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Eye Care ABC's



Aberrations are distortions of the images due to imperfection of the vision system.


Acetate or cellulose acetate is a plant-based plastic that is hypoallergenic. It is from a renewable resource, lightweight, non-brittle, and very strong.  Cellulose acetate is widely used today to make frames because it has a wide range for transparency, rich colors.


Accommodation is the ability for the eye to increase its focusing power to see clear when objects are at a near distance.

Add Power

This has to do with the “reading glasses”.   It is the number that specifies additional focus power you may need to see clear with near objects.  Add power is included in Bifocal and Progressive lenses.


Amblyopia is the medical term used when the vision in one eye is reduced because the eye and the brain are not working together properly.  It usually arises during childhood, the eye itself looks normal, but it is not being used normally because the brain is favoring the fellow eye. This condition is also sometimes called lazy eye.

Anti-reflective Coating

Multi-layer of thin films are put on top of the lens, to reduce the light bounces back from the surface.  The cosmetic benefits are not reflecting glare from your eye, and the scenery is brighter due to more light coming through the lens.

Arm/ Temple

The arm or the temple is the part of your glasses that runs alongside your head and rests on the ear.  It is essential to hold the frame in place correctly.


Astigmatism is a common optical condition which results in blurry vision. One way to see this that perfectly round shape eye, is like a basket ball, without astigmatism.  A football shape eye is not symmetric along both axes. That causes distortion of vision. This condition is easily correctable with proper prescription lenses.


This is an eye measurement machine that is often used to determine the baseline prescription of your glasses or the starting point.  It provides a rough prescription that requires final adjustment.  Hence those attempts using an autorefractor to prescribe glasses typically resulted in wrong Rx and headaches.


If you have astigmatism, the axis is the number on your prescription that determines the angle of your astigmatism correction (ranging from 0 to 180 degrees). The axis and cylinder values are always related.  Accurate axis measurement is critical to provide crisp vision.

Base Curve

The base curve is the amount of curvature on the front surface of a lens, mostly used in the specifications of a contact lens.  The larger base curve is for large eye shape.


BCVA or Best Corrected Visual Acuity is the best possible vision a person can be corrected for, with corrective lenses. It is measured in the line numbered in a Snellen chart, such as 20/20, 20/16, etc.


Bifocals are lenses containing two focal powers. They are usually are arranged with the focus for distant on the top and the near at the bottom portion of the lens. They are different from PALs in that they have a visible line demarking between the two focal regions.

Blink Reflex

The blink reflex, also known as the corneal reflex, is an involuntary blinking of the eyelids prompted by stimulation of the cornea. Such as touching or the introduction of a foreign body. It’s our body’s way of protecting the eye from any kind of foreign threat.

Cat-eye Glasses

It is a frame style, defined by having an upsweep at the outer edges where the temples or arms join the frame front, mimicking the shape of a cat’s eye.

American artist, Altina Schinasi, is credited with designing cat-eye shaped glasses. Schinasi’s glasses were so highly publicized by magazines like Vogue and Life that she decided to establish her own company to distribute them. In 1939, she received an American Design Award from Lord & Taylor for the flared-frame Harlequin glasses.

Color Blindness

Individuals with color blindness recognize colors differently from the way most of us do. Color blindness is very common, and the severity can range from mild to severe. People who are color blind are born with it. Typically, it is a genetic condition and is carried on the X chromosome, affecting more men than women. It is estimated that about 1 in 12 men and 1 in 200 women have some form of color blindness.


If you have astigmatism, this is 1 of 3 pieces of information that appears on your prescription. It refers to the lens power needed to correct for astigmatism power. If you have a cylinder, then it also has an axis value— you can’t have one without the other!


Eye care professionals will sometimes dilate your pupils during an exam to get a better look at your retina. Simply put, this means that your pupils will be expanded (or dilated), using special dilating eyedrops. If you’ve ever had your eyes dilated, you know that it can make your vision blurry and your eyes especially sensitive to light for a few hours until the pipul recovers from the eye drop. If you have to have your eyes dilated, you should consider bringing a designated driver! Driving isn’t recommended for several hours.


A diopter is a unit of measurement, like a centimeter or an inch. Instead of measuring distance, it measures the refractive or optical power of a lens. It is denoted as a “D” in your prescription.

Expiration Date

The expiration date is typical for 2 years.  Your vision may change over time.  It is to ensure you check your vision at least once every two years.

Eye Drops

Eye drops are any ophthalmic liquids that you apply to your eyeballs. There are many reasons you may need eye drops, itchy eyes, dry eyes, etc. Some drops are medicated to treat glaucoma, eye infections, and other conditions.


Eyes are the round/globe-shaped organs.  The eye is an important organ that gives us the sight.  Some eyes have good vision, while others require corrective devices, like glasses, contact lenses, or refractive surgery to correct their blurry vision.


Eyestrain is when your eyes become tired from too much eye activity.  Reading, looking at a computer screen, driving long distances may cause eyestrain.


