2010-04-28-Two Kinds of Light-Friend and Foe
Seminars@Hadley
Two Kinds of Light: Friend and Foe
Presented by
Marshall Flax
Moderated by
Don Golembieski
April 28, 2010
Don Golembieski
Let me welcome today’s presenter, Mr. Marshall Flax, F-L-A-X, who is a certified lower vision therapist and he’s going to be talking to us today on Two Kinds of Light – Friend and Foe. So I’d like to welcome Mr. Flax and I’ll turn the microphone over to him at this point.
Marshall Flax
Good afternoon everybody. This is the first webinar I’ve done, so I’m sure I’ll be used to the format in a few minutes, but it does take me a while to get used to not having a live audience right there where I can hear you breathing. So everybody breathe heavily and maybe it’ll make its way up here to Wisconsin in the U.S. where I am.
Today I’m going to talk to you about light and as a Low Vision Therapist I work with people and I tell them all the time that if you have low vision light can help you and light can hurt you and you have to learn how to manipulate it. So my goal today is to help you understand that light is a tool and that you will have to learn how to work it if you’re going to make it work well for you.
We all know that if there’s too little light, we usually don’t see well – everybody understands that part. But people forget that if there’s too much light or light from the wrong direction, you probably won’t see too well either.
As a Certified Low Vision Therapist, I spend a lot of my time teaching people about how to get the most useful lighting. And today of course I’ll be talking about light and lighting from that perspective of a Low Vision Therapist for people who have impaired vision.
But my suggestions and ideas will be necessarily generic and I hope that you’ll understand that none of what I say can be taken as a specific recommendation for what you should do. Everybody’s situation is unique and I recommend that you consult with your own CLVT or your eye doctor if you have specific questions about how lighting might affect your unique situation or if you have questions about your own personal eye health.
So let’s talk first about indoor lighting. For a person with low vision, we can divide it into two types of indoor lighting – area and task or directed lighting. And task is if you’re my age and you can’t hear that sound very well, that’s T like in Tom, A, S like in Sam and K like in kitten – task lighting. I use that word a lot when I’m talking about this kind of lighting – task or directed lighting.
So let’s say with area lighting, which is pretty much for lighting up an area, its function is to help you locate the walls, the doorframes and the furniture. For a young person without a vision impairment, area lighting is often enough light for reading. In fact, kids seem to be able to read in a room where – to those of us who are older – there’s simply not enough light at all.
This is due partly to the changes in the eye associated with normal aging. The older one gets, the more light one needs. Children don’t require as much light to do the same task as a 75-year-old.
Area lighting is usually a ceiling fixture or a table lamp or a floor lamp. The lights will have a shade to diffuse the light evenly over a broad area so that everything is more or less evenly lit. This is great for helping you see the coffee table instead of smacking into it, but usually this light isn’t very useful for reading.
There’s sort of an exception to that, however, so for those of you with low vision or those of you who don’t have low vision, how many times have you tried to get more light on your page or the craft you were trying to do by sliding all the way over to the edge of the couch or sofa and leaning or stretching over to get the book or paper as close to the light as possible?
Well, this works, and we’ll talk about why this works, but it can be very physically tiring and uncomfortable to do this for very long. So that’s where area lighting sort of helps out but it’s not really a practical solution.
Task lighting on the other hand, does a terrible job usually of illuminating the room, but it is the lighting of choice for reading and for other near-vision activities. A task light is usually a floor-standing or desk lamp with an adjustable arm, often gooseneck that has a shield or cone to direct the light at the visual target, a low vision therapist term. If I’m referring to whatever it is the person is looking at, whether it’s a book; whether it’s a crossword; whether it’s stitchery, I may often just refer to it as the visual target.
Now to get this task light to really work for you, you’re going to use the law and by that I mean the laws of physics, specifically you’re going to use the inverse square law. Now I’m not a physicist, but I learned enough about the inverse square law to be able to relay it to you and you’ll know how this works because you’ve used it all your life.
The inverse square law says that if you move a light so that it is twice as far away as it was when you started, you’re going to need to increase the amount of light by four times to get as much light on the object as you had a minute ago before you moved it. So, move it twice as far away, you’re going to need four times as much light. Photographers use this kind of thing all the time and figuring out when they move their lights around how much light they’re going to put on the person they’re taking a portrait of.
