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How do they affect vision? By Dorothy H. Stiefel Visible light is simply the red through violet spectrum - the color wheel. They are the colors you see in a rainbow. This spectrum contains a small part of the total range of electromagnetic radiation. Just below the red are longer, invisible rays, which operate on a slower wavelength frequency and are called infrared rays. Just above the violet range, also invisible, are shorter rays which transmit their radiation faster and much more intensely. They are called ultraviolet radiation. The invisible ultraviolet is the most dangerous component of the light spectrum to our eyes. The retina is 800 times more susceptible to damage from the ultraviolet or UV end of the spectrum than from infrared radiation. UV radiation is that which causes sunburn. Intense amounts cause corneal burn. For this reason I will focus on the effects of UV radiation. UV that which causes sunburn, Whenever you see the letters nm after a number designating the intensity of ultraviolet (UV) or infrared (IR) you will recognize it as the abbreviation for manometers, a unit of wavelength measurement. Ultraviolet nm densities, which run from 286 to 400 nm, and are defined as UVC, UVB and UVA categories. The UVC is actually below the 286nm wavelength as it consists of that light which is filtered by the ozone layer of the atmosphere. It is also why scientists are so concerned about the manmade products, which continually threaten this natural "filtering" layer. UVB measures from 286 to 320 nm. This is the area we know the most about: Sunburn, UVA, between 320 and 400 nm is the low-dose exposure, which we are not aware of. It is more harmful than once thought and is now recognized as that exposure experienced over a long length of time. It stands to reason why the rays in this group would be more harmful. If you feel the heat from sunburn, as in UVB, you have sense enough (but sometimes not) to get out of the sun. But if you never actually feel discomfort you are more likely to continue to be exposed to harmful radiation.
The normal eye has defense mechanisms to withstand harmful effects of most of the sun's rays. The pupil will contract sharply when exposed to intense light. Squinting is a defense reflex, and when the eye waters it is in effect "perspiring" so as to cool it off. Even plain glass will act as a buffer against burning from the sun. Have you ever noticed when riding in a car all day with parts of your body exposed for long periods of time to the heat of the sun that you do not suffer from sunburn? If you were not protected by windshields and windows you would probably sustain a bad burn. For the same reason, persons who wear regular glasses are protected to some degree. Additionally, parts of the eye serve as "backup" filters. The cornea absorbs UV radiation below 400nm. It transmits energy above 400nm therefore protecting the retina by absorbing what the cornea has not been able to absorb. As the eye ages the damage to the natural filter to the crystalline lens increases. The situation may also generate more pigments (called chromophores or color-seeking and absorbing particles.) The core of the lens becomes progressively yellow with the sun’s exposure; in turn becomes an intraocular UV filter, protecting the sensitive vitreous and retina from excessive light! In the end, this continued yellowing of the crystalline lens may lead to cataract development. These are known as the "sunshine cataracts" and account for some 10 percent of the approximate 450,000 cataract operations performed annually. There are indications that early cataract formation is found in higher altitudes and areas closest to the equator. In Texas, because of its geographic location and reputation for wind and dust, people may be more comfortable wearing glasses with a light tint to them. Most exposure to these wavelengths is not harmful to the eye except at high levels of exposure. In this case snow blindness would present a major problem. As the eye ages the damage to the natural filter of the crystalline lens increases. The situation may also generate more pigments (called chromophores or color-seeking and absorbing particles). The core of the lens becomes progressively yellow with the sun's exposure; in turn it becomes an intraocular UV filter, protecting the sensitive vitreous and retina from excessive light! In the end, this continued yellowing of the crystalline lens may lead to cataract development. These are known as the "sunshine cataracts" and account for some 10 pct. of the approximate 450,000 cataract operations performed annually. There are indications that early cataract formation is found in higher altitudes and areas closest to the equator. In Texas, because of its geographic location and reputation for wind and dust, people may be more comfortable wearing glasses with a light tint to them. RP and Glare For some time now ophthalmologists have been recommending persons with RP to protect their eyes from glare and intense UV rays. One of the most common complaints the TARP human services office receives is trouble with glare. People want to know why they experience so