When the lens of a sunglass is scratched, you can consider the following treatment methods:

Evaluate the degree of scratches:
First, you need to evaluate the severity of the lens scratches. Minor scratches may only be surface wear, while deep scratches may affect visual effects.
Clean the lens:
Before any repair or treatment, gently wash the lens with clean water and a special cleaner to remove surface dirt and grease.
Use repair fluid or repair pen:
If the scratch is shallow, you can try to repair it with a special lens repair fluid or repair pen. These products can usually be purchased in optical stores or online.
When using, please read the product manual carefully and follow the instructions. Generally speaking, the special ingredients in the repair fluid or repair pen can fill minor scratches and restore the clarity of the lens.
Seek professional repair:
If the scratch is more serious or the repair fluid/repair pen cannot solve the problem, it is recommended to go to a professional optical store or repair center for repair.
Professional repair usually involves the use of professional polishing tools and techniques to remove scratches and restore the original condition of the lens. However, it should be noted that severe scratches may not be completely repaired, or repair may affect the UV protection of the lens.
Replacing lenses:
If the scratches on the lens cannot be repaired or the repair effect is not good, it is recommended to consider replacing the lens.
When replacing the lens, please make sure to choose the same or better material and specifications as the original lens to ensure the stability of UV protection and visual effects.
Precautions:
In order to avoid lens scratches, it is recommended to pay attention to the protection of sunglasses during daily use. Do not put sunglasses together with hard or sharp objects to avoid scratches and collisions.
When cleaning the lens, please use a special cleaner or mild detergent, and avoid using chemical solvents or rough cloth.