Combined with the company’s principles and values, are at the core of the Group’s long-term commitment to sustainable development. Our consistent growth in recent years and our leadership position means we continually seek to excel in our standards of corporate citizenship.


What is Blue Light?

As we now live in the digital era, the issue of high-energy visible (HEV) light wavelengths emitted from backlit displays is of concern to eye care providers, specifically the impact of overexposure to blue light on long-term vision health.

Light that appears white can have a large blue light component, exposing the eye to hidden spikes in intensity at wavelengths within the blue portion of the spectrum. These wavelengths range from 380 to 500 nanometers (nm). The band of blue-violet light considered potentially most harmful to retinal cells ranges from 415 to 455 nm. Some of the most favored digital devices and modern lighting — such as light-emitting diode (LED) lights and compact fluorescent lamps (CFLs) that have replaced most incandescent lights — can emit a high level of blue light, typically in the wavelength starting at 400 nm.


BLUE BLOCK (UV420) LENS technology is used to make a UV420 lens material that block high-energy visible (HEV) light in the 400–420 nm part of the spectrum, in addition to blocking all UV wavelengths. This means it provides greater protection against the types of light that can damage the eyes.


Photochromic lenses, change their color from clear to dark and back again. This process is the result of technology using photochromic dyes, allow the wearers to enjoy comfortable vision both indoor and outdoor.


Photochromic lenses only change from clear to dark in the presence of UV light (of which most comes from sunlight). This is because the UV rays interact with photochromic dyes that are added into the lens.

This interaction causes the dye to change shape, substantially increasing its size and subsequent surface area. As the dye increases in size, the lenses get darker. The level of darkness depends on the amount of sunlight the lens is exposed to and the lens quality. At KANGJU optical, our lastest technology guarantee fast change outdoor and fast clear indoor.

Photochromic lenses can be divided into two types: Normal Photochromic (as known as "Material Photochromic") and Coating Photochromic (as known as "Spin Coating").


The material photochromic means that the entire lens will change color when the color changes. So the disadvantage of this type is there will be color difference between thicker and thiner lenses, for example -6.00D will have a darker color than -1.00D after activated.


On the other hand, the color changing of Spin Coating takes palce on the coating layer, which is on the surface of the lens, so there will be no color difference between thicker and thiner lenses.