You are unique – as is every other person. We all have our own personalities. Every eye has its own character, too – not a single one is identical with another one. Only a customised lens can meet these special requirements. The more precise the examination of your eye and your visual patterns by the optometrist is, the better your visual impression will be as you put on your new glasses.
What makes a lens unique? How much measuring data does it take to perfectly align the lens with your individual needs? And why will you enjoy more relaxed vision if you choose customised lenses?
Try this exercise: Cover half of your face with a mirror whilst standing in front of another mirror. Now your own face will look strange to you – unnatural, even. Not a single person on earth has two symmetric halves of a face. Even this minute detail plays a huge role in the micrometre precise production of lenses because the highly sensitive human eye does recognise even the tiniest deviations. The long term results could be visual problems or fatigue. It is therefore hardly surprising that your visual impression will be more comfortable and more relaxed if your lenses and frames are aligned accurately with your individual symmetry and the shape of your face.
It is even more important to obtain such precise data if your lens is highly complex or powerful. The highest discipline is the production of progressive lenses where the transitions of the long distance vision zone and the reading zone are cut into the lens invisibly. Customised production is of particular importance for these lenses so that the vision result attained is not hampered in the transition zone between remote and close-up vision.
Eye distance: Measurement of the distance between the right and left eye from the centre of the pupil to the bridge of the nose.
Personal vision patterns: Have you ever consciously thought about the way you read a book or at which distance you keep your tools or needles while working? These measurements are critical for the customisation of your personal lenses, as is your occupation (are you working at a desk or are you a craftsman who works outdoors a lot?). Another aspect to be considered is your hobbies.
Vision height of the eye: The point where your left and right eye looks through the lens is also different from eye to eye. It is measured from the bottom rim of the glasses, i.e. the rim of the frame.
Frontal incline of the frame: Given that every face has a different profile, the frontal incline of the glasses is different also. Consequently, it is very important that this value is also considered in the calculation of your individual lens requirements.
Distance between eye and lens: This distance also differs from individual to individual. Experts call it the back vertex distance. Compare, for instance, the facial profile of a European and an Asian. You will instantly recognise a difference with the naked eye.
Bending degree of the frame: To adjust the glasses to your face, the frame is slightly concave. Experts call this the degree of wrap. It also has to be included in the precise calculation of an individual lens.