, the convex lens has the function of magnifying the object. Put a newspaper on the table, and then use the lens to observe the words on the newspaper. If the words are magnified by multiple, it is a convex lens, otherwise it is a concave lens.
Before wearing reading glasses, it's best to go to the hospital for optometry. It's like a tailor customizing clothes for customers. The height, waist circumference and weight of customers must be measured first. Presbyopia is a normal physiological phenomenon with the aging of human body, and the crystals in the eyes also weaken the ability to regulate vision with aging. Wearing presbyopia glasses is also to better the daily life of the elderly.