What is the difference between a progressive multifocal lens and a normal lens?

1. Different characteristics

Defocused lenses are generally made by adding compounds such as titanium oxide to the glass to make the lens thinner and lighter. It is suitable for making high-gloss lenses. Its refractive index is about 1.7, Abbe number is about 40, and its specific gravity is 2.99. The disadvantages are Large dispersion, easy to produce rainbow effect, and soft nature.

Lenses are transparent materials with one or more curved surfaces made of optical materials such as glass or resin. After polishing, they are often assembled with spectacle frames to form glasses, which are used to correct the user's vision and obtain a clear vision.

2. Different functions

The degree changes point by point from top to bottom on the progressive band in the middle of the lens. The progressive multifocal lens has a gradual vertex power in the entire lens or the transition area of the lens, and is composed of four parts: the high beam zone, the gradient zone, the near beam zone and the aberration zone. Among them, the high beam area is in the upper part, the gradient area is in the middle part, the low beam area is in the lower part, and the aberration area is in the lower part.

The main raw material of glass lenses is optical glass, which has superior optical properties, good light transmittance and mechanical and chemical properties, constant refractive index, and stable physical and chemical properties; secondly, glass lenses have a higher refractive index and are often used for lenses. The highest refractive index is 1.9. Finally, the glass lens has a high surface hardness and is more resistant to abrasion.

3. Different functions

Lenses on the market usually include spherical, aspheric, double-sided aspheric, single-vision or multi-focal visual designs, etc. A good visual design can improve the reality of visual objects, relieve visual fatigue, and improve the wearing experience of consumers.

When using your eyes at close range, when the light is poor (too bright/too dark), the eyes will over-adjust, and after a long time, it will affect vision, so these situations should be avoided. If you are not sure about the light at home, you might as well use an eye protection pen for daily monitoring.