NCLE Vocabulary Flashcards
Adjustment by the eye for seeing at different distances, accomplished by changing the shape of the crystalline lens through action of the ciliary muscle.
Clearness; visual acuity is measured by the smallest object that can be seen at a certain distance.
Accessory structures of the eye, such as the lacrimal apparatus and the eyelids.
Image of an object that persists when the lids are closed.
Annular Bifocal Contact
A lens with distance portion ground into the center of the lens and the near portion ground into the periphery.
Lenses designed for post cataract fitting.
Apical Zone of Cornea
The central portion of the cornea with a constant radius of curvature. Also called the corneal cap.
Wetting agent for the cornea to supplement the loss of tear formation.
A lens which is not spherical in shape. The curvature gradually flattens as the periphery is approached.
A refractive error that prevents the light rays from coming to a single focus on the retina because of different degrees of refraction in the various meridians of the eye.
A condition in which the steepest corneal meridian is in the horizontal plane. An example of Keratometer readings for a patient exhibiting against-the-rule astigmatism would be: K’s 45.00@180/42.00@90.
Astigmatism caused by an irregularly shaped cornea. This can occur in conditions such as Keratoconus or corneal scarring. This type of astigmatism cannot be corrected by cylinders.
Astigmatism that is found in the crystalline lens.
Regular astigmatism in which the principle meridians are other than 90 and 180.
Astigmatism remaining after the corneal astigmatism has been neutralized.
Condition in which the steepest corneal meridian is in the vertical plane. An example of Keratometer readings for a patient exhibiting with-the- rule astigmatism would be: K’s 42.00@180/45.00@90.
A chemical that disinfects and kills pathogenic organisms.
A preservative used in contact lens solutions because of its germicidal qualities.
A method of examining the cornea under a magnification of from 10 to 50 times utilizing a slit lamp.
An ultraviolet light used to illuminate the fluorescein dye that is used to analyze the fit of a rigid contact lens.
The angle at either end of the slit between the eyelids; specified as outer (temporal) and inner (nasal).
The straight line measurement of the contact lens diameter from edge to edge.
Contact Lens Wetting Angle
The angle between the liquid and the lens surface.
A tricurve lens designed to conform to the curvature of the cornea, which flattens as it extends in the periphery.
Two or more chemicals that are combined to form a new chemical compound.
The apical zone or central zone of the cornea that has a constant area of curvature.
The diameter of the cornea, usually taken along the horizontal meridian with a ruler. Also called visible iris diameter.
The state of relative dehydration maintained by the normal intact cornea that enables it to remain transparent.
Diagnostic Fitting Set
A set of trial lenses used to gain an overview of the fit of a contact lens.
Physical or chemical procedures that kill common pathogenic organisms but may permit some nonpathogenic organisms to survive.
A measure of the oxygen permeability through a given material where D is the diffusion coefficient for oxygen movement on the lens material and K is the solubility of oxygen in this material.
Double Slab-Off Lenses
Sometimes called thick-thin lenses; the upper and lower portions of the lens are reduced in thickness so that when the lens is placed on the eye these portions lie under the upper and lower eyelids. The thin zones aid in stabilizing toric soft lenses.
Areas of drying as noted by absent areas of fluorescein-stained tear film on the cornea when the patient stares.
Dyer Nomogram System of Lens Ordering
A simplified system of ordering rigid lenses based on clinical experience, corneal topogometry, and charts of associated lens parameters.
A cleaning agent that acts on a soft lens by a digestion of protein.
A device used to evaluate corneal sensitivity, consisting essentially of a nylon thread mounted in a handle so that its length may be varied and calibrated in milligrams of weight necessary to bend a given length of the thread when pressed against the cornea.
Elliptic space between the eyelids.
A complete lens with anterior and posterior curves, a specified diameter, a designated peripheral curve, and edge design.
A complete inventory of lenses of graduated powers and base curves.
Flutterings or fringing of lights caused by a lens with an optic zone too small as a decentered lens or an excessively loose lens.
