The quality of glasses as a product to protect eyewear is particularly critical. How can you tell the difference between good and bad eyes? Experts have good insights on this. The eyewear market is one of the main places for students to spend their holidays, and the quality of the eyewear as a product to protect them is especially critical. In this regard, professionals taught a simple test method to identify the merits of glasses. The professionals said that the main tool to check the quality of glasses is the optical mirror degree meter. Although it can be accurate, but for the average consumer, the more operational abbreviated test method seems to be more convenient. Testing methods are mainly the following 3: 1, test the transparency and optical uniformity of the lens: handheld lens from the front of about 30 cm, from the lens to observe the distant scene, if the scene is clear, no deformation, and no jump when moving slowly, it means that the transparency and optical uniformity of the lens are better. 2, test optical center displacement: draw a large cross on white paper with a fine pen, the stroke should be clear and straight. Hand lens placed between the eye and the cross, with one eye from the mirror to observe the shape of the cross stroke, if the mirror inside and outside the stroke is not in a line, can move the lens, so that the lens inside the cross stroke and the mirror outside the cross stroke into a line. With a brush or tap pen in the lens cross center point a small point, this point is the optical center. After pointing out the optical center of both lenses, observe and compare whether the optical center is symmetrical on both sides, and measure with a small ruler whether the distance between the two centers is the same as the prescribed pupil distance. If the cross stroke in the lens is bent, it means that the lens has internal stress or uneven optical density. 3, determine the axial direction of astigmatism lens: the lens will be rotated at 30 cm above the cross graphic, the cross in the lens can be seen to cross movement, to be connected to the cross graphic strokes inside and outside the lens, the graphic is a positive cross, at this time the column mirror axis and straight line, and then the lens are repeatedly moved along the straight line; observe which straight line in the movement and the lens outside the straight line is more wrong, this line is the direction of astigmatism axis. Move the lens so that the inner and outer straight lines are aligned, and this is the astigmatism axis. The angle between the axial and horizontal lines is measured with a protractor at the center of the lens after marking on the lens, which is the axial degree.