With glasses, did you choose the right refractive index?

1) What is the refractive index?

The higher the refractive index of the material, the stronger the ability to refract the incident light. The higher the refractive index, the thinner the lens, that is, the same thickness of the lens center, the same degree, the same material, and the higher the refractive index, the thinner the edge of the lens than the lower refractive index. Generally speaking, the higher the refractive index, the lower the Abbe number, that is, the lower the definition, but not absolute.

2) 1.5 Refractive index

It is a good choice for people with low myopia or low hyperopia. Although it is the thickest lens, the Abbe number reaches 58, which is the clearest lens. It is recommended that people within -2.00 or+2.00 should choose.

3) 1.56 Refractive index

1.56 is rarely used in foreign countries, and most of them are farsighted. They pay more attention to the clarity. They prefer 1.5 lenses, which are relatively fragile. They are not suitable for half frame or no frame. Because they are easy to crack, they are not recommended refractive indexes. Suitable for people within -3.00.

4) 1.591 refractive index

The unique refractive index of the universe chip or PC chip. This material has obvious advantages and disadvantages. Because of its super toughness, it is often used as labor protection glasses, bulletproof clothing, aerospace clothing masks, etc. It is light in weight, but its visual effect is very poor. Abbe number is only 31, there is internal stress, and it is not wear-resistant. It is generally not recommended to choose 1.591 as the eyeglass. Unless low myopia or hyperopia chooses no frame or half frame, it will be considered.

5) 1.6 Refractive index

The super recommended refractive index and sharpness are relatively high. Moreover, the material has good toughness and is thinner than 1.56. It is not easy to crack when making frameless or half frame. Recommendation 1.6 is the first refractive index to be considered. Flat light to -6.00 can be considered.

6) 1.67 Refractive index:

For people above -6.00, the budget is not particularly high. It would be too thick for people with a high number to choose 1.6, so they can only choose 1.67.

7) 1.71 Refractive index

1.71 The refractive index is high, but the Abbe number is not low, reaching 37. It is thinner than 1.67 and suitable for people in the range of -4.00 to -8.00.

8) 1.74 Refractive index

It is generally believed that 1.74 is the thinnest lens. The relative price is also relatively high. It is especially suitable for people above -6.00. The higher the degree, the more necessary it is to have 1.74- People above 8.00 should not hesitate.