The part of a prescription that indicates the correction needed for an astigmatism.


The specific lens prescription power required by a patient to render the best vision possible.


Transparent portion of eye in front of the iris (colored part).


The movement of the eyes in such a way that the internal recti turn the visual axes to intersect at some finite point.

Contact Lens Evaluation, Fitting, and Follow-Up Care (CLEFFU)

If you wear or want contacts, you need a contact lens exam in addition to a comprehensive eye exam. Your eye doctor will perform special tests during a contact lens exam to evaluate your vision with contacts. The first test will measure your eye surface to determine what size and type of contacts are best for you. Your doctor may also do a tear film evaluation to make sure you have enough tears to comfortably wear contacts.

With the results of those tests, your eye doctor can provide a contact lens prescription that is the right fit for your eyes. An eyeglass prescription is no substitute for a contact lens exam because the two are very different. An eyeglass prescription measures for lenses that are positioned approximately 12 millimeters from your eyes; whereas a contact lens prescription measures for lenses that sit directly on the surface the eye. An improper fitting or prescription of contacts can damage the health of the eyes. Once you have the correct fit and prescription for contacts, you’ll need to decide whether you want disposable contacts or extended wear, and if you want your contacts to be colored.

Your doctor will fit you with a trial pair of contacts and have you wear them for a few days. In about a week, you’ll need a follow-up exam to make sure you have adjusted to your new lenses. Whether you wear glasses or contacts, it’s a good idea to get a yearly eye exam to see if you have new or existing vision problems, and if you need vision correction.

Contact Lens

A small shell-like lens that rests directly on the eye. There are many styles:

  • Soft lens: Lenses made from flexible water- absorbent plastics. These lenses are comfortable, even at the end of the day.
  • Daily-wear: Lenses put in the eye at the beginning of the day and removed at the end of the day.
  • Disposable/planned-replacement: Soft lenses that are worn for a prescribed length of time, then are discarded. Compared to conventional soft lenses, these lenses offer the patient better eye health, clearer vision, increased comfort and a fresh-lens feeling on a continuous basis. There is very little to no maintenance involved with these lenses.
  • Extended-wear: A soft lens with the same comfort as a daily-wear soft lens, but that can be left in the eye for up to two weeks. Also tears easily.
  • Gas-permeable: A hard lens that is very oxygen- soluble and quite comfortable to wear. They need minimal care and last for years.
  • Hard: One of the first contact lenses. Made of hard plastic. Generally not as comfortable as soft or gas- permeable lenses.
  • Monovision: A contact lens fitting technique used to correct presbyopia. The dominant eye is used for distance vision, while the weaker eye is used to see close up.
  • Scleral shell: A contact lens that fits over both the cornea and the surrounding sclera (i.e., the white of the eye).
  • Standard: Single-vision spherical lenses (can be planned replacement, disposable).
  • Specialty: Includes but is not limited to, toric, multifocal and gas permeable lenses.
  • Toric: A contact lens of a specific design to correct astigmatism. Toric lenses may be made of soft or rigid materials. They are curved in a way that compensates for the irregularly shaped cornea.
  • Visually required: Contact lenses prescribed for conditions in which visual acuity cannot be adequately

Computer Vision Syndrome (CVS)

Eye strain, blurred vision, headaches and other symptoms caused by prolonged computer use.

Comprehensive Eye Examination

It describes a level of service in which a general evaluation of the complete visual system is made. The comprehensive services constitute a single-service entity but need not be performed at one session. The service includes history, general medical observation, external and ophthalmoscopic examination, gross visual fields and basic sensorimotor examination. It often includes, as indicated, biomicroscopy, examination with cycloplegia or mydriasis and tonometry. It always includes initiation of a diagnostic and treatment program as indicated.

Color Blindness

Reduced ability to distinguish between colors especially shades of red and green inherited trait passed down from mothers to sons.


A partial or complete loss of transparency of the crystalline lens. The clouded lens is removed by surgery and usually replaced with a plastic lens called an intraocular lens implant.


The part of the frame that rests on the nose and joins the two lenses.

Blue Light-filtering Glasses

Have filters in their lenses that block or absorb blue light, and in some cases UV light, from getting through. That means if you use these glasses when looking at a screen, especially after dark, they can help reduce exposure to blue light waves that can keep you awake.

Blended Invisible Bifocal/Blended-segment Lenses

A lens containing two different powers, one for distance vision and one for near vision. The segment with near-vision prescription is invisible.


A lens containing two different powers: one for distance vision and one for near vision.


An improvement process in which an organization measures its performance against that of best-in-class organizations, determines how those organizations achieved their performance levels, and uses the information to improve its own performance. The subjects that can be benchmarked include strategies, operation, processes and procedures. The objective of benchmarking is to identify and learn best practices and then to use those procedures to improve performance.

Base Curve

The front curve of any lens. The higher the base curve (8-12 base) the more curved the lens is, thus making the frame curved.


The part of a prescription that describes how the cylinder is oriented in the eyewire.


A condition of the cornea or crystalline lens in which light rays converge on two separate focal points.


A term used in place of employees to refer to an organization’s work force. Associates refers to people working together toward a common goal.

Anti-reflective Coating, Non-glare (ARC)

Anti-reflective (AR) Coating reflects light off the lens surface, providing wearers with a reduction in glare and eye fatigue. Anti-Reflective coating is especially helpful when driving after dark and working on a computer. Anti-reflective Coating is typically sold under a variety of brand names. Anti-reflective categories include:

  • Standard tier
  • Reduces glare
  • Creates a better cosmetic appearance than ordinary lenses with no AR treatment
  • Premium tier
  • Reduces glare and reflections
  • Easier to clean, and more durable than standard AR lenses
  • Provides comprehensive UV protection
  • Ultra tier
  • Reduces glare and reflections
  • Easier to clean by having superior protection against smudges, oil, and water
  • Provides comprehensive UV protection
  • Ultimate tier
  • Exceptional visual clarity and protection against glare and reflections
  • Repels dust and dirt for clearer vision and less cleaning
  • Provides comprehensive UV protection
  • With Crizal and Viso Prevencia, patients will also receive protection from harmful blue light
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