For infants and young children who cannot check their vision, it is necessary to comprehensively consider whether prescription glasses are needed, including the degree of hyperopia after dilated pupils and optometry, whether there is a family history of hyperopia and esotropia, whether there is esotropia and the visual behavior status of the child.
To make a judgment, it is necessary to comprehensively consider these factors. Generally speaking, children without glasses can overcome hyperopia of approximately 4D diopter, and if this limit is exceeded, symptoms usually occur. When we need to use half of our regulatory reserves (with a regulatory force of 10-12D), symptoms will occur.
Therefore, if children have 4D hyperopia, they can use adjustment force to overcome it when they look far. But when they look near and outside, plus the increased 3D adjustment needs of looking near, the total adjustment needs is+7D, and Eye strain will appear accordingly.
Adults over the age of 40 often have a reduced adjustment reserve of 4-5D, with half of the adjustment reserve being 2-2.5D, which cannot effectively meet the 3D adjustment needs during close-ups. Therefore, symptoms are prone to occur during close-ups, and the earliest symptoms are often blurring, headaches, or eye fatigue. This is the same as the Eye strain symptoms of hyperopia children, and a hyperopia mirror can well alleviate these symptoms.