1. How bifocal lens work? Bifocal lenses are perfect for people suffering from presbyopia- a condition in which a person experiences blurred or distorted near vision while reading a book. To correct this problem of distant and near vision, bifocal lenses are used. They feature two distinct areas of vision correction, differentiated by a line across the lenses. The top area of the lens is used for seeing distant objects while the bottom part corrects the near-vision2. What is the semi finished lens? Lenses with different dioptric powers can be made from one semi-finished lens. The curvature of the front and back surfaces indicates whether the lens will have a plus or minus power. Semi-finished lens is the raw blank used to produce the most individualized RX lens according to the patient's prescription. Different prescription powers request for different semi-finished lens types or base curves.4. 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

1.499 flat-top semi-finished optical lens
Model:	1.499 optical lens
Place of Origin:	Jiangsu, China
Brand:	SETO
Lenses Material:	Resin
Bending	200B/400B/600B/800B
Function	flat-top & semi-finished
Lenses Color	Clear
Refractive Index:	1.499
Diameter:	70
Abbe Value:	58
Specific Gravity:	1.32
Transmittance:	>97%
Coating Choice:	UC/HC/HMC
Coating color	Green

3. What's the importance of a good semi-finished lens to RX production? ①High qualified rate in power accuracy and stability ② High qualified rate in cosmetics quality ③High optical features ④ Good tinting effects and hard-coating/AR coating results ⑤Realize the maximum production capacity ⑥Punctual delivery Not just superficial quality, semi-finished lenses are more focus on the internal quality, such as precise and stable parameters, especially for the popular freeform lens.