Glossary

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TermDefinition 
 
Bi-ToricLens design where both the anterior and posterior surface of the lens is of a toric construction. See also Toric Lens. View
BlendingThe process of merging the transition zones between two radii. View
BufferBuffers resist unwanted changes in pH and in the process help prevent deterioration. View
Bullous KeratopathyA degenerative condition in which small vesicles form in the cornea due to endothelial dysfunction. This condition can cause severe pain when the vesicles burst. View
Bull’s Eye Topography An orthokeratology shaping design where central corneal flatting is seen. See also Topography.View
Burton LampAn ultraviolet (blue) light source used in evaluating a fluorescein pattern . The Burton Lamp has its highest emission in the 300nm to 400nm range.View
Butyl Styrene PolymerPolymer used in the manufacturing of button materials for rigid contact lenses.View
CarrierThe portion of a lenticulated lens surrounding the front optic zone. The carrier portion can be plano, negative or positive in shape. Manipulating the carrier is instrumental in lid attachment techniques. View
Cast MoldingA contact lens manufacturing process where a liquid polymer is injected into a two-part mold. The parts are then pressed together to form a previously determined lens power, diameter, curvature and edge. The lens is then cured into a solid state.View
Cellulose Acetate Butyrate (CAB)Polymer used in the manufacturing of button materials for rigid contact lenses.View
Central Island Topography An orthokeratology shaping design where areas of steepness are seen in the central cornea. See also Topography. View
Chelating Agents Chelation is the presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central atom. The purpose of chelating agents is to bind to metal ions so they can easily be removed. View
Chromatic AberrationAn unequal refraction or focalization of light rays of different wavelength, resulting in a blurred image with fringes of color. See also Aberration. View
Coloring AgentsA naturally occurring or synthetically created substance added to another product in order to change its physical pigment.View
Compound Astigmatism Ocular astigmatism where both meridians are either myopic or hyperopic. See also Astigmatism.View
Concentric Multifocal Contact LensesThis design has concentric rings of power to accommodate different focal lengths. A bull's eye pattern enables alternating zones of strength from near to far. When a similar design is given in both eyes, depth perception is preserved as the patient is truly binocular. The arrangement is generally near center and distance periphery, but modifications of the design are commonly used. Alternating distance for near or modified monovision are other fitting techniques. View
Continuous WearThe use of contact lenses without removal. These designs allow for longer wearing periods of up to 30 consecutive nights.View
Conventional WearThe use of contact lenses in a non-disposable manner. These lenses can last up to one year.View
Corneal ApexThe tip of the corneaView
Corneal AstigmatismCondition where the shape of the cornea results in light rays that focus at more than one point on the retina. See also Astigmatism.View