Glossary / lexicon
In our lexicon we explain to you the professional expressions of the ophthalmic medical science from A to Z.
Simply click on the corresponding letters.
Accommodative
The capability of the eye to focus directly both on close and distant objects without any assistance. The reduction of this capability as from the 45th year of age is known as age-related presbyopia: the person in question then requires reading spectacles.
Accommodative intraocular lenses
New innovative intraocular lenses with the target of restoring the accommodation of the eye. Accommodative intraocular lenses (e.g. 1 CU intraocular lens) can be implanted in the eye within the framework of a cataract operation
Ametropia (= refractive error)
Deviation from normal sight: short-sightedness (myopia), far sightedness (hyperopia) and corneal astigmatism.
Astigmatism
A sight deterioration caused by irregularities of the cornea, whereby instead of seeing individual points of an object, bars or stripes are seen.
Cataract
Opacity of the lens as a result of the natural aging process, pharmaceuticals or eye injuries.
Ciliary muscle
Muscle of the ciliary, which affects the accommodation (capability of the eye to focus sharply on close-up and distant objects). Through tightening, the zonula fibres are relieved, whereby the young lens is bent to a greater extent and thus develops stronger optical power.
Concave
A lens which is flatter in the centre than at the edge (diverging lens) is known as a concave lens. Concave spectacle lenses (minus lenses) are used for short sightedness.
Convex
A lens which is thicker in the centre than at the edge (converging lens) is known as a convex lens. Convex spectacle lenses (plus lenses) are used for far sightedness and age-related presbyobia.
Cornea
This forms the forward clear transparent part of the exterior eye skin. Its diameter amounts to approximately 11 to 12 mm, and its thickness in the centre to between 0.5 and 0.6 mm.
Dioptre
Measurement unit of the refracting power; if the eye is short sighted, a minus sign is shown before the value of the spectacle lens or the contact lens.
The refracting power of the lens is indicated in the dioptre unit (in short D). The dioptre figure indicates the reverse value of the focus measured in metres. A lens with 4.0 dioptre thus has a focus of 0.25 m.
