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Progressive Lens and it’s fitting

Progressive Lens and it’s fitting

Progressive lenses, also called multi-focal lenses or progressive addition lenses (PAL). Progressive lenses are used in eyeglasses to correct presbyopia and other disorders of accommodation. The power of progressive lenses changes gradually from point to point on the lens surface, providing the correct lens power for seeing objects clearly at virtually any distance.

Bifocals, on the other hand, have only two lens powers — one for seeing distant objects clearly and a second power in the lower half of the lens for seeing clearly at a specified reading distance. The junction between these distinctly different power zones is defined by a visible "bifocal line" that cuts across the center of the lens.

Progressive lenses sometimes are called "no-line bifocals" because they don't have this visible bifocal line. They have a significantly more advanced multi-focal design than bifocals or trifocals.

                    Progressive lenses have three zone, these are distance, intermediate, near.

                              

Benefits of Progressive Lenses:

• It provides clear vision at all distances (rather than at just two or three distinct viewing distances like bifocal or trifocal).
• It eliminates "image jump" caused by bifocals and trifocals. This is where objects abruptly change in clarity and apparent position when your eyes move across the visible lines in these lenses.
• Because there are no visible "bifocal lines" in progressive lenses, they give you a more youthful appearance than bifocals or trifocals. (This may be the reason why today more people wear progressive lenses than the bifocal and trifocals combined.)

Progressive Lenses fitting:

• 1.      Distance reference circle: It is a marked which helps to fitting the lens in the frame.
• 2.      Prism reference point: For a progressive power lens or semi-finished lens blank, that point on the front surface stipulated by the manufacturer at which the prismatic effect of the finished lens is determined.
• 3.      Fitting cross: Fitting cross is the mark which helps to fitting the progressive lens in the frame.
• 4.      Micro etching: It is a mark, done by laser. It helps to fitting the lens in the frame. When the patient takes the new progressive lens secondly, then this micro etching helps to cut and fit the lens in the frame.
• 5.      Add power:  In the progressive lens there is an area where the near power print by the laser.
• 6.      Company logo: In the progressive lens there is an area where company logo printed by the laser.