You should use a soft cotton or linen cloth for cleaning, making sure that you only wipe over the lens surface lightly to avoid scratches. If a more thorough cleaning is required, we recommend that you moisten the cloth with lukewarm water.  Never use alcohol-based solvents or organic solvents to clean the lens as these could destroy the lens.

The LEDs used for illuminating Eschenbach Optik products have a virtually unlimited service life. They therefore do not need to be changed.

Check the performance of the batteries and if necessary replace these with new ones. 

You should only use a bulb which complies with the specified voltage and amperage values. You can find the technical details on your magnifier and/or in the operating instructions. If in doubt, please ask your optician for help.

No. For technical reasons, it cannot be used during the 4-hour charging period.

A dioptre (dpt) is the unit of measurement of the optical power of a lens. In the case of spectacle lenses, negative dioptre values correct short sightedness, positive values correct long-sightedness. The dioptre is equal to the reciprocal value of the focal length of a lens measured in metres: a power of +5 dpt therefore has a reciprocal length of 1/5 metres or 20 centimetres.

In the case of long-sightedness, the eyeball is too short. The focal point of the eye is behind the retina. Your near vision is then blurred, e.g. when reading. When the eye compensates through accommodation, this often leads to eye strain, fatigue and headache. Plus powered lenses, which bundle the incoming light, can be used to correct long sightedness.

Hyperopia is the medical term for long-sightedness.

In the case of short-sightedness, the eyeball is too long. The focal point of the eye is in front of the retina and your distance vision will be blurred. The eye is not able to compensate for short-sightedness itself through its own accommodation. Only glasses with minus powered lenses can correct short-sightedness by moving the image back to the retina.

Myopia is the medical term for short-sightedness.

As we age, the power of accommodation, i.e. the adaptability of the eye decreases. Objects in our near vision appear blurred. This process usually becomes apparent between the ages of 40 and 65. You will then need a pair of glasses to be able to read at a normal distance of approximately 35 centimetres. The power of your reading glasses depends on your remaining power of accommodation.

Presbyopia is the medical term for age-related long-sightedness.

An eye is described as having a vision defect when it has less than normal vision. The term is very imprecise, as a vision defect can have a wide variety of causes and characteristics. The most common forms are short-sightedness and long-sightedness, which can be corrected through the use of a vision aid. The visual impairment caused by other sight defects, such as night blindness or amblyopia, cannot be corrected.

Amblyopia is a vision defect where the visual loss cannot be corrected by wearing even the best corrective glasses. It can be congenital. This also includes, for instance, strabismic amblyopia. When squinting, a different image is formed in each eye. In order for the brain to be able to see clearly, the brain "turns off" the visual processing of one eye. This unused, untrained eye becomes amblyopic (visually impaired).

As we age, our vision deteriorates and we require more light for high-contrast vision. Effective illumination can therefore significantly improve reading. For this reason, many of the reading magnifiers from Eschenbach Optik are equipped with a powerful LED light. Some also offer different tones of light as the temperature of light can also effect our ability to see.

However, in the case of a clouding of the eye, diffuse glare or dazzling can occur with increased light. In this case, please consult your optician.

High contrast is essential for good vision. Good, glare-free illumination provides a high contrast. In addition, lens coatings, cut-off filters and glasses with side protection can also help. Electronic magnifiers can improve vision by enabling the user to increase the contrast. Further advice on increasing contrast can be obtained from your optician.

Visual acuity is the sharpness with which an object is focused on the retina. Visual acuity (VA) is the most common clinical measurement of visual function. If the visual acuity is corrected through the use of glasses or other vision aids, the new value is expressed as the corrected visual acuity.

In contrast to sun protection filters, which reduce the overall visible light in a relatively even manner, cut-off filters only filter out a specific area of the spectrum, whilst the remaining components of light are able to pass through the cut-off filters virtually unhindered. The areas between transmitted light (transmission) and filtered out light (absorption) are sharply distinct from one another, whereby the mode of action has an angled progression.

The light which is visible to us has a wavelength in the range of 380 nanometres to 780 nanometres. The short-wave, blue components of light are richer in energy than the red components and are refracted more strongly on refractive surfaces than long-wave light.

The light rays emitted from a light source oscillate in waves which are scattered in all directions.

A polarisation filter in a spectacle lens filters out all oscillating light waves which are not vertical, so that only vertically oscillating light waves can pass through it.

If light hits a reflective surface, e.g. a wet road, it is also polarised - this time oscillating horizontally - and cannot pass through the polarisation filter. In this way, the strong glare caused by reflections in particular is filtered out and contrast vision is increased.

Accommodation is the ability of the eye to focus on objects close up by varying the shape of the lens. This ability is lost as we age. The resulting age-related presbyopia can be corrected through the use of reading glasses.

There is no standard answer to this question, as it differs for each vision task: a visual acuity of 0.1 is sufficient for a person to be able to orientate themselves outdoors. However, a visual acuity of 0.8 is required for reading travel timetables. Other minimum values include: 0.4 for watching television, 0.5 for reading the newspaper and 0.7 for reading a telephone directory.

No. In order to be able to read we require a functioning retinal surface of around 2.5 degrees to the left and right of the fixation point, i.e. a visual angle of around 5 degrees in total. A reading angle is necessary as our eyes do not read letter by letter, but through the recognition of whole syllables.

The cera-tec® hard coating is an extremely resilient surface finish, which has been developed in collaboration with the Fraunhofer Institute for Silicate Research (ICS) especially for the lenses manufactured by Eschenbach Optik. It provides the lenses with all-round protection and ensures lasting comfort of vision for the user.

LED magnifiers from Eschenbach Optik provide a very even illumination of the field of view. With only two standard batteries, the necessary voltage is stepped up to the 3.6 volts required. The step-up converter used here guarantees bright, even illumination over a long period of time. If required, the white/blue light can be toned down by using a filter cap.

An aspheric lens has a refractive surface geometry which is not in the form of a sphere. The image quality is significantly improved in comparison to simple spherical lenses and aberrations are prevented or reduced.

In addition to the aspheric properites, diffractive aspheric lenses have a special surface structure which diffracts the light, instead of refracting it. The lenses are thinner and lighter, which offers particular advantages in the case of large magnification values and small magnifier models.

The Fresnel lens refracts the light like a conventional lens, but does not consist of a smooth, curved surface - but different concentric ring zones, which have different optical refractive properties. The lens is therefore significantly thinner with the equivalent refractive value, but loses some of its image quality.

The Fresnel lens refracts light. Diffractive lenses defract light.