Glossary

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TermDefinition 
 
FlarePeripheral light scatter often experienced by rigid contact lens wearers.View
Flat “K” The meridian of the cornea that has the longer radius of curvature.View
Flexible WearThe use of contact lenses intermittently for daily and overnight use.View
FlexureThe bending of a contact lens in an effort to conform to the corneal shape. The amount of flexure is dependent on various factors including lens thickness and flexibility.View
FluoresceinSee also Fluorescein Sodium. View
Fluorescein Pattern The appearance of the tear film distribution, as viewed with fluorescent dye, between the posterior surface of a rigid contact lens and the anterior corneal surface.View
Fluorescein SodiumThe sodium salt of fluorescein used as a diagnostic tool to evaluate corneal or conjunctival epithelium, examine rigid gas permeable contact lenses and assess the tear film.View
Fluorosilicone AcrylatePolymer used in the manufacturing of button materials for rigid contact lenses.View
Fluorosiloxanyl StyrenePolymer used in the manufacturing of button materials for rigid contact lenses.View
Frequent ReplacementContact lenses designed for replacement at predetermined intervals. Intervals are usually monthly, quarterly or bi-annually. View
Front Optic Zone Diameter (FOZD)Diameter of the central front optic zone measured by the surrounding junction.View
Front Surface ToricLens design where part or the entire anterior surface of the lens is of a toric construction. See also Toric Lens. View
Ghost VesselsIntracorneal blood vessels which no longer carry blood.View
Herpetic keratitisA presentation of dendritic ulcers associated with the herpes simplex virus (HSV). View
HydrogelA hydrophilic polymer.View
HydrophilicA substance that is attracted to, and dissolves well within, water. These substances are referred to as “water loving”.View
HydrophobicA substance repelled by water. These substances are referred to as “water hating”.View
Hypercapnea A condition of excessive carbon dioxide (CO2) in the blood. View
HyperopiaOften called farsightedness, this is a condition where the eye is underpowered. Hyperopia causes rays of light to focus at a point behind the retina. Correction is achieved using “plus” or “positive” powered lenses.View
HypoxiaA condition where the body is deprived of oxygen.View