Spectacle lenses can be mono or multi focal and that is the main factor affecting the price formation. The choice of various materials and surface coatings affecting the weight and durability of the lenses also influences the price.
More expensive eyeglasses lenses are of a higher optical quality and thus better for your eyes. Lenses of a more expensive price class are often made of a durable and lighter material, wear long and are more comfortable to use. Hard surface and antireflection coating improve vision as the lenses do not get scratched so easily and the image is clearer. You see well with discounted price spectacles too but they lack various properties that improve your vision.
Surface coatings improve your vision quality and lenses durability. Hard coating enables plastic lenses to endure scratches better. Antireflection coating decreases the glare of the glass surface and reflections that tire the eyes. It also adds to the light strength of the spectacle lenses i.e. eyes get a clearer image of the object. The smudge-resistant surface helps to keep the lenses clean as soil and smudges do not leave traces so easily so you see more clearly.
If you see well into the far distance, you are long-sighted. A young long- sighted person sees as well at a near distance. If reading is hard and the text seems hazy, the reason may be weariness of the eye lens (also at a younger age) caused by near vision work or weakening of the eyes adaptability generated by ageing. In this case you need spectacles for near vision.
If you do not see far into the distance, e.g. cannot see clearly traffic signs or bus numbers, then you are short-sighted. You need spectacles for distance vision.
You need multifocal spectacles if your eyes need optical correction of diferent strength to see at a closer or farther distance. Multifocal eyeglasses are useful if you need spectacles for reading but your work sometimes requires you to look into distance without taking the spectacles off.
More about spectacle lenses
Eye flexibility deteriorates with age, you notice it when reading or doing some work requiring precision – you do not see so well when becoming older. If you move the book farther away, the text becomes clear again. In this case you need special spectacles for near vision work and during the eye examination a necessary close add will be determined.
A good solution for short-sightedness is monofocal spectacle lenses which give a good vision range. Monofocal glasses are a good choice when there is a lot of work and reading and this always happens at the more or less the same distance.The strength of the spectacles is always prescribed according to the individual needs of your eyes and working distance.
Common spectacles (bi- or multi focal) are suitable for reading, however their near vision area is smaller than that of monofocal spectacles.
Special work or office spectacles enable to have a sharp vision of several closer distances. They are made considering your necessary work distances and the spectacle lenses are ground to your individual strength.
The reason for neck and head pain is often wrong spectacles or false correction of eyesight! Make sure your work glasses are the best possible!
Good spectacle lenses are optically precise with no distortions when looking through them.
The choice of spectacle lenses material is important for different strengths: it is better to make lenses of greater strengths from thinned material to avoid accumulation of too much weight on the nose. The optical strength of the lenses is determined according to the purpose of the spectacles usage.
Monofocal spectacle lenses have the same strength all over the whole lens as e.g. in the so called 'common glasses' with which you see either far or near. The vision range i.e. how far or near you can see is affected by the lenses strength, adaptability of the user's eyes and eye lenses elasticity – called accomodation.
Spectacles meant for near range may be monofocal (in this case one sees the closer area determined by their strength and the user's eye adaptability), bi- or multi focal.
Bifocal spectacles have two different strengths – through the upper part of the lenses you see farther and the 'slot' in the lower part is for reading where the close add, i.e.suitable strength for reading, is inserted fitting your eyes needs.
The close add for multifocal spectacles is designed with smooth transition, i.e. the lenses have a different strength for reading, but the border between the areas is not visible.
Eyesight correction has to be the best possible in traffic for your own and others' safety's sake, so that you see road signs and other traffic participants at the right time. Check the strength of your driving glasses regularly. You may often need spectacles of a different strength for night driving. Make sure the frame is strong and fits well. For safety's sake it is good to have a reserve pair of spectacles.
Being blinded can be avoided by using protective sunglasses.The shade of photochromic lenses changes according to UV-radiation – but the darkening will not occur in a car as the window shields do not let the UV- radiation through. Polaroid lenses help to avoid the reflections from water or road surface.
UV-protection means that the spectacle lens does not let the ultraviolet (i.e. under 400 nm of the visible light) radiation to permeate. UV- protection is necessary to avoid the harmful effect of ultraviolet radiation. The damaging UV-radiation for eyes is reflected in an especially big amount from the snow or water surface in a sunshine weather.
Sunlight contains much UV-radiation, so you have to especially protect your eyes with sunglasses when moving on the snow or water. Bright light blinds you and disturbs your vision. Excessive UV-radiation may quicken the appearance of cataract.
Various multifocal lenses have areas of far and near vision (i.e. the upper and lower part) which are ground according to different eyes needs. Distortions caused by the lens structure appear on the edge area of multifocal lenses. Precise optical grinding enables to shift the location of the distortion, thus enlargening the area of either far or near vision. Large near vision area is good for work at a closer distance. However, if it is more important to see far into the distance, then it is advisable to choose the lenses with a larger far vision area.
The strength of multifocal lenses changes smoothly from the upper to the lower part with the greatest closer strength. The transition area can be used for intermediate vision (e.g. 1-2 m). The main difference between multifocal lenses is how wide or long the transition area is and how well one can use its strengths for seeing.
Narrow and small frames need specially designed multifocal lenses which are ground so that the lower reading area is large enough.