But the opposite is also true and it is much more important for people with low vision. If you move a light that’s four feet away and you move it into two feet, common sense would say it’s twice as bright as it was. In reality, it’s four times brighter when you come from four feet to two feet because you’re going to square that number.
Bring it in another foot – from four feet down to one foot away and it’s 16 times brighter than it was at four feet. This is why you slide over to the edge of the couch and hold your book as close to the light as you can if you want to see it better. This is why when you have something that’s hard to see, you move as close to a light as you can if you’re able to see it at all because the closer you are to the light, the brighter it’s going to be.
One of the greatest things about this is it’s free; doesn’t cost you a penny to move close to the light. This is one way to really make light your friend. It’s like a friend who likes to come over and shovel your sidewalk or mow your grass for free.
The other part of task lighting is the shield, or cone or the lamp should be shaped and positioned so that it puts the light on the page and not in your eyes. The area lamps that we talked about have a soft fabric shade or a translucent diffuser so that the light is spread evenly. This is not what you want in a task light. You want the light directed at the target, so a cone or a shield pointing down and protecting your eyes from the direct light that will cause glare, which we’ll also talk about in a little bit.
Finally, another equally important feature to look for in a task light is the flexibility of the arm. I see many lamps on the market that appear to be flexible and adjustable. They will have what looks like a gooseneck, a plastic reticulated coil that seems like it should adjust. Well, when I try to adjust them, I find that they bend only a little bit and often they cannot twist very much; they can barely bend up and down.
Personally I want a task lamp on a long piece of gooseneck with a shield or a cone that can rotate so that I can sit comfortable and bring the light down to where I want it, not the other way around. So if you’re a consumer, think of this; if you’re a practitioner in low vision, think of this. Get comfortable; get how you need to sit for the activity that you’re doing and then find the lamp that will get to where it needs to be while you’re comfortable.
So many times we do it the other way around where we start with the lamp and we end up contorting ourselves in a very uncomfortable way in order to get close enough to make the lamp useful or to get to a place where the lamp’s not shining in our eyes.
Before you buy a lamp you should position it for reading. Try sitting in a chair the way you want to sit and make sure that the lamp will bend and twist in a position that works best for you. I happen to be a very tall person and I have a long torso, so I get up a lot higher in the chair than my wife, for example, who’s much shorter than I am.
If the same lamp doesn’t have enough bend in it, it’s only going to work for one of us at best and probably won’t work for both of us. Remember that the lamp should be below the level of your eyes, the head of the lamp where the light source is.
Older adults got taught, in fact I may be in that category because I think I got taught the reading light was supposed to come over a particular shoulder and I have my patients in low vision who are in their 80s and 90s – they can still remember being taught over their right shoulder or their left shoulder, wherever it was.
But for low vision it’s not over your shoulder. It’s having that lamp out in front of you, below the level of your eyes, about six to eight inches from the page or the visual target. When I demonstrate the four standing gooseneck clamp I use when I do low vision evaluations, people are pretty impressed that I only have a 60-watt household bulb in the lamp.
I do this very intentionally - keep a low wattage bulb in there - because people generally think it’s gotta be a fancy bulb that’s making this work so well. But I want them to see, no, a plain old 60-watt bulb will do a great job for you if you can position the lamp where you want it. It’s not the wattage of the bulb that makes the big difference.
So to make light our good friend and our buddy when we’re doing near-vision activities, remember you want it close to the page or task or visual target; you want it positioned so that it’s out of your eyes and you want it to be adjustable, tiltable so that you direct any glare that’s coming off the surface of what you’re looking at – make that glare bounce away from your eyes so that you can see.
Most of you probably have experience with reading a magazine with shiny paper and how hard that can be with that glare bounding back off the paper. But if you have a lamp that’s adjustable, you should be able to sit comfortably, tip that lamp so the glare spot – it’ll still be there, but it can be off in some remote corner of the page where it won’t be interfering with your ability to read.
Keep in mind that the most important feature is the fixture. I’m sorry. I forgot we’re going to talk about light bulbs. This brings us to what kind of light bulb is our friend and what kind of light bulb is our enemy. But I wanted to go back and remind you that it’s the fixture more than the bulb that’s important.
