Kid-Focals

By Danielle Crull, ABOM

"Bifocals are for old people." That's what I hear people say and I'm inclined to agree. The reasons that older people wear bifocals are completely different from the reasons why kids wear them. Because of that, we should call children's bifocals something different, perhaps "kid-focals."

As an optician, you are likely to fit 100 pairs of bifocals for each pair of kid-focals. Both types of bifocals may have two separate areas of focus in one lens, but that is where the similarity between them ends: The areas of focus are in different places, the reason they are prescribed is different, even the perceived benefit the patient has while wearing them is different.

BIG PEOPLE

Most adults 40 years and older develop presbyopia. Presbyopia is the inability of the eye to focus closely and is a natural part of growing older. When the eye focuses on close objects, the lens bulges, creating plus power and accommodation within the eye. When a person ages, the crystalline lens loses its elasticity. The surrounding ciliary muscles that contract to bulge the lens also weaken. Eventually, the eye loses its ability to focus and see up close. This results in blurry vision or, as many people complain, arms that are too short. That loss of plus power is then made up in the prescription by the add power of a bifocal.

LITTLE PEOPLE

On the other hand, children haven't lost the ability to accommodate close up. Their lenses are very pliable, and the cili-ary muscles very capable of contracting, so the problems they have are quite different than adults. Most young children who are prescribed bifocals have alignment problems that result from lack of control over the muscles of the eye, not from the inability to accommodate.

While doctors may prescribe bifocals in a young one (6 and under) for a number of reasons, most often it is because of accommodative esotropia. In the normal course of events, the doctor prescribes plus (+) power for the distance and then allows the child's own ability to accommodate to take care of focusing for near.

What happens is that while some children are accommodating, they subsequently lose the ability to keep their eyes straight. The result is esotropia (turning in) at near.

When this happens, the doctor may prescribe a bifocal to do the close focusing for them so they do not lose the ability to hold proper alignment with their eyes in the effort of focusing for near.

Typically the child will present with a hyperopic Rx and then return a few months later with an Rx for bifocals. Properly developing eyes are crucial for normal visual development. Most children are not prescribed bifocals to give them vision, but to keep their eyes developing properly and working together. When a child develops esotropia, this prevents the brain from seeing well out of the turning eye or eyes and can lead to amblyopia or even prevent the child from developing binocular vision.

I can't stress enough how important it is to be aware of the difference in perception between a presbyopic grown-up and an esotropic child. When an adult puts on his or her bifocals for the first time, the vision becomes immediately clear because the bifocals are doing the accommodation that adult is no longer able to do. So Grandpa says, "Wow!

I can see like I used to!" The visual benefit makes training a grown-up to use bifocals straightforward.

On the other hand, when a young child puts on his or her bifocals for the first time, the vision is not necessarily any clearer than it was before because the child still has this marvelous ability to accommodate in the short term. Essentially, the child doesn't see any differently right away. It is only over time that the bifocals do their job because they are necessary to keep the eyes aligned and to develop normal binocular vision. In other words, there is no "Wow!" moment with an esotro-pic child, and the pediatric optician should know well enough not to expect one.

Furthermore, as an optician, we need to be aware that it is completely possible for a child not to use the bifocal at all because they think they can see perfectly well without it. When we fit one of these little ones, we need to make sure the bifocal is impossible to miss and that they have access to the full power of the bifocal that is needed to help with alignment. If we fail to do this, the child will go back to the doctor not only using their bifocals incorrectly, but also with delayed visual development.

BUILDING BLOCKS

Because it is necessary to fit these little ones with the full bifocal add, it is generally counterproductive to fit with a progressive type lens. Progressives can be used well in older children, but when you are fitting a little one (under 8 years old), he or she needs that full add power all the time. Remember, the bifocal is strictly for alignment and not vision, so if you fit one of these kids with a progressive type lens, there still may be some misalignment if the eyes don't go all the way down to the bottom of the channel. Having said that, I have found that after kids have learned to use their kid-focals well, they can transition into a progressive lens quite easily when they are older.

Ruling out progressive lenses leaves us with three basic types of bifocals. They are the flat-top or straight-top segs, round segs and blended segs. Of course, when fitting children, it is recommended to use either polycarbonate or Trivex material for impact-resistance. The flat tops and straight tops come in either 28 mm or 35 mm, and the round segs come traditionally as a 22 mm or 24 mm. However, you can have a digital round seg customized to any specific diameter. I often choose 30 mm because that provides a very generous near-vision area, but this can be modified depending on the size of the frame.

Furthermore, the optician can choose to have the round seg line blended so the bifocal becomes invisible to those looking at the child. There will be about 1 to 2 mm blurred area on the lens where the line would have been. Unfortunately, this blurred area is noticeable to the child when looking through the glasses, so generally I begin using these on kids after they have already learned to use a lined bifocal well. Believe it or not, small children do not necessarily understand that there is a clear area below this blurry part, so there is a chance the child will perpetually look over it and never even use the bifocal.

RIDDLES

Before we take any measurements, the first thing we need to understand is how to interpret the doctor's prescription for bifocal placement. It is standard practice to fit a child's lined bifocal to bisect the pupil when you are looking at the child at his or her eye level. This should be done unless otherwise noted. On the other hand, the doctor may make a note to place the bifocal "just below visual axis." In this case, the doctor would be recommending the line location be at the bottom edge of the pupil. Furthermore, the doctor may note, especially in older children, "at lim-bus" which means at the lower lid margin.

TEETER-TOTTERS

Now that we know where the bifocal goes, how do we get a measurement on a moving target? Short of using a military laser targeting system, the best thing to do when measuring a seg height is to get right down to their eye level. I generally get down on the floor and begin playing with them. I find an activity that they can stand at, and I can kneel, such as playing "High-Five!"

