C
Center thickness
Related to the term – contact lens transmissibility (Dk/t) The Dk value determines the properties of a contact lens material. A contactologist has to take the thickness of the lens…
Chelation
Chelation is a form of contact lens care which is used to remove inorganic deposits, particularly calcium and magnesium salts. The desired effect is…
Choroid
Choroid is the middle layer of the eyeball, which is composed of three structurally and functionally distinct tissues. It is part of the…
Ciliary body
The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The ciliary body is part…
Coloboma of the iris
Coloboma of the iris is a congenital defect of the uvea. The iris has an irregular shape, such as that of a keyhole or a teardrop. If only the iris is affected, then vision is not affected. If the…
Conjunction
Convex lens (clutch) is used for correction of farsightedness. It changes the parallel beam to the convergent beam…
Conjunctiva
The conjunctiva is a thin, transparent mucous membrane that covers the white part of the visible eyeball. It is very important when comes to…
Conjunctival hyperemia
This is a conjunctival vasodilatation of the vessel. It is caused by the release of histamine, often due to irritation of the conjunctiva. Vasodilation then causes swelling of conjunctiva…
Contactology
This is a branch of science that deals with the application of contact lenses. It is a combination of the studies of optics, geometry, biology, physiology, ophthalmology and psychology. No photo-…
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. The cornea, with the anterior chamber and lens, refracts light, with the cornea accounting…
Corneal contact lenses
These are contact lenses with diameter of 8.5 to 9.5 mm. They are produced as hard contact lenses, either from PMMA, or a copolymer of methyl methacrylate…
Corneal dystrophy
This is an inherited disease of the cornea. Cause of dystrophy is decreased adhesion of the corneal epithelium to the base membrane. The patient repeatedly wakes up with severe stinging…
Corneal erosion
It is a disease often linked to the trauma (irritation) of the cornea – caused for example by plants, needles, nails, damaged contact lens, deposits, etc…
Corneal permeability
Corneal permeability is very important in the application of eye medication because it affects its concentration. Acidic substances and non-dissociated substances penetrate through…
Corneal ulcer
Corneal ulcer, or ulcerative keratitis, is an inflammatory or more seriously, infective condition of the cornea involving disruption of its epithelial layer with involvement of the corneal stroma…
Correction
Removal or mitigation of a defect or disorder. Correction is a term used in the context of the treatment process – e.g. the correction of refractive defects with the use of glasses,
Cosmetic contact lenses
These contact lenses are used to either highlight or change the colour of the iris of a healthy eye. Those that aim to achieve dramatic expression or major change of image are sometimes called…
Curvature of contact lenses
After the optical power, this is the second most important factor for the selection of contact lenses. On the package you will find under the brand BC with given…