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Progressive eyeglasses are nowadays popular in the market, there are different brands for you to choose from. This article is mainly about zeiss progressive eyeglasses lenses, which may be unfamiliar to some people. Here lists some advantages and disadvantages of such lenses.

Disadvantages

Distortion: Progressive lenses suffer the disadvantage of the power progression creating regions of aberration away from the optic axis, yielding poor visual resolution (blur), which varies in relation to the quality of the lens. As the lenses combine a range of powers in a single surface there are also geometric distortions to the visual field, which increase with the addition power. Some wearers find the visual discomfort caused by these distortions outweigh the benefits of wearing PALs. However, manufacturers claim acceptance rates of 90%-98%. Clinicians generally agree that in order to avoid adaptation problems it is best to start wearing progressive lenses early in the development of presbyopia (around 40 years of age for most people) while the prescribed addition powers are low. The wearer can then adapt to the increases in a series of steps in addition power over a number of years as their presbyopia progresses.

Availability: Progressive lenses use highly complex proprietary curves in combination with the patient’s basic bifocal prescription and measurements. All lens-curve types—there are hundreds—are not available from all opticians. A patient may be able to get what is prescribed from few local opticians, or only from the prescribing optometrist; however most optical establishments offer a variety of multifocal lens qualities.

Peripheral Vision Loss: Because of the narrow vertical range of undistorted vision, there is an inherent loss of peripheral vision with progressive lenses, as with all prescription spectacle lenses. This loss of peripheral vision and the resulting side vision distortion may result in the wearer not being able to see more than 25% of a computer display without having to move the wearer’s head from side to side to clearly see and comprehend the monitor’s content, however for wearers who use computers regularly and for prolongued periods of time, many optical practitioners recommend a progressive lens tailored specifically to the intermediate and near prescription for computer and reading use.

Cost: Progressive lenses are generally dispensed at a higher price than bifocal and single-vision reading spectacles due to the increased manufacture and professional service costs.

Fitting: Progressive lenses require careful placement relative to the wearers pupil centre for a distance’-viewing reference position. Incorrect specification of the fitting location can cause problems for the wearer including narrow fields of view, clear vision in one eye only, on-axis blur, and the need to adopt uncomfortable head positions.

Because of the relatively narrow vertical band of prescriptively accurate optics characteristic of progressive lenses, wearers may have some difficulty becoming used to the coordination of horizontal head movement necessary to retain focus when reading across a computer screen or a paper page. This is particularly true when the reading add power is strong (+2.00 or above). The experience has been described as “moving your head back and forth as if you are watching a tennis match”. This can be mitigated by using high quality lenses, and by having your glasses made and fitted by a competent optician who is experienced in fitting progressive lenses. It is also beneficial to avoid the shallow eyeglass frames (i.e. the frames with very small vertical dimension) and choose a frame that is somewhat larger instead.

Advantages and use

The lens location of the correct addition power for the viewing distance usually only requires small adjustments to head position, since near vision tasks such as reading are usually low in the visual field and distant objects higher in the visual field.

Progressive addition lenses avoid the discontinuities (image-jumps) in the visual field created by bifocal and trifocal lenses and are more cosmetically attractive. Since bifocal and related designs are associated with ‘old age’, proponents have suggested the lack of segments on the lens surface of a progressive lens appears more ‘youthful’ since the single vision lenses associated with younger wearers are free of segments or lines on the surface.

The wearer can adjust the additional lens power required for clear vision at different viewing distances by tilting his or her head to sight through the appropriate part of the vertical progression;

Zeiss progressive eyeglasses lenses can not be suitable to everyone interested in them. You need to know both their advantages and disadvantages before purchasing. Selection involves multiple tradeoffs among near, mid, and far vision quality and in factors which empirically affect visual ease-of-use.