Men and Women Eyeglasses and Spectacles
What does cylinder mean and what is prism Cylinder Often the refraction of the eye (cornea and lens together) is not equally strong in all directions. This is called astigmatism. The glass of the glasses must then correct more in one direction than in the other. One speaks – especially with contact lenses and implant …
Around the age of 40, the eye will slowly lose accommodation capacity because the lens of the eye becomes less flexible and cannot become convex enough to see nearby objects sharply. This is called presbyopia (old-sightedness). The bottom line is that the proximity point (see schematic image) will be further away. It is a normal …
Farsightedness or hyperopia / hypermetropia is an eye defect in which a person cannot see sharply without accommodation of the eye. Farsightedness is caused by a too short eye axis or too little strength of the refractive system of the eye (cornea plus lens), which creates the image of objects ‘behind the retina’. In order …
Short-sightedness or myopia is an ametropia in which the person (then called a myope) cannot see sharp objects far away, but nearby objects. Hence the name (close) myopia. Therefore, an object with a 0 vergence will not be sharply perceived and as the object approaches, the vergence will drop to a negative number. As soon …
The nearest point from which one can still see clearly without difficulty is called the proximity point. In a normal (emmetropic) human eye this point is about 30 cm in front of the eye; even closer at a young age. The most distant point from which one can still see sharply is called the vertepoint, …