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frame front.

frame front. Another name for this, by the way, is the chassis (pronounced chasee). This is the part of the frame that surrounds the lenses. It consists of the eyewires that hold the lenses and the bridge between the eyewires.



bridge, which is the portion of the frame between the lenses that sits over the nose. As you learned from your reading, bridges come in a variety of widths and shapes because people have many different nose shapes.



temples—the parts of the frame that go on the sides of the head to hold the glasses in place over the ears. Think of the temples as the “arms” that attach to either side of the eyewire. Some frames have removable temple tips that cover the ends of the temples.



nosepads, which are pads that sit on either side of the nose. Often they are made of hard plastic or soft silicone. They’re typically attached to the frames, held in place by the pad arms.



endpieces are the very outer ends of the chassis where you’ll find the hinges that connect the temples to the frame front.


things to consider when you’re helping a person select frames.

things to consider when you’re helping a person select frames. These include your client’s age and lifestyle and the purpose of the glasses. Also, some frame materials are lighter or sturdier than others, and some are easier to adjust or hold their shape better.and allergies.



allergies. People who choose nickel frames because of their low cost or lighter weight may find that this metal irritates their skin. In addition, nickel can react with sweat, turning people’s frames and their skin green where the frame touches the face. In cases like this, you can suggest hypoallergenic metals like stainless steel or titanium. Some plastic frame materials such as Optyl are also hypoallergenic.People can also be allergic to the material used in the nosepads on their frames. In these cases, you’ll want to look for hypoallergenic nosepad materials like titanium or PVC.



zyl. This originally stood for zylonite, but zylonite was banned because it was very flammable. These days, we use the term zyl to refer to plastic frames made from cellulose acetate.Zyl frames have lots of advantages: they come in many colors, they’re easy to adjust, and they tend to be sturdy. However, some patients may be allergic to zyl. As I’ve noted, metal or Optyl is an option for patients who have allergies to zyl. But Optyl isn’t a popular choice these days because it easily loses its adjustment in warm weather.


Metal frames

Metal frames are fairly lightweight, they’re strong, and they’re easy to adjust, but they can get out of shape more easily than zyl frames. Fortunately, it’s simple to bend them back into the right shape. Zyl frames tend to be more stable—but it can be hard to get them back in shape when they do lose their alignment. Zyl can also become brittle with age, lose its color, and break easily. Aluminum or stainless steel frames, on the other hand, can corrode or snap over time.



Titanium is the lightest and strongest of the metal frames, and it’s corrosion-proof. Titanium also tends to be more expensive than other metal frame materials. Lightweight materials like titanium and stainless steel are good choices for heavier prescription lenses, and your clients may find them more comfortable than frames made from other materials.



Polycarbonate, a special type of plastic, is impact-resistant and extremely lightweight. It’s used for prescription lenses as well as safety frames, sports frames, and sunglasses.


The two categories of glasses include:

Ophthalmic frames used for prescription lenses.
Non-ophthalmic frames used for sports, sun protection, or eye protection.


measurements to ensure that a frame will fit just right:

think in threes.” That’s because it takes three measurements to ensure that a frame will fit just right:

The eyesize.
The bridge size.
The temple length.
When you look at a pair of frames, you’ll typically find these three measurements (in millimeters) stamped on the inside of one of the temples.


When you’re measuring frames, you’ll use what?

When you’re measuring frames, you’ll use a pupillary distance (PD) ruler.


how To measure the eyesize of a frame,

To measure the eyesize of a frame, you’ll begin by placing the PD ruler across the center of one of the eyewires horizontally. It’s important to measure the widest part of the frame. If it’s a thick plastic frame, be sure to measure from the center of the width of the eyewires.


Here’s the most important conversion to remember:

Here’s the most important conversion to remember:

1 mm = .039 inches


measuring bridge size.

bridge size. To find this number, measure from the vertical center of the inside of the frame straight across the bridge. (See the picture below.) Sometimes the physical bridge of the frame is high or low, so you won’t necessarily start at the height of the frame bridge itself.


Measuring the temple length

Measuring the temple length is a bit more difficult. First, you’ll measure from the temple end that attaches to the eyewire at the hinge out to where the bend begins. Next, you’ll move the PD ruler, start at the very end of the temple tip, and measure to the spot where you previously determined that the bend began. Adding these two numbers will give you the full temple length as shown below:


the PD measurement.

when you’re ordering glasses measure the distance between the centers of a person’s pupils in millimeters. (See the picture below.) We call this the PD measurement. You’ll use this measurement when you order prescription lenses, so you can ensure that the optical center of the lens is in front of the pupil when the person looks straight ahead while wearing the glasses.


the distance PD

the distance PD—the distance between the pupil centers when the person is looking in the distance.


the near PD,

the near PD, which is the pupil distance when the person is looking close up (while reading, for example).


two pupil distances you’ll need to measure when you’re fitting a person for glasses.

the distance PD and the near PD, The pupil distances are different in these two situations because of the convergence, or the slight moving inward, of the two eyes toward the nose when the person looks closely at something.


There are several ways to find a PD measurement. Here are two common ones:

There are several ways to find a PD measurement. Here are two common ones:

1. With the person facing you, have the person look at your left eye, and place the zero of the PD ruler at the very outer edge of the person’s right iris. Why the iris and not the pupil? It’s pretty easy to see the edge of the iris, so I prefer using this landmark instead of the pupillary light reflex in the center of the pupil. When patients have dark eyes, it can be difficult to see the pupillary reflex.

Then, without moving your hand or the PD ruler, look at the inner iris edge of the person’s left iris, and measure the distance in millimeters.

PD measurement using the iris

The number you come up with should be somewhere between 50 and 70 millimeters. It’s typically about 50 to 60 millimeters in children and about 60 to 70 millimeters in adults. This would be the person’s near PD measurement.

Now—without moving your hand or the PD ruler—ask the person to look at your right eye, and read the new measurement at the inner edge of the person’s left iris. This is the person’s distance PD measurement.

2. The second common method of measuring PD—and I think you will like this!—is to use an automated PD measuring instrument called a pupillometer. Here’s what it looks like:

A pupillometer

When you use this device, the only thing your patient or customer will need to do is look into the handheld instrument as if looking through a pair of binoculars. And all you need to do is slide the markers over the centers of the person’s pupils and read the LED reading off the instrument.


two other categories of PD

binocular and monocular.


binocular PD

binocular PD—that is, the distance between the centers of the pupils.


monocular PD

monocular PD—the distance from the center of one pupil to the center of the nose—can be very important when you need precise measurements for strong prescriptions or progressive lenses. The only way to take an accurate monocular PD is with a pupillometer.


why Getting PD measurements just right is crucial,

Getting PD measurements just right is crucial, especially if a person’s lenses are very thick, there’s a prism in the prescription, or the person’s eyes are not aligned. If the optical centers of lenses aren’t ordered with the person’s correct PD in these cases, the person will have little chance of seeing well.


Accurate PD measurements are also very important when you’re ordering bifocal lenses

Accurate PD measurements are also very important when you’re ordering bifocal lenses.

Bifocals have little segments placed toward the bottom of the lenses. These segments contain the person’s reading prescription. When the person wearing the glasses moves his or her eyes downward to read, the bifocal segments need to be in the correct position (based on the near PD) so the person’s eyes are looking through the bifocal segments.