How Do Bifocal Glasses Work?
After learning some basic information about bifocal lenses, you should know how the bifocal glasses work.
With a pair of bifocal glasses, it would be convenient since they combine all your vision needs into a pair of glasses and you do not need to switch two pairs of glasses frequently. Bifocal glasses are usually designed to for those people who are over the age of 40-45 that need additional help with their near vision due to the effects of presbyopia where the crystalline lens inside the eye naturally begins to lose its ability to focus on near objects.
If you work in the office, you may need a pair of bifocal glasses. The top distance vision in the top of the lens can be used for meetings or presentations and the near vision in the bottom of the lens can be used to look at the computer screen or at documents.
What Are Single Vision Lenses?
What are single vision lenses? You may have the same question. Single vision lenses have only one prescription for a given distance. Most reading glasses and distance glasses have single vision lenses because they are designed for people who are difficult in seeing either near or far. Some people are using their single vision glasses for both far and near depending on their types of prescription.
You can choose to wear single vision reading glasses to correct your eyesight if you have trouble reading text on your phone or computer screens. You can also wear single vision glasses to help you make out traffic signs while driving.
Single vision lenses for farsightedness are thicker at the center than those for nearsightedness, which are thicker at the edges. And the single vision lenses generally range between 3-4mm in thickness. The thickness varies depending on the size of the frame and lens material chosen.
After learning some information about one lens glasses, do you know the benefits of them? So, in the following part, we will show you the advantages of single vision lenses.
How to Test Blue Light Glasses (Amber and Red Lenses)
This section will show you how to test blue light glasses with amber or red lenses.
1. The Black and Blue Squares Test
1. Prepare black and blue paper.
2. Wear your blue light glasses after sunset and check whether both paper appear black.
3. If they do not appear black, your blue light glasses can’t block all blue light.
2. RGB Color Chart Test
1. Prepare an RGB color chart as follows.
2. Wear your blue light block glasses and look at the chart.
3. After wearing blue light blocking glasses, if the B section becomes black and the G section becomes darken, it shows that your blue light glasses block blue light and some filter some green light.
4. The less bright the green circle with your blue light glasses, the better they are.
Besides the above ways, you can ask the professional optician to perform a professional blue light glasses test, which would be more reliable. After that, you can know whether your glasses work effectively to block blue light.
What’s more, if you want to purchase a pair of effective blue light blocking glasses, you can try Koalaeye Optical. It is cheap and provides free shipping services.
Types of Bifocal Lenses
Executive: in this type of bifocal lens, the lens is separated completely from each other and the upper part of the lens and the lower part of the lens are divided into two equal halves. There is a distinction line and it is visible.
Progressive lens: these types of lenses are more popular than the other kind of lenses. There is no line in the progressive lens. There is a slow transition of the power from the upper part of the lens to the lower part of the lens.
Progressive multifocal lenses: a progressive multifocal lens gradually changes power from the upper part of the lens to the lower part of the lens and gives a smooth transition between the two different types of bifocal lenses. There is no distinction line in the lens. They are popular because they provide better adaption, comfort, and clarity than the other lenses.
Choose high-quality lenses.
As resin lens technology becomes more and more mature now, resin lens has gradually become popular, so the use of resin lens is the trend. Now resin coated lenses are very popular now. There are anti-reflection films and hard films (anti-wear films) anti-UV films. Anti-reflection film can improve the transmittance of light, making people see more clearly, at the same time, because it can reduce the reflection, the lens is more beautiful in appearance. Hard coating films can effectively protect the lens surface from wear and tear and can resist the damage of hard objects, to prolong the life of the lens. UV-resistant films block the harmful ultraviolet rays of sunlight. For example, the UV400 lens is good for engineers who work outdoors for a long time.
Optometry for prescription glasses
The key prerequisite for proper glasses is accurate optometry. In foreign countries, professional optometrists are generally required to be qualified to issue prescriptions for optometry. However, this is not very standardized in China. Many optometrists have only been trained for a short period of time and do not have the basic knowledge of ophthalmology. For some complex situations, they may not give a proper prescription for glasses. Therefore, optometry should choose a qualified institution. If you are adolescents, people with high myopia, people with anisometropia, etc., you may need to dilate your pupils for optometry. It is best to go to the optometry center of the hospital for optometry
How To Use Contact Lens Correctly?
It is not recommended to use contact lenses when they are dry. Because when they are dry, even the nursing vacuole is used, the parameters change. It will affect the comfort of wearing, so it is recommended to replace the new lens. After the nursing liquid is used every time, you should cover the lid tightly. Do not touch the mouth of the bottle with your hand. If expired and unused, it should be discarded and replaced with new nursing fluid. As for your discomfort, you should return to the store for inspection.Contact lenses and glasses should be used interchangeably.