| Thin eyeglasses bring attractive appearance and | | | | so that high-index plastic lenses are lighter than |
| light ones bring comfort. Thinner and lighter | | | | conventional plastic lenses with the same vision |
| high-index lenses are the perfect choice for | | | | correction effect. High-index lenses can also |
| wearers who pursue these features. A common | | | | benefit from an aspheric lens design, which makes |
| sense is that lenses for myopia correction are | | | | them flatter and enhance their appearances. |
| thicker at the edge and thinner at the center. | | | | High-index materials have different “index of |
| Stronger prescriptions require thicker lens edges. | | | | refraction”. Lens materials with higher |
| With the prevalence of rimless and semi-rimless | | | | refractive indexes can make the lens thinner, |
| eyeglass frame styles, those conventional plastic | | | | which explains why high-index lenses are thinner. |
| or glass lenses’ thick edges are even more | | | | Conventional plastic has a refractive index of 1.50, |
| obvious, which can detract from the eyeglass | | | | and that of glass is 1.52. High-index plastic and |
| appearance. | | | | glass are now available with refractive indexes |
| The prescription of a lens is determined by the | | | | between 1.53 and 1.74. Lenses made of high-index |
| amount of light refraction that your myopic eye | | | | materials are thinner than that made of low-index |
| need. A higher prescription requires the lens to | | | | materials. It is estimated that a lens with a 1.70 |
| bend more light to provide clear vision. For | | | | index can be at least 50% thinner than a |
| instance, a person with a prescription of -5.00 | | | | conventional plastic lens. |
| diopters needs more light refraction than an | | | | In fact, only high prescriptions require high-index |
| individual with a -2.00 prescription. And stronger | | | | lenses, and the highest index materials are usually |
| minus lenses require thicker lens edges. In fact, | | | | for the strongest prescriptions. You should |
| myopia in most people progresses as they age, | | | | evaluate your prescription needs in deciding proper |
| which means the lens edge will also grow in | | | | high-index materials, since higher index lenses cost |
| thickness. | | | | higher fees. |
| High-index materials can bend light more | | | | High-index lenses with anti-reflective lens coatings |
| efficiently, making myopic lenses have thinner | | | | can transmit 99.5% of the light, reducing light |
| edges than that of conventional plastic lenses with | | | | reflection from the lens surface. As a result, visual |
| the same prescription. This efficiency reduces the | | | | clarity can be ensured, which is advantageous for |
| materials that are used in high-index lenses, while | | | | night driving. Reflection reduction even makes |
| ensuring enough myopia correction. Thinner lenses | | | | high-index lenses appear thinner. |
| in turn decrease the overall weight of the lenses, | | | | |