The forward tilt angle is the angle between the discountglasses frame surface and the vertical plane of the frame. Glasses with different tilt angles have different positions where objects are imaged through the lenses.

Wearing eyeglasses online with cheap frames with non-standard front tilt angles for a long time can have a significant impact on the patient's visual habits, causing discomfort such as deformation when wearing new lenses. In this case, it is advisable to allow the patient to adapt to the new lenses as much as possible. If adaptation is difficult, the front tilt angle can be adjusted appropriately according to the old lenses.

Eye distance is the distance between the posterior vertex of the cheapest eyeglasses lens and the anterior vertex of the cornea, measured in degrees without touching the eyelashes. For positive lenses, the effective refractive power of the lens to the eye increases with the distance from the posterior vertex of the lens to the cornea; The effective refractive power of negative lenses decreases as the distance from the posterior vertex of the lens to the cornea increases.

When the distance between the lenses is too large or too small, it can have an impact on corrected vision. When customers wear old glasses with a nose rest and replace the new glasses with frames without a nose rest, it is necessary to observe the near-eye distance after wearing them. If it is found that the near-eye distance of the new glasses is particularly close, it can be considered to adjust the degree of myopia appropriately to avoid discomfort during wearing.

It is best not to prescribe new glasses in one step, but to gradually correct them step by step. The older the age, the higher the degree, and the longer the time the old glasses are worn, the longer the adaptation period will be required, and the changes should be smaller.