Why is a prescription for glasses different from a prescription for contact lenses?
The frame glasses degrees are the optometric degrees of the eye, and the difference between the frame glasses degrees and the contact lens degrees is mainly due to the different contact distances between the two lenses and the eye. Usually, degrees of contact lenses and glasses need to be converted by a professional through vertex diopter. The conversion formula is Fc=Fs/(1-d×Fs). In the formula, Fc is the diopter of contact lens, Fs is the diopter of glasses frame lens, and D is the distance between frame glasses lens and cornea. Assuming that the prescription of frame glasses is -4.00d and the distance between lens apex is 12mm, the prescription of contact lenses is -4.00/ [1-0.012×(-4.00)] = -3.82d.
Progressive lenses and single vision lenses
Single vision lenses are the most commonly used prescription lenses. This lens type has a single field of view or a prescription ability of the entire lens and can be used to correct myopia (nearsightedness) or hyperopia (supervision).
Progressive multifocal lenses are lenses with different upper and lower powers for the upper part to see far, and the lower part to see near. The distance from the fixed power above the lens to the fixed power below the lens does not change suddenly, but there is a gradual transition between the two through the gradual change in refractive power.
Blue light and anti-reflective lenses
They reduce the potential for cumulative damage to the eyes.Allowing the beneficial blue light through improves clarity, they reduce glare and reflection. They can improve your visuals and reduces eye strain and nighttime reflexes. They can reduce the symptoms of computer vision syndrome, including eye strain, eye strain, and headache.
The role of the driving glasses
Good driving glasses can be very good to block high energy light, in the evening they can let more faint light enter into our eyes, really solving the problem of only blocking the light and not blocking the road. They have very good night vision function, and can better eliminate glare, better improve the vision of the driver. The driver can drive safely day and night. Strong sunlight improves visual clarity. They are special driving glasses and can brighten polarized light and improve driving safety. With unisex style, high-definition vision, comfort, and light. It can be used on rainy and foggy days and can be used by myopic people. It can effectively filter strong light and high beam lamps, and the long-term use makes you not tired. Both rainy and cloudy days can improve visual clarity. It can effectively prevent strong light, ultraviolet light, and glare is durable and can solve the problem.
Difference Between Sunglasses and Optical Frame Glasses
Sunglasses are basically applied to block sunlight and adornment effect. But in the choice of lens material and lens craft respect, it is not very particular. Correspondingly, consumer wears for a fixed number of years, to be in one season or two seasons. Sunglasses are sold with obvious seasonality. Optical glasses are mainly suitable for the use of photometric glasses. Both the lens material and the production process have higher requirements. A panchromatic or half chromatic resin lens is added to an optical lens, and then they can be sunglasses and can try luminosity, made of myopic sunglasses.
Look at the quality of the frame.
Put the glasses flat in front of your eyes, and see if the color of the temples is different in-depth or light under the same light intensity. Sometimes, due to the mistakes in processing, the color asymmetry of the left and right temples will appear.Technology is the quality assurance of the frame, and a frame of fine technology is often reflected in the details.Pay more attention to the welding point near the metal frame to see if there are cracks.
The thermal effect during welding changes the stress structure of the material, or the weld defect, material fatigue, and so on will make it easy to fracture.Attention should be paid to see if the two sides of the stipules of the lens frame are symmetrical and if the fixation is safe.
Who are suitable for progressive lenses?
A progressive piece is suitable for most old people to wear. The proper person is the one who has the visual needs of the long, medium and short distance cares about beauty, and is willing to accept new things. In order to avoid binocular vertical prism differences, for the wearer whose equivalent spherical lens with anisometropia is more than 2D, especially if the difference in refractive power of the vertical meridian is more than 2D, it should be checked with caution. Opticians whose vision needs do not match the progressive lens design, like dentists, often experience blurred vision when working with the far side of the lens to look closer.