A cornea with a K value less than 41.00 D.
Power created by having a very convex or concave tear film.
An organic compound that is inert and used to stain the tear film for contact lens fitting and to assess the integrity of the cornea.
The part of a contact or intraocular lens that supports the optic portion and touches the peripheral or nonoptic portion of the cornea: the word indicates “fastening, contact, sense of touch.”
A bactericide used for soft lenses.
A corneal transplant.
Relatively large lens most suitable for large, flat eyes; consists of a central optic zone and a surrounding nonoptic flange.
Junction between the periphery of the cornea with the sclera.
A contact lens with excessive movement; it can be caused by a lens that is too small in diameter, too thick or too flat.
Sebaceous glands of the eyelid.
A lens less than 0.10 mm in thickness.
A lens designed with an edge configuration similar to that of a minus lens that is thicker at its periphery; often used with high-plus lenses such as aphakic lenses.
Single-vision contact lenses used for presbyopes for whom the power of the lenses is such that one eye is used for distance vision and the other is used for near vision.
A drug that causes the pupil to contract.
A table of precalculated mathematical values used to arrive at the specifications of a rigid lens design.
The technique of flattening the cornea and thus correcting refractive errors by the use of a series of progressively flatter contact lenses.
A measure of the amount of oxygen that will pass through a given area of material in a given unit of time.
The degree to which a lens permits the passage of oxygen across it. It depends on the composition of the plastic (that is, silicone has excellent permeability, whereas PMMA has no permeability), the thickness of the lens, and its water content. It is often expressed as the DK value.
An instrument used to measure the thickness of the cornea and depth of the anterior chamber.
An instrument designed to photograph annular rings of the cornea and to aid in making a contact lens that will contour to the cornea.
A disc with concentric rings to determine the regularity of the cornea when its reflection is revealed on the corneal surface.
A lens with zero power.
A chain of linked molecular unity of dimension greater than 5 monomer unity.
The union of molecules of a compound to form larger molecules and a new compound.
A wetting agent.
Prism Ballast Lens
Contact lens with base-down prism added inferiorly to improve the stability of the lens. Usually 1 to 1.5 D of prism is added.
A surgical procedure in which clock like incisions are made into the cornea to flatten the cornea and correct myopic refractive errors.
The astigmatism present after the corneal astigmatism has been nullified by a contact lens.
Light is focused on deeper structures such as the iris, while the microscope is adjusted to study the cornea.
Measures normal tear secretion; the ability of the eye to wet in 5 minutes 15 mm of a 5 x 35 mm strip of filter paper.
A contact lens blank in which the posterior curve of the contact lens has been fabricated.
A solution designed to keep a lens moist and free from contamination.
A rigid lens designed by Joseph Soper with a steep central posterior curve to accommodate large cones of keratoconus.
A reflection from a mirror surface, such as the back of the cornea.
It is the spheric power of the lens plus half the cylindric power.
A method to ensure the complete death of all forms of bacteria fungi, and spores.
A cleanser that acts on the surface of a contact lens.
Tear Film Breakup Time (BUT)
An evaluation of tear quality; the tear film will normally break up in 10 to 30 seconds and show dry spots. Any dry spot that appears in less than 10 seconds is pathologic.
Disinfection of a lens by heat.
Thickness of a Lens
The measurement of the center of the lens.
A mercurial agent used for disinfection.
That area of the cornea between the apical zone and the limbal zone.
A design feature used in toric lenses to reduce lens rotation by cutting off a peripheral portion of the lens to conform with the lower lid border.
A ruler measure with a groove to measure the diameter of rigid lens.
Visible Iris Diameter (VID)
A term that represents the iris diameter and aids in selecting the initial lens; often used in place of the corneal diameter.
A permanent bending of a rigid lens. May also refer to a semipermanent altering of the corneal curvature.
The use of soaking solution to store rigid contact lenses.
Solutions that increase the spreading or wettability of liquids in the plastic contact lens by converting the surface of a lens from a hydrophobic to a hydrophilic surface.