Inferior optical lens is often accompanied by scratches, stripes and other surface defects, may cause metamorphopsia, fuzzy, make people feel dizziness, headache, nausea etc..
If the glasses do not meet the needs of people's vision, will have a direct injury to the patient, so that eyeglass wearers feel strongly headache or uncomfortable.
If the optical center of eyes is not the same, there will be double image, the eye muscle imbalance, the occurrence of visual fatigue, strabismus, amblyopia and other consequences.
Inferior mirror of sunglasses a lot of visible light absorption, while the eyes harmful ultraviolet able to pass through.
In short, buy inferior glasses just like the patient to eat fake, as serious harm. So with optical lens should go to a professional optical shop.