much glare and the safest, most comfortable, and certainly most economical way to shield their eyes. Individuals who have had cataract surgery are known as "aphakic" patients. (Aphakia Absence of the lens of the eye.) When their lenses are removed they no longer possess the natural protection they had been experiencing by the crystalline lens. Cataract glasses, which contain a bubble shape, tend to absorb more light, which would naturally cause more glare in many cases. The individual wearing such glasses will need more protection as opposed to those who have not had cataract surgery. After Cataract Surgery Available alternatives offered after cataract surgery do not adequately filter UV light: Intraocular lens implant - made of material, which absorbs below 320nm and allows greater UV exposure to the retina. It also allows a higher retinal temperature increase than the natural crystalline lens would allow. Eyes will be more apt to water or burn from the lack of proper filtering. Contact Lenses - Soft contact lenses can only filter out UV radiation to approximately 300nm. Hard contact lenses filter out radiation below 320nm. Neither kind replaces any of the necessary protection offered by the natural lens. Eyeglasses do not replace the natural filter but do contain material, which absorbs UV radiation; some are better than others. Standard optical plastic absorbs to approximately 320nm. Photochromic lenses contain chemical properties which have the ability to decrease significantly the amount of UV transmission therefore do a better filtering job than some other types of lenses. While ordinary sunshades cut out a small amount of UV properties, persons with RP who have had cataract surgery usually experience more sensitivity to sunlight and glare. Environment is an important factor. Individuals living in the South and Southwest will experience glare more intensely in the summer than those living in the North. Persons living in the North will experience snow glare. Whatever the conditions, if glare is bothering you to the extent that you are squinting continuously and if your eyes feel as though they are sunburned or watering excessively, you probably need better sunshield protection. Several companies make lenses which cut out much of the UV content carried by direct sunlight. A few are listed below. Be sure to check with your ophthalmologist or optometrist before making a decision to buy any special sunshields. NoIR sunglasses, available in "wraparound" styles absorb UV between 200 and 400nm's and near infrared rays of 800-1500, offer a variety of features. The amber lenses are coated with scratch-resistant material for protection and more durability. Fashion gold wire frames are now available along with a custom-fitting service to provide NoIR lenses for the frames of your choice. Children's small sizes are also available. Spectra-Shield lenses are glass lenses treated with a special coating to block harmful rays. The lenses need to be recoated periodically. Ordinary glasses can also be coated with the Spectra-Shield coating which reflects all UV and IR radiation while permitting 80 percent transmission of visible light. Polarized lenses (Polaroid) are designed to eliminate glare at a certain angle but they do not eliminate glare at a certain angle but they do not eliminate the total spectrum of UV transmission. The ambermatic lens is a photochromic type of lens which transmits an approximate low 11 percent of near UV radiation. Other photochromic lenses are Photogray Extra and CPF 550 lenses manufactured by Corning Glass Works. CPF 550 lenses are available only by prescription, and caution is recommended when driving as some color distortion may be experienced. It is also recommended that these lenses be worn on a trial basis first. An alarming number of sunglasses purchased from nonprescription non-professional vendors may actually transmit a higher amount of UV than if no sunglasses were worn at all. It is essential, therefore, to ask for radiation transmission information from manufacturers when determining the UV filtering capabilities of eyeglasses. Beware of general statements such as "eliminates harmful rays." Ask for SPECIFICS. It is obvious that since all of the alternatives presented after cataract removal do not effectively block harmful UV radiation, special attention must be placed on the best substitute for replacing the natural crystalline lens. Some medications create a photosensitizing of the eye (increasing the sensitivity of your vision to the environment). If you are on medication and experiencing such sensitivity with your vision consult your doctor or ophthalmologist, especially if you are on long-term long-term medications. Some highly exposed environmental conditions to UV radiation are: farming, truck drivers, lifeguards, nurses working with Bilirubin lights in nurseries, construction workers telephone linesmen, welders, and glass blowers. IMPORTANT NOTE: Ordinary dark tinted lenses can deceive the eye in regard to protection. The darker the tint the more dilated the pupil behind it, thus allowing more UV Light than if a person wore no lenses at all. This was a phenomenon I experienced while gardening. One