SETO 1.56 Photochromic Round top bifocal Lens HMC/SHMC

As the name suggests the round bifocal is round at the top. They were originally designed to help wearers reach the reading area more easily. However, this reduces the width of near vision available at the top of the segment. Because of this, round bifocals are less popular than the D Seg. The reading segment is most commonly available in 28mm and 25mm sizes. The R 28 is 28mm wide at the centre and the R25 is 25mm. Tags:Bifocal lens,round top lens,photochromic lens,photochromic grey lens

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1)What is bifocal lenses?      Bifocals are lenses with two distinct corrective powers.  Bifocals are commonly prescribed to presbyopes  which require a correction for myopia  (nearsightedness) or hyperopia  (farsightedness) with or without correction for astigmatism (distorted vision as a result of irregularly shaped lens or cornea).  The primary purpose of a bifocal lens is to provide the optimal focus balance between distance and near vision.      Generally, you look up and through the distance portion of the lens when focusing on points farther away, and you look down and through the bifocal segment of the lens when focusing on reading material or objects within 18 inches of your eyes.It is generally accepted that Benjamin Franklin invented the bifocal. The most common bifocal today is the Straight Top 28 Bifocal which has a straight line across the top with a 28mm radius. There are several varieties of  straight top bifocals available today including: Straight Top 25, Straight Top 35, Straight Top 45 and the Executive (The original Franklin Seg) which runs the complete width of the lens.      In addition to straight top bifocals there are completely round bifocals including Round 22, Round 24, Round 25 and Blended Round 28 (no definitive segment).   The advantage to the round segment is that there is less image jump as one transitions from the distance to the near portion of the lens.2)What is photochromic lens? Photochromic lenses are also known as “photosensitive lenses”. According to the principle of reversible reaction of light color alternation, the lens can quickly darken under light and ultraviolet radiation, block strong light and absorb ultraviolet light, and show neutral absorption to visible light. Back to dark, can quickly restore colorless transparent state, ensure the lens transmittance. So the color changing lens is suitable for indoor and outdoor use at the same time, to prevent sunlight, ultraviolet light, glare on the eye damage.Photochromic lenses are also known as “photosensitive lenses”. According to the principle of reversible reaction of light color alternation, the lens can quickly darken under light and ultraviolet radiation, block strong light and absorb ultraviolet light, and show neutral absorption to visible light. Back to dark, can quickly restore colorless transparent state, ensure the lens transmittance. So the color changing lens is suitable for indoor and outdoor use at the same time, to prevent sunlight, ultraviolet light, glare on the eye damage.  3) What is the difference between HC, HMC and SHC?
       Hard coating     AR coating/Hard multi coating        Super hydrophobic coating
makes the uncoated lens hard and increases the abrasion resistance increases the transmittance of the lens and reduces surface reflections makes the lens waterproof, antistatic, anti slip and oil resistance

1.56 Photochromic Round Top Bifocal lens

Model: 1.56 optical lens
Place of Origin: Jiangsu, China
Brand: SETO
Lenses Material: Resin
Function Photochromic& Round top
Lenses Color Clear
Refractive Index: 1.56
Diameter: 65/28 mm
Abbe Value: 39
Specific Gravity: 1.17
Coating Choice: SHMC
Coating color Green
Power Range: Sph: -2.00~+3.00  Add: +1.00~+3.00 

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