Farsightedness, also known as hyperopia, is a common vision condition in which one can see objects in the distance clearly, but objects nearby will appear blurry.

Fitting of a Frame

How to tell if your frames fit right:

  • The frame should rest with equal weight on your ears and nose, gripping your temples (or sides of your head) lightly.
  • The width of the frame should be equal to the width of the face from ear to ear.
  • The bridge of the frame should be at the bridge of the nose.
  • Your frames should not slide down your nose
  • While smiling, your cheeks should not touch or push your frame

If you aren’t sure or if you think they don’t fit properly bring them into one of our store locations for adjustments.


A vision correction device.  Typically, a frame comes with lenses in them. They can be used for correct vision deficiency, or frames can be a fashion accessory.

High-index Lens

It is a lens made of special high index material.  It makes lenses thinner and lighter.  For people having high power corrections like over -4D, these lenses are more comfortable and more appealing, without the so-called  “coke-bottle” look.


Hydrophobic refers to lenses that repel water. All of our lenses are made with superhydrophobic coatings, which repel moisture to help reduce smudging.


See farsightedness.


The iris is the color part of your eye. The iris is like a light shutter on a camera, regulating the amount of light that enters through the pupil.


Yellow coloring in the skin and eyes caused by a variety of conditions involving the liver, gallbladder, and bile ducts, including hepatitis and cirrhosis.

Keyhole Bridge

A bridge is the piece of the frame that goes over your nose and connects the two lenses. A keyhole bridge looks like an old-fashioned keyhole. It has short nose pads resting on side of the nose, and avoids the bridge touching the nose, for more comfort.  It also gives a frame a little extra personality and a vintage look.

Low Bridge Fit

Low Bridge Fit frames are designed for those with low nose bridges. They are ideal for wide faces or people with high cheekbones. The bridge of the frames tends to sit in-line with your pupils or lower than traditional frames.


A circular corrective lens, surrounded by a wire ring around it. It is usually attached to a string or wire that attaches to the wearer’s clothes. Antiquarian Philipp von Stosch wore a monocle in Rome in the 1720s, in order to examine engravings more closely.


See nearsightedness.


People that are nearsighted have trouble seeing distant objects.  Another word for it is myopia. There are more people nearsighted than far-sighted.

Nose Bridge

Nose bridge refers to the part of the frame that connects the two lenses and sits in line with the pipuls of the eye.

Nose Pad

The pads that rest on the sides of your nose.  Together with the temples resting on the ears, it supports the frame in position and ensures the wearing is comfortable.


You may see this on your prescription. It is an abbreviation that stands for oculus dexter, in Latin which translates to “right eye”


An optician is an eye care professional who is trained to interpret, fit, and dispense prescription eyewear. They don’t provide you with the prescription itself. Think of them as the pharmacist of the eye care world.


Optometrists are eye care professionals who provide primary vision care ranging from sight testing and correction to the diagnosis, treatment, and management of eye conditions and vision changes.


An ophthalmologist is a medical doctor in eye care that diagnoses and treats all eye diseases, performs eye surgery and prescribes, and fits eyeglasses and contact lenses to correct vision problems. Some ophthalmologists are also involved in scientific research to discover the causes and cures for eye diseases and vision disorders.


You may see this on your prescription. It is an abbreviation that stands for oculus sinister, in Latin which translates to “left eye”.


A phoropter is an instrument that looks like a butterfly mask. Your doctor uses it for refraction during an eye examination to determine your prescription. You will be most likely asked, “Which is better? 1 or 2”?


Pince-nez means pinch-nose in French. This old-fashioned style of glasses is easily recognizable because the frames stay put on your face by pinching the nose. It does not have temples that go over your ears.


Plano means level or flat. For glasses, it refers to a lens that does not have any refractive power.

Polarized Lenses

Polarized lenses cut out reflective glares from objections in the sunlight.  It delivers superior clarity by filtering out those super bright lights.  People with extreme light sensitivity can really benefit from a polarized lens.


Polycarbonate eyeglass lenses are 10 times more impact-resistant than glass or regular plastic lenses. All of DigiVision Optical's lenses in our standard in our base package come with polycarbonate, not an upgrade as in other retailers.  Did you know that the polycarbonate material used for eyeglass lenses was developed by the aerospace industry for use in helmet visors worn by astronauts? If it’s good enough for the astronauts it’s good enough for us!


Presbyopia is a medical term for farsightedness that is caused by a loss of elasticity of the eye’s lens, typically occurs in middle to old aged patients. Apparently it happens to the best of us as we age. Don’t worry, you’ll just need reading glasses, bifocals or progressives lenses to correct it. Just another excuse to buy a cute pair of glasses if you ask us!


Some eyeglass prescriptions will contain only one number (the sphere) or more likely the case, they contain three numbers (sphere, cylinder, and axis). If you have three numbers, it means that you have astigmatism. The sphere indicates the strength of the lens you need. While the Cylinder indicates the lens power needed to correct your astigmatism. The axis indicates the angle to place the lens correction for astigmatism


Some people require a prism for their prescriptions. You’ll know you have prism if you see a little triangle symbol next to it in the prescription paper, like this: ∆. A prism is usually prescribed in lenses to help you bring your eyes’ glaze together.

