The accuracy of pupil height is related to whether the optical center of the lens corresponds to the reflective point at the center of the pupil. When assembling eyeglasses online, it is usually assumed that the pupil height is high, which is relatively suitable for people with balanced and low diopters in both eyes.

For the above groups of people, the data on pupil height should be as accurate as the pupil distance. If not, it is likely to produce vertical prism effects or the tolerance of both eyes to different amounts of vertical prism, which will affect the comfort and visual quality of wearing glasses.

Pupil distance refers to the distance between the pupils of both eyes. As is well known, in addition to the degree of myopia and astigmatism, eyeglass online matching also requires another important data, namely pupil distance.

Usually, for those of us who wear eyeglasses online cheaply, how can we accurately measure our pupil distance? Hold a standard-sized card as a reference, take a photo of yourself with your phone, and calculate the actual pupil distance based on distance conversion.

The key to taking photos is to maintain an arm's distance, with the card pressed against the lips, the phone and eyes at the same height, and the eyes naturally looking forward. Keep the card level and straight, and keep the head straight.

Lens fitting requires pupil distance, and I think the vast majority of people know that it is necessary data for lens fitting. It is to ensure that the two reflective points of the pupil in the horizontal direction coincide with the optical center points of the two lenses.