day I removed my sunglasses to view a small detail more clearly, and since the sunlight was behind me and not causing glare I did not think to put them back on. I worked in the garden for an hour, got up to walk across the yard and realized that I was not bothered by glare! It was only upon entering the house that I realized the lack of glare was attributed to my pupils having become very, very small because it took an unusually long time for my eyes to accommodate to the dimmer light of indoors. When I mentioned this phenomenon to the optometrist who helped me with some of the material for this article I really thought I had stumbled upon "The Great Discovery," when all that I had become excited about was the rediscovery of why pupils open and shut! I have diligently protected my eyes for a long time from the physical and psychological onslaught of "suddenness" - sudden darkness, sudden sunlight, flashes of brightness, painful sensitivity to reflections, etc. It is an effective measure of control I have over a very unstable kind of sight. The eye is truly a remarkable organ and having researched this subject has helped me understand that much more about how eyes function and how tough and resilient they really are. - From the 1982 "RP Messenger" Archives Selected Reading and References:
Depression is a many-layered happening. It can hit you squarely and knock you senseless emotionally, or it can subtly take hold and drain your strength - even threaten your identity. Individuals who have had Retinitis Pigmentosa for some time will have become experts in experiencing fear, anxiety, frustration, emotional pain and trauma. I remember having had a session with a therapist who stated: "The blessing of RP is that the vision loss doesn’t occur all at once; the curse of RP is that it doesn’t occur all at once." It is not difficult to understand how depression can strike a person with RP so easily. By the very nature of RP, the threat of unpredictability is compounded by stress and anxiety. One woman recalled that when she felt the "blues" coming on, she’d go to town and buy something nice for herself. Another person said she’d go out and take a brisk walk around the block. And then there was the young woman who took refuge in a luxurious tub of fragrant bath oil whenever she felt "down." Whatever works the best for you, is obviously the best course of action. The important thing to remember is to be alert, recognize the signs, and do something about it. If the "blues" seem to take over your senses, seek professional help!
Do you have trouble looking at photos? Do you turn them every which-way and still remain unsure of what you are looking at? I can remember getting so frustrated and embarrassed when family pictures were passed to me to look at. I'd turn them every angle possible, first quickly, then slowly to try to find a focal point of the snapshot. I knew only too well that if I didn't find quickly what I should be oohing and ahhing about I could expect: "You've got it upside down, Mom." The real crux is having it right-side up and still not seeing anything but a splash of color. Do you spot a familiar building from the distance and when you get up close to it fail to locate the shop you need to enter? Viewing the store from the street before entering the parking lot of the shopping center was easy, but unless I kept my eyes focused on my target, I'd lose my bearings when getting out of the car, supposedly in front of the entrance. I remember feeling like a tourist on my own in a strange city. Well, folks, if what I've described rings an all too-familiar bell, relax, a simple explanation is forthcoming. What is seen at the very small end of a tunnel is too small of a piece of the whole when seen up close but it can be viewed in whole by the arced curve that distance affords all of us who have only a small tunnel of central vision remaining. This has been my situation for quite some time now, and a problem which affects many others. The remedy? When looking at photos I hold them at arm's length. Sometimes, at first, I'll try examining a photo at reading distance. if I draw a blank at what I'm supposed to be seeing I'll close my eyes briefly before holding picture away from me. Then, fixing my eyes on a focal point, I'll bring the photo back to the original reading distance. Behold! The picture will come alive with form and meaning. As for locating that one store in a shopping center I have discovered that as a passenger in a car I must orient myself to landmarks around me again. Needless to say, orientation skills are a necessity when trying to learn your way around a new place you plan to stay in for awhile. More important is to become aware "in transit" before getting into a new area. I think of this type of skill for those of us with tunnel vision as developing a built-in zoom lens camera and following through until reaching a destination. It is so easy to become visually lazy, but remember, there's an "up" side to tunnel vision. You're less likely to be distracted while concentrating, and you can develop your "target" vision into a sharp eagle's eye for bowling, archery, and a wide range of other pinpoint mastery skills.
