FQA
What are bifocal lenses and multifocal lenses? And what is the difference between them?
In principle, when you reach a certain age, it will be yours
Detection of distances and objects that are more than 70 cm away
Another detection for reading and nearby objects that are more than 40 cm away
So there are two solutions:
1- You use two separate glasses, one for reading and one for distance
2- You are using bifocal/multifocal lenses
These are lenses that combine reading and distance detection at the same time, so that you move your eyes in the appropriate direction to achieve comfortable vision for your eyes.
This saves you from having to use more than one pair of glasses or forgetting one of them, which can cause many problems…
Byfocal lenses have a large part for distances and a specific part for reading
Multifocal lenses have a gradient between the distance focus and the reading focus, and this causes more comfort for the eyes during use.
What are compact lenses that are thicker and less weight?
The refractive index of lenses: It is a number that indicates the degree of compression of medical lenses so that they have a thinner thickness and a lighter weight for people who suffer from visual impairment of more than four degrees. As the refractive index increases, the thickness of the lenses decreases and they become lighter in weight. This term is referred to in English as the refractive index.
1- Plastic lenses have several refractive indexes (1.50, 1.56, 1.61, 1.67, and 1.74). Plastic lenses with a refractive index of 1.74 are considered the thinnest plastic lenses ever.
Are block lenses really useful or not?
We will help you and answer everything you think about blue kit lenses
In order to understand the idea of these lenses, we must first understand what blue light means and its risks
First, visible light is divided into seven colors Each color has a wavelength and an energy level The lower the wavelength the higher the energy of the light.
Blue light is one of these colors, and its problem is that it has a higher energy than any visible light, so we call it High Energy Visible light.
The wavelength ranges between
nm 400-500
The problem with blue light is that, due to its high energy, it is able to penetrate many layers inside the eye and reach the retina, damaging it.
It also increases the possibility of a disease called Macular Degeneration
Or macular degeneration, which is considered severe vision loss
Blue light is divided according to its wavelength and the extent of its effect on the eye
1.400-420 nm
This part is responsible for causing glare and also responsible for scattering light
2.420-460 nm
This part is responsible for negative changes in the retina and can cause severe vision loss (AMD).
3.460-480 nm (Circadian Rhythm)
This remains the useful part of blue light because it is very important for regulating the body’s biological clock, which affects the number of hours we sleep and wake up and our mood. It also increases the secretion of hormones that keep us alert and focused all the time, and we are often exposed to this part through the sun.
Unfortunately, with increased exposure to this part, especially at night
Among modern devices such as laptops, mobile phones, and LCD screens
They stop the secretion of these hormones, so we feel uncomfortable and cause sleep disturbances
Preferred types of lenses to resist blue light?
We talked about blue light, its dangers, and its benefits. Here we will talk about how to prevent the harmful part of it
We have two types of lenses
The first type: Material Filter blue light lenses 400 – 420 nm
suppress This is a filter that works with the lens material and prevents OP
Ultraviolet rays and part of blue light, which is 400-420 nm
We agreed that this wavelength causes glare and scattering of light
We call them Blue-vilot light lenses
We have 3 types in the Egyptian market that work using this mechanism or in this way..
1.Pixel Astro Plus 1.56
2.Kodak uv blue 1.56
The second type: Spin Coat Blue light filter lenses
These lenses have their filter on the surface of the lens
It filters out the part that causes damage to the AMD retinal cells, as well as the part that causes glare and scattering of light, 400-460 nm.
It helps the useful part of blue light pass through the eyes and through the eyes
Beneficial blue light part 460 -480 nm
It helps to secrete the hormone melatonin, which is responsible for regulating the body’s biological clock
These antireflection lenses are often blue, and the percentage of yellowing of the white color does not exceed 2%, so they make the colors warmer, making them comfortable for the eyes.
You will not notice a difference in colors at all unless you focus on this topic
We have many types of lenses that operate using this mechanism or method, namely:
BBGR Neva Blue ** % 5 The percentage of yellowing here can reach
.Zeiss Blue Protect
.Hoya Blue Control
What are photochromic lenses (photochromic lenses)?
Photochromic lenses are among the best types of lenses to protect the eyes, as they are sensitive to ultraviolet rays found in sunlight.
The original color of the lens is transparent and light, and its color is often shades of gray or brown When exposed to ultraviolet rays, its color gradually becomes darker. Depending on the intensity of the rays, and because the color of the lens changes and becomes more opaque, this provides protection for the eye and prevents ultraviolet rays from reaching it by more than 90%.