Then I adjust my own height so I am exactly at their eye level, without drawing any attention to what I'm doing, just playing.

Next thing is to put the glasses on the child and do any necessary adjustments that may affect the bifocal height. Once the glasses are positioned well, I can either break out the ruler and measure from the bottom of the frame to the pupils, or draw marking lines on the demo lenses. If the child is pretty cooperative, I just have him look at me and measure like you would for an adult, except, of course, the bifocal position is higher (and the obvious fact that you're on your knees).

If I know the child is not going to want me to put a ruler in front of his face or will likely be unwilling to hold still long enough, then I do things in stages by making a series of marks right on the demo lenses. First, as I'm playing, I eye out where the bifocal should be when he is looking directly at me. Sometimes you need to hold a toy, a shaker or whatever may get the child's interest. Then I take the frames off the little one and make a series of marks on the lens about 2 to 3 mm apart horizontally in the area where I thought the bifocal was going to sit. It can be helpful to make these marks in different colors so that you can get the measurement quickly without having to count from the top or the bottom. It's much faster to look and know that it is the green line that bisects the pupil.

Back to the child, put the glasses back on and play with him again. This time note which line is in the correct position, and that then becomes the "official" bifocal height. These same methods can be used while a parent is holding the child. Sometimes you have a little one that is too shy to just play with you, so you can simply have a parent hold him while standing. Then you can find an eye level position that way and proceed with measuring as mentioned above.

VIEW-MASTER

Measuring a near PD for the bifocal can be a bit tricky. The first thing to be aware of is that a child's comfortable near distance is much closer than an adult, mostly because his arms are way shorter. I use a PD ruler with windows for the child to look through. Again finding your eye level with the child, ask the child to touch your nose. If the child can do that, then you have him at the proper distance for measuring the near PD. If the child is too shy to do that, then just bend your arm, which is holding the ruler so that you are approximately where you think his arm reaches. Staying at eye level within the child's arm distance, hold the PD ruler on the child's nose and cover one eye-window with your thumb.

Next, you will need the child's focus on something between the two of you, so have him look at your nose or a toy. Look for the center of his pupil and match it up to the vertical measurements in the ruler window. Repeat the process by covering the other eye window with your other thumb and measuring. This will give you their monocular near PD. Sometimes I ask the kids to watch my nose and make sure it doesn't move or change colors. The funnier and more engaging you are, the more charmed the kids will be into playing your little game.

TRAINING WHEELS

Once your little patient's kid-focals are ready, you're going to need to help him along a little bit. With adults, you hand over the reading card, and they look down and see that they can read. On the other hand, most of your little ones don't even know how to read yet. In addition, an optician always needs to keep in mind the child thinks he can already see up close just fine without the kid-focals so he is not going to have any incentive to be looking through it like an adult would.

This is why positioning is so important. When the bifocal is high, they only need to look down, and they are right in it. Some kids are great and just take to it right away... actually they put adults to shame because they never whine or complain about it. You will, however, have some children that just don't quite get it right away and resist using it completely. In fact, not using the bifocal has strange telltale signs for which you should be on the lookout. The child will lower his chin to his chest just to look over the bifocal to look at an object in his hand, or hold her head up high and look under her glasses. These are the ones that really need special attention.

So what do you do if you have a little one that resists? First and foremost, make sure the frame is adjusted well. If the child likes to look under them, then get rid of the space below by getting the frame as close to the face as you can, maybe even by adding some pantoscopic tilt.

When everything is in proper position, then we just need to show them how cool everything looks with the bifocal. It won't be clearer, but it will be larger, and in time the child will grow to like the larger image size. We need to engage the child by putting something interesting in her line of vision when she looks through the bifocal. We have been doing this for years with books and gadgets.

Recently, I gathered up all these experiences with children and developed a book specifically aimed at teaching young ones how to use their bifocals. Banana Bobby Gets Bifocals is a great and fun tool that uses hidden images to show kids how to use their kid-focals. In the back of the book are blue stickers that go right over the bifocals in the child's glasses. These blue stickers allow the child to find the hundreds of images in the book that are only visible when the child looks through a blue filter. Showing the parents what good bifocal usage looks like goes a long way toward ensuring proper bifocal use. Plus the best perk is that it's fun. You can not overestimate the value of fun when working with children. You will always get the best cooperation when the child is having fun.

The final test to see if the child is choosing to use his bifocals would be to hold something well above his head but still close. If the child has decided this vision in his or her bifocal is good, he will go to the trouble of lifting his head up high, even to an uncomfortable position to keep looking through the bifocal. Mission accomplished.

READING THE INSTRUCTIONS

I cannot overemphasize how important it is to communicate information not only to the child, but also to the parents. The parents will be there when you are not. It is crucial that they understand how to identify a problem as soon as it occurs. I have the parents watch and explain to them what I'm looking for as I am training the child. I show them the "above-the-head" test, and I recommend that they check their child periodically to make sure they still prefer their kid-focals. If glasses fall out of adjustment, this can make using the bifocal too much of a burden, and the child will fall into bad habits. Bad habits can be quite challenging to break, that's why it's best to avoid them in the first place. I always encourage parents to come in frequently for eyeglass tune-ups.

When fitting any young child with glasses, especially with bifocals, it is a team effort. The doctor, the optician, the parent and the child need to work together to help these little ones along. If a young one fails to use his or her lenses properly, it could lead to amblyopia, poor visual development or even surgery. With a little patience and creative measuring techniques, fitting kid-focals can become child's play.