Contact Lens Glossary, Vision Terms at ContactLenser.com
Contact Lens Glossary
Accommodation: The process of changing the shape of the lens to make it possible to see near and distant objects clearly.
Aspheric Multifocal: A non spherical lens with many focal points blended throughout the lens
Astigmatism: occurs due to the difference in curvature of the lens of the eye and as a result the eye focuses better in one plane than the other .
Atopy: An allergy associated with increased levels of immunoglobin E.
Best corrected vision acuity or BCVA: The best possible score one can attain on the acuity test with prescription glasses or lens.
Biconvex Lens: Two sides that are rounded, curved evenly and elevated.
Bifocal: Corrects both near and farsightedness with one optical instrument that has two distinct optical power.
Cataracts: A condition in which protein accumulates in the lens and clouds the vision. It can be corrected through surgical removal and a implantation of artificial lens.
Cornea: The transparent layer that extends over the front portion of the eye.
Cosmetic Lenses: non prescriptive lenses that are only used to change the color of the eye.
Daily use lenses: Contact lenses that must be removed prior to sleeping.
Enzymatic Solution: Used to remove proteins and antigen buildup on the lenses.
Extended Wear Lenses: Lenses that are prescribed to be worn up to thirty days continuously without being removed.
Eye care practitioner: Anyone in the healthcare system that works or deals with the eyes.
Farsightedness: Difficulty in seeing nearby objects clearly because the eyeball is too short and the image is formed behind the retina.
Hard lens: Rigid, but lack of breathability in its structure. The lens can be kept for a extended period of time of usually 3-6 months, but must be removed every night before sleeping.
Hydrogen Peroxide Solution: Used to disinfect the lenses to prevent common ocular infections.
Hypermetropia: Difficulty in seeing nearby objects clearly because the eyeball is too short and the image is formed behind the retina.
Iris: The portion of the eye that is colored.
Lens solution: A liquid that is used to rinse, disinfect and store contact lenses.
Lenticulated Multifocal: Lenses that have circular rings of different powers to accommodate different vision requirements.
Made to order (MTO) lenses: Lenses that are customized for patients who suffer from uncommon optical disorders.
Mixed astigmatism: A form of astigmatism in which one myofascial meridian is hyperopic and the other is myopic.
Monovision: patients of presbyopia are fitted with one lens for distance and one lens for near vision.
Multifocal Lens: occurs in more than one location; corrects both nearsightedness and farsightedness.
Multipurpose Solution: Liquid that has multipurpose in such that it cleans the lense, disinfects it and stores them to keep them hydrated.
Myopia: Difficulty seeing distant objects because the structure of the eye is too long or the cornea is too curved and the image of the object is formed in front of the retina.
Nearsightedness: Difficulty seeing distant objects because the structure of the eye is too long or the cornea is too curved and the image of the object is formed in front of the retina.
Ophthalmoscope: Instrument to view the interior of the eye.
Ophthalmoscopy: visual exam of the interior of the eye.
Opthamologist: Medical doctor who specializes in treating disorders of the eye .
Optic nerve: A nerve that carries impulses from the retina to the cerebral cortex.
Optical Power: The capacity of the lens to bend light rays.
Optometrist: A non medical professional who examines eyes to see if there are vision problems and prescribes lenses.
PMMA: Polymethyl Methacrylate or also known as Plexiglass is an alternate to glass. It is considered a hard lens.
Presbyopia: A defect in vision caused by a decrease in the elasticity of the ciliary muscle, which causes difficulty for the lens to accommodate nearby objects.
Refraction: Bending of light rays by the cornea, lens, and fluids in the eye to bring back the rays into focus on the retina.
Refractive Lenses: Custom fitted Rigid Gas Permeable lenses that reshape the cornea to correct small imperfections of nearsightedness and astigmatism.
RGP: A combination of soft and hard lenses that allows an increase oxygen intake to the cornea compared to hard lenses alone.
Saline Solution: Used to only rinse the lens, and clean them of any protein stuck on the lens.
Silicone: A polymer that has been used in manufacturing of contact lenses due to its ability to repel water and increase oxygen breathability.
Slit lamp Microscopy: Examines the anterior ocular structures under a microscopic magnification.
Soft lens: Lens that don't restrict the flow of oxygen to the cornea which increases its breathability. However due to less rigidity, it can accumulate foreign material in its porous structure and cause infection over extended continuous usage.
Spherical lens: The outer and inner portion of the optics resembles that of a sphere.
Strabismus: Defect in eye muscles so that both eyes cannot focus on the same point at the same time.
Toric lenses: Either one or both surfaces of the lens has the effect of a cylindrical lens used collectively with a spherical lens. They are more rigid and are made to last longer. They must be fitted precisely as the thickness of the lens varies.
Trifocal: A prescriptive lens that corrects three different lengths of Near, Arms length and Distant objects.
Uncorrected vision acuity or UCVA: The best possible score one can attain without any prescription or correction to their eyes.
Visual Acuity Test: A test that assesses the patients clarity of vision.
Visual Field Test: A measurement of an area which objects are seen when the eyes are fixed, looking straight without moving the head.
Weekly/bi weekly lenses: Soft Disposable lenses that must be replaced on either a weekly or biweekly basis to prevent infection.