Frequently Asked Questions About Eyeglass Lenses Concerned by Spectacle Wearers
Answer: High-index lenses are also known as ultra-thin lenses, generally with a refractive index above 1.70. Regular lenses feature a refractive index ranging from 1.49 to 1.53. Under the same dioptric power, high-index lenses have a flatter base curve and are 1/5 thinner than regular lenses, making them especially suitable for people with high refractive errors.
High-index lenses deliver higher light transmittance and definition, fewer vortex distortions, lifelike imaging, wider and clearer vision, and less visual fatigue. They are lighter, thinner and more aesthetically pleasing.
Answer: Famous brands including Essilor (France), ZEISS (Germany), HOYA and Nikon (Japan) develop and manufacture lenses with decades of professional optical research experience. They differ from domestic lens brands in technological content, expertise, production craftsmanship and raw materials. Besides, each brand adopts unique substrate and coating systems, bringing distinct performance characteristics.
Nevertheless, imported lenses cannot guarantee that your prescription will not deepen. Myopia progression results from multiple factors. Maintaining balanced nutrition, proper eye use habits and regular physical exercise will help stabilize your eyesight as much as possible.
Answer: Lens coatings eliminate surface reflected light, boost light transmittance, and offer sharper vision, greater comfort and better appearance.
Common surface treatments include hard coating, multi-layer anti-reflective coating, and hard-coated multi-layer anti-reflective coating.
Hard coating increases surface hardness, approaching that of glass. Anti-reflective coating improves visible light transmittance and UV resistance. A buffer coating is also applied on lens surfaces to maintain and enhance impact resistance.
Answer: Resin lenses are made of polycarbonate. They are lightweight, shatter-resistant, capable of blocking UV rays, high in light transmittance and easy to tint. Safer and more attractive than glass lenses, they require more complex manufacturing techniques and thus come at a higher price.
Glass lenses are heavy, fragile and thicker than resin lenses, yet they feature high temperature resistance, greater hardness and superior wear resistance. Both types have their own merits. Resin lenses are recommended for children and teenagers.
Answer:
- Customers with prescriptions below 500 degrees: 1.56 / 1.61 lenses are recommended for cost efficiency and wearing comfort.
- Customers with prescriptions between 500 and 800 degrees: choose 1.61 ~ 1.67 lenses.
- Customers with prescriptions over 800 degrees: opt for high-index lenses from 1.67 to 1.74. Lighter than ordinary lenses, they are the ideal option for high-prescription wearers pursuing premium comfort.
Answer: Light transmittance represents lens clarity, defined as the ratio of light entering the eye through the lens to the total light reaching the lens surface. A higher ratio means better light transmission and clearer vision.
The general standard is above 91%. Uncoated resin lenses reach 84%~90%, while coated lenses achieve up to 98%. Transmittance directly affects field-of-view clarity. Coatings produce optical effects that reduce surface reflection and raise transmittance, resulting in sharp vision.
Answer: If old lenses are not heavily scratched, it is a waste to throw them away. You can match them with an affordable frame as a spare pair. Another practical solution: let children wear the new glasses at school and use the old pair for reading and studying at home, killing two birds with one stone.
Answer: Differences exist in substrate quality, coating performance, light transmission effect, refractive index, thinness, density and abrasion resistance, UV protection capability, intended application, production process and brand value.
Answer: Traditional spherical lenses have lower power at the optical center than at the periphery. They are relatively thick and cause image distortion at the lens edges, known as optical aberration. Meanwhile, the wearer’s facial outline appears distorted when viewed through spherical lenses.
Aspheric lenses adopt an innovative design where the power at the center closely matches peripheral power. They reduce both central and edge thickness for a slimmer profile, deliver a wider field of view without curved edge distortion, minimize aberration and present more natural, lifelike vision with less fatigue after long-time wear.
For the same prescription of -5.00 DS, aspheric lenses are roughly one-third lighter and thinner than spherical lenses.
Under identical refractive conditions, aspheric lenses are lighter, thinner, more attractive and more comfortable to wear. They improve effective field-of-view utilization and visual authenticity. For patients with high astigmatism, they reduce image distortion; for those with anisometropia, they ease diplopia (double vision).