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a lens with segments providing two or more powers; commonly, a trifocal lens.
mul·ti·fo·cal lens(mŭl'tē-fō'kăl lenz)
A lens with segments providing two or more powers; commonly, a trifocal lens.
lens(lenz) [L. lens, lentil]
1. A transparent refracting medium, usually made of plastic.
2. The crystalline lens of the eye.
accommodating intraocular lens
A flexible intraocular lens inserted into the eye during cataract surgery. When tugged upon by the ciliary muscle, this lens can alter its shape to focus on objects that are near, far, or middle distances from the eye.
A lens that transmits light without separating it into the colors of the visual spectrum.
anterior chamber intraocular lensAbbreviation: ACIOL
An artificial lens placed in the anterior chamber on top of the iris after natural lens has been removed. The lens may be fixated to the iris or positioned in the anterior chamber angle.See: intraocular lens
A lens that corrects spherical aberrations.
A lens that corrects both spherical and chromatic aberrations.
A lens placed on the cornea to protect it while it heals, e.g., after a corneal abrasion or keratoplasty.
A lens that has a concave surface on each side.See: biconcave for illus
A lens that has a convex surface on each side.See: biconcave for illus
bifocal lensSee: bifocal eyeglasses
bifocal contact lens
A contact lens that contains two corrections in the same lens.
A lens that has a toric shape on both sides, used to correct astigmatism.
concave spherical lens
A lens formed of prisms with their apices together (thin at the center and thick at the edge), used for correcting myopia.
A lens made of various materials, either rigid or flexible, that fits over the cornea or part of the cornea to supplement or alter the refractive ability of the cornea or the lens of the eye. Contact lenses of any type require special care with respect to storage when they are not being worn, directions for insertion and removal, and the length of time they can be worn. The manufacturer's or dispensing health care worker's instructions should be read and followed. Failure to do this may result in serious eye diseases. Wearing contact lenses while swimming is inadvisable.
convergent lensPlus lens.
A lens that has a convex surface on one side and a concave surface on the opposite side.
convex spherical lens
A lens formed of prisms with their bases together (thick at the center and thin at the edge), used for correcting hyperopia.
corneal contact lens
A type of contact lens that adheres to and covers only the cornea.
A transparent colorless biconvex structure in the eye, enclosed in a capsule, and held in place just behind the pupil by the suspensory ligament. It consists principally of lens fibers that at the periphery are soft, forming the cortex lentis, and in the center of harder consistency, forming the nucleus lentis. Beneath the capsule on the anterior surface is a thin layer of cells, the lens epithelium. The shape is changed by the ciliary muscle to focus light rays on the retina.
A segment of a cylinder parallel to its axis, used in correcting astigmatism.
disposable contact lens
A soft contact lens worn for a week or two and then discarded.
divergent lensMinus lens.
extended wear contact lens
A contact lens made of materials that permit permeation of gas (such as oxygen) so that there is less chance for corneal irritation.
gas-permeable lensAbbreviation: GP lens
A contact lens that allows oxygen to pass through it, enhancing eye health, lens durability, and comfort. Gas permeability derives from the incorporation of silicone in lens plastic. GP lenses are used to manage visual conditions such as astigmatism, keratoconus, and presbyopia. Synonym: rigid gas-permeable lens
gonio lensGonioscopy lens.
A lens with one or more tilted mirrors that is applied to the cornea for use in visualizing the anterior chamber of the eye during gonioscopy.Synonym: gonio lens
hard contact lens
A contact lens made of rigid translucent materials.
A lens material that refracts more light than standard lens materials do. It is used to minimize lens thickness and weight.
hydrophilic lensSoft contact lens
implantable collamer lensAbbreviation: ICL
An artificial lens that can be inserted between the cornea and a patient's own lens, used to correct severe nearsightedness.
implanted lensIntraocular lens.
intraocular lensAbbreviation: IOL
An artificial lens made of acrylic, polymethymethacrylate, or silicone. The lens may be placed posterior to the iris (PCIOL) or anterior to the iris (ACIOL). Posterior chamber lens may be monofocal or multifocal and can also correct an astigmatic error. A lens is removed because of abnormalities such as cataracts. If the original lens capsule is present and an IOL is placed inside it, the surgical procedure is called posterior chamber IOL implantation. If the capsule has been removed in a previous surgical procedure, the IOL may be placed in front of the iris, directly adjacent to the cornea. This is called anterior chamber IOL implantation. In another procedure, the IOL is implanted behind the iris. Which method of IOL implantation produces the best results is being investigated.Synonym: implanted lens See: cataract
A concave lens used to improve visual acuity in myopic patients.Synonym: divergent lens
monofocal intraocular lens
An intraocular lens inserted by the ophthalmologist during cataract surgery that allows the wearer to see clearly at a single distance (close to the eye, far from it, or in intermediate focal points). Monofocal lenses were the only lenses used in the first few decades of cataract surgery.See: multifocal intraocular lens
multifocal intraocular lens
An intraocular lens inserted into the eye during cataract surgery that gives the wearer clear vision at near, intermediate, and far focal points.See: monofocal intraocular lens
multifocal lensProgressive lens.
oil immersion lens
A special lens with oil placed between the lens and the object being visualized. This eliminates a layer of air between the microscope slide and the lens, producing a clearer image than if the oil were not used.
A lens that produces no distortion of the periphery of the image.
A combination of a hard contact lens placed over a soft contact lens, used to treat two different ocular conditions.
A convex lens used to improve visual acuity in hyperopic patients.Synonym: convergent lens
rigid gas-permeable lensGas-permeable lens.
posterior chamber intraocular lensAbbreviation: PCIOL
See: intraocular lens
An eyeglass lens, used to treat presbyopia, that gradually changes prescription strength from the top of the lens, for distance viewing, to the bottom of the lens, for seeing objects close-up. Progressive lenses enable the eyes to adjust from one distance to another (as when one looks up from a book) without the image jump associated with bifocals. Synonym: multifocal lens
silicone hydrogel contact lensAbbreviation: SH lens
A soft, extended-wear contact lens designed to improve the delivery of oxygen to the corneal epithelium. Depending on their design specifications, such lenses may be worn 6 to 30 days and nights consecutively.
soft contact lens
A contact lens made of flexible, translucent materials. Such lenses are more comfortable, can be worn longer, and are harder to displace than hard lenses, but there are disadvantages. They may not provide the same degree of visual acuity as hard lenses, and they require more cleaning and disinfection. Production of tears may be decreased, esp. in older patients. The soft lenses may need to be replaced every 6 to 18 months. Corneal infections can prevent further use of soft lenses and also cause permanent loss of vision. Synonym: hydrophilic lens
A lens in which all surfaces are spherical.
toric contact lens
A contact lens with two separate curvatures, used to correct astigmatism and distance vision simultaneously.
A lens used in testing the vision.
A corrective eyeglass lens containing three segments for near, intermediate, and distant vision.
A type of lens that can be adjusted to focus on near or distant objects.