Some people’s eyes have a tendency to try and pull apart the glaze between two eyes. These are caused by muscle imbalances or fixation disparities. Prism can help ease the symptoms of these imbalances by making the brain think the eyes are working together without pull the muscles too hard.

Progressive Lenses

Progressive lenses allow the wearer to see multiple focal corrections all in the same lens (the top provides distance correction, intermediate in the middle, and reading correction on bottom). The wearer still needs to move its eye to use the various parts of the lens.  Progressive lenses let you wear one pair of glasses seeing both near and far, instead of two pairs!

Pupillary Distance

Pupillary distance is the distance between your pupils. This super important measurement helps make sure that your prescription is placed at the right location in your lenses, so you see through the best spot on the lens.

In some states, the pupillary distance or PD isn’t considered part of your prescription. If you don’t have one on your prescription don’t worry, we can help you! Come into one of our locations to get your PD measurement.

Quizzing Glass

The quizzing glass was popular with both men and women from the eighteenth century onward. Quizzing glass lenses are monocular and can be round, oval, or oblong. The rims are often faceted, or pinchbeck, or mounted with diamonds, turquoise, or imitation stones, and they were typically hung from a chain worn around the neck. Not to be confused with a monocle, quizzing glass was meant to be held by a handle and not held by the eye socket.


Readers (or reading glasses) are glasses that make it easier to read (or do anything really that would require seeing something close up). They can be purchased in various preset magnification strengths, which users choose themselves to match their needs. Off the shelf products are great when the need is in a pinch but it’s important to remember that readers should be customized specifically to the wearer and they may not be the right strength in both eyes, which all off the shelf reader have.


Scientifically speaking, refraction is the ability of the eye bending light so that an image can be formed at the retina. Not surprisingly, most images formed without eyeglasses are blurry.  So refraction in the eye care industry usually means the process of determining your refractive error or in other words, or finding your glasses prescription.


The retina is a layer at the back of the eyeball containing cells that are sensitive to light. These cells trigger nerve impulses that pass through the optic nerve to the brain, forming a visual image.

Segment Height

Segment Height, also known as seg height and SH, is the vertical measurement, in millimeters, from the bottom of the lens in your frames to the center of the pupil, in some case, to the bottom edge of the pipul. Essentially, it is a measurement that ensures that your progressive or bifocal lens is properly placed in the frame.

Single Vision Lenses

Single vision lenses correct for one (single), the distant vision.  Readers can be considered as single vision lenses.  But that is usually referred to as corrective lenses for distance.

Snellen Eye Chart

Snellen eye chart consists of numerous letters of a certain specific size, arranged in rows.  Each row of letters is labeled to read 2020, 20/25, etc. Snellen eye chart is used frequently in an eye test, to quantify how many details one may read at 20 feet distance.  If you can read the 20/20 line, that means you can read it standing at 20 feet away.  The smaller lines you can read, the better is your vision.  It was invented in 1862 by a professor of ophthalmology in the Netherlands named Dr. Herman Snellen.


This number, which will appear on your prescription, specifies how strong your lens needs to be.


Also commonly known as the arm of a glasses frame, it is the part of your glasses that runs alongside your head and rests on the ear.  It holds the frame in place.


Titanium is a silver-gray metal that is lightweight, durable, strong, and corrosion-resistant. But don’t worry, just because it’s a gray metal doesn’t mean it only comes in gray. Titanium eyewear can be produced in a variety of colors for a clean, modern look with a hint of color. Bonus: it’s hypoallergenic!

Tortoise Shell

Tortoiseshell frames mimic the real turtle shells and have a speckled look. The distinctive pattern has mottled yellow, honey, and brown shell spots. While early tortoiseshell glasses were made from actual tortoiseshell, but no longer so.  Please note that NO turtles were harmed in the making of ANY of our tortoiseshell frames in recent days!


Ultraviolet light is an electromagnetic radiation with a wavelength range between visible light and X-rays. The most common source of UV light is the sun. We all know how UV light can damage the skin, but did you know that it can also harm your eyes? Extended exposure to the sun’s UV rays (without proper eyewear) has been linked to eye damage, including cataracts, macular degeneration, and other eye diseases.

Visual Acuity

Visual acuity is another way of describing how well you see. Think of it as a grade scale. 20/20 vision is considered “Perfect” vision. What is means is that you can see a certain row of letters in a standard eye chart at 20 feet.  If you have better than 20/20 vision, (for example, 20/15), it means that you can see at 20 feet what normal people would be able to see at 15 feet.

Visual Field

Think of your visual field as your field of vision. It is the area of the retina that you are able to see with when your eyes are in one fixated on one position.


What you’re going to say when you see the clarity provided by our glasses.


Your first reaction after seeing yourself with our glasses on.