Everybody can understand that a zillion-watt light bulb in the wrong place is not going to be your friend. So basically, we have four or five choices for indoor directed lighting – incandescent; fluorescent; full-spectrum; halogen and I’ve added LED. They’ve all got their good points and their not-so-good points.
But the one that works best for you will be – can I have a little drum roll out there – the one that works best for you will be the one you like the best. There is no one task light bulb that is good for everyone, or even for most people, at least in my experience.
Also I don’t know of any reliable way to pick your type of light bulb based on your eye disease. I see a lot of advertising that would like us to believe that if you have macular degeneration, then you should use bulb X or if you have glaucoma, bulb Z is the light for you. But I don’t know where their proof is.
Now if you know of research in this area, I’m seriously interested in finding it and I’d appreciate it if you would send a citation or some kind of note to let me know where I should be looking to find this.
Alright, let’s start with LED which is a relatively new product. LED stands for light-emitting diode. It’s a tiny little light, very bright, uses very little energy. It’s relatively new on the market but based on what I’ve found, there are only a limited number of products available and because of that I’m going to skip it.
They’re there but, boy, you just don’t get much selection – that’s the problem. So rather than put a lot of time into something that’s hard to find in what you’re really going to need, we’re going to move on to fluorescent.
Remember, we’re talking about task lighting now, not area lighting. So generally fluorescent is used for area lighting, like a big store or a school or a warehouse. The big advantage is that it doesn’t put out a lot of heat and it uses less energy. The big disadvantage is that it puts out a lot of UV – ultraviolet light – and there is some evidence that excess UV light and blue light may be bad for our eyes.
Now there’s controversy about this and there’s enough controversy and facts that this topic alone would be a good Hadley webinar, but I’m not going to go into it in great depth today. Let’s just say if you’re going to use fluorescent light for reading, you should probably consider wearing glasses with UV filters or blue blockers just to be safe.
So here’s what Dr. Lilas Moke, a low-vision ophthalmologist in the Detroit area, who has also been a Hadley webinar participant, this is what Dr. Moke says in her book on macular degeneration about blue light.
She says, “Can blue light rays cause macular degeneration? Can you reduce your risk by protecting your eyes from blue light? The answer is maybe. Although the laboratory studies on animals seem nearly unanimous, the real-world studies on people have produced conflicting results. Some studies positively link macular degeneration with any kind of light exposure; other studies have found a weak correlation between macular degeneration and blue light exposure; and yet a third group of studies has found no correlation at all between macular degeneration and sunlight.”
So while these results, now that Dr. Moke has stated absolutely that blue light contributes to the development of macular degeneration, she believes it’s certainly possible. With that in mind, I’m going to err on the side of caution and just say since there may be some connection out there, you probably want to protect your eyes the best you can.
The blue light issue is also true for the full spectrum lights or daylight simulating bulbs. There can be a lot of UV and blue light which, as we just learned may be harmful to your eyes. One of the most knowledgeable people in this area of blue light and its possible effects on the eye – and someone with a strong opinion about it, is Dan Roberts of MD Support.
So if you’re really interested in learning more, I’d send you over to Dan’s website which is M like in macular; D like in degeneration, or M like Michael; D like David – that’s easier – MD Support and read what Dan has to say about blue light toxicity.
The next kind of lighting is halogen. Halogen is a really bright white light. It was a real hot item a few years ago before compact fluorescent bulbs because it was bright but it doesn’t take as much energy as an incandescent bulb for the same amount of brightness.
The problem with halogen is they get very hot and there’s a concern for people either burning themselves when they touch the lamp or something coming in contact with the lamp and starting a fire. And for those reasons I generally don’t recommend halogen bulbs.
There were cases with the floor-standing halogen torchiere lamps – that’s a lamp with a sort of a bowl at the top and a halogen lamp and it would shoot a lot of nice light up to the ceiling and it would bounce around and light up a room very well or that corner of the room.
But somebody’s drapes would blow in the wind and suddenly it would land on the lamp and then it would set on fire and burn down the house, so a lot of those lamps have gone out onto the curb now because of that fire risk.