Glossary

  Search

Displaying 101-120 of 165 results.
TermDefinition 
 
Modified MonovisionA fitting technique used to address presbyopia. A patient is given a multifocal lens on one eye and a single vision lens on the other.View
MonovisionA fitting technique used to address presbyopia. A patient is given one single vision lens for distance and one single vision lens for near. Determining a patient’s dominant eye is often required.View
Mucin BallsTiny translucent spheres of cellular debris that develops under a contact lens. View
Multipurpose SolutionA contact lens solution that serves many functions. These products are often used for cleaning, disinfecting, soaking, wetting and storage.View
MyopiaOften called nearsightedness, this is a condition where the eye is over powered. Myopia causes rays of light to focus at a point in front of the retina. Correction is achieved using “minus” or “negative” powered lenses.View
NeovascularizationThe development of tiny, abnormal, blood vessels with the corneal stroma.View
Optic Zone DiameterDiameter of the central front or back optic zone measured by the surrounding junction.View
Ortho-KSee also Orthokeratology.View
OrthokeratologyOrthokeratology is the use of a specially designed rigid gas permeable contact lens, normally worn only at night, to improve vision through the reshaping of the cornea. Reshaping is enabled by using base curves flatter than the flat corneal curvature, reverse zones of steeper radii, and alignment zones for lens positioning.View
Osmolarity Agents Osmolarity agents adjust the composition of the formulation to the desired isotonic range. If the solution is "isotonic", the water concentration is the same on either side, and there is no net movement of water.View
Over-RefractionA refraction done over a prescription to determine if that prescription is over- or undercorrected.View
Overwear SyndromePainful corneal edema that develops due to endothelial cell changes. This condition is a result of a reduced oxygen supply secondary to excessive contact lens use. View
Oxygen PermeabilityThe rate of diffusion of oxygen through the contact lens material. View
Oxygen TransmissibilityThe value of oxygen permeability divided by the thickness of the contact lens material used.View
PachymetryA measurement of corneal thickness.View
Pellucid Marginal DegenerationA bilateral corneal thinning disorder. Unlike in keratoconus, the areas of thinning and protrusion are not the same. The corneal protrusion occurs in the area of the cornea that is above the area of thinning. View
Peripheral ZoneThe front or back region surrounding the central optic zone.View
Photo-Refractive KeratectomySee also PRK. View
Piggy Back LensA fitting technique that uses a combination of rigid gas permeable contact lenses above a soft contact lens.View
PMMAA transparent thermoplastic material that was the primary rigid contact lens material prior to gas permeable materials. These lenses fall under the category of “Hard” contact lenses.View