How to measure glasses

If you want to change glasses, if you need the previous eye degree, you need to re-measure the eye. At this stage in the optical shop there is an instrument called the vertex power meter, vertex power meter as long as the lens is placed under the lens of the power lens, after the adjustment of the instrument, it will automatically measure the degree of the glasses and the axis of astigmatism to diffuse light, these will be accurately measured. 2, pupil distance measurement to be accurate;3, need to try on. The result of the try is to see things clearly, no discomfort, this is a better glasses requirements. If there is halo or see things do not adapt, then the glasses should be readjusted.