Ó By Dorothy H. Stiefel "FIRE"! It won’t happen to me, you say. "I have a smoke detector and it’s never gone off," you brag. Well … let’s take a hard look at the entire scenario. How many of you have had the fire marshal speak to you about fire safety and protection? And how long ago? How many of you have actually mapped a way out of your house quickly and safely in case of fire that has already started to spread? The choking smoke of a house fire kills hundreds of people each year. Three of the major causes of fires in the home are cooking, heating equipment, and careless smoking. If you do not instantly know by heart and sense of touch how to evacuate an escape route quickly, this is an article to pay attention to. A smoke detector will help to save your life, but which one is the best one to choose? Do you feel that you have to pay a fortune for the "top of the line" warning system? Well … you might if you fall victim to scare tactics that may involve a free dinner, some free "helpful" gadgets (such as a baseball … all to hear an emotionally charged speaker and then view an awesome video depicting the horror of what a fire can do. There’s a better way! An investigation revealed that in many cases, the fire marshal would come to your house if you live alone and/or have a disability. (Check your own area for more information on this. He can tell you what kind and how many detectors are advisable for your home. He will also let you know what your best escape route, give or take some modifications that have to be made to effectively work in a real-life situation. Escape Plans Every member in the household should know at least two exits from each room. Make sure doors and windows needed for exit are easy to open. If the exit involves an upper story window, make sure there is a safe way to reach the ground. If your smoke detector is more than 10 years old, you should discard it because the mechanism inside wears out. First Alert Systems are popular, and others which use a combination of ionization and photoelectric systems are available at an affordable price. Be sure you can hear your detectors’ alarms. Special smoke detectors that flash a light in addition to sounding an audible alarm are available for residents who are hearing impaired. TIPS
Making The Most of Your Environment
When you dine out, choose a seating arrangement in corners where noise is reflected. Select seating where lighting is over your table. (If you find a favorite restaurant location, ask the manager to reserve the table for you if possible.) Get in a habit of counting the number of steps or stairs you frequent. Soon you will have memorized them and you won’t have to spend so much time "checking out" your environment. Storing your "Stuff." If you have household items or personal things you want to keep but don’t have a "home for them, keep a shoebox as a catchall for your "stuff." Keep it in a handy place and don’t change the location! Always be conscious of creating good contrast so you can spot items in your home. For instance, I would place a black stapler on white paper on a dark wood table. Odds & Ends All excerpts are by Dorothy Stiefel unless stated otherwise. Did you know that cataracts are recognized as a component or complication of all genetic types of Retinitis Pigmentosa and Usher syndrome of either type? (that with proverbal deafness or that with post-verbal hearing impairment.)
One of the most exciting advantages of my volunteer work is meeting so many interesting people. Whether it be through the RP Hotline, a friendly local chat, or an out-of-town visit, I am continually reminded how rewarding it all is. During my travels and many conversations with individuals with RP, I have gathered commonly used expressions and some unusual situational experiences. The following are the "The Most":
"Have you ever watched the body language of people "who just don't want to hear it?" Yawning is 10 on the scale. Rubbing the eyes make for a good 8. I'll give turning the pages of a magazine a testy 5!
Clutter syndrome! A plan of action!
SAFETY AND SELF DEFENSE Do you feel safe when you are "out and about"? Do you do a lot of walking or traveling on your own? If the answer is "YES", you may want to take a good look at personal self-defense strategies. We are constantly bombarded and surrounded by all kinds of violence and sadly it is not going away! Our streets, our schools, the workplace, and yes, even our "Home Sweet Home" is not exempt from random or personal attack. Are people with disabilities more at risk? I don’t think so. The mugger or rapist is no respecter of race, age, sex or disability. We may feel that we are more vulnerable but we are certainly not singled out. So, what methods of self-defense can be employed to minimize the risk of being a target for assault or purse snatching? Supposing that you have never taken a self-defense course, let’s review some basic areas. Awareness of the immediate environment at all times is a priority. Be on guard and prepared to protect yourself or a loved one. As you go about your day-to-day business we must be aware of the people around us as well as the people with whom we come in contact. We must teach our children the rules of safe behavior as if they are the "ABCs" of life. Our streets are already battlefields; hallways and corridors can become prisons that leave no chance for escape from a watching assailant. Actively listen and think about where you are at all times. Being aware of your "space" at any given time as well as keeping defense devices in readiness on your person will give you the precious time you will need to summon for help or to escape from imminent danger. The perpetrator most often will not be a stranger. The 1991 issue of the Journal if Visual Impairment and Blindness" stated that … "women are three times more likely to be raped by an acquaintance than by a stranger …81 percent of those who had been raped knew their attackers and 57 percent were dating them. In the past, it was generally advised that women not resist their attackers. However, results of studies have divulged that "women who resist are more likely to thwart the rape …(and are) not necessarily more severely injured when they resist." Self Defense Strategies Laura Bozeman, mobility instructor for the University of Texas in Austin, and holder of a brown belt in karate, has an explicit message: "don’t be a victim!" It is very important, she remarked, not to be perceived as a victim. Don’t look like a victim. Maintain a confident composure by presenting yourself as a person who is in control. Show that you know where you are going, and that you are prepared to fight back. In the event of an attack, "use techniques that will hurt your aggressor, she advised. "Punch with your fists, scream, kick the groin, and if necessary, use the top of your head to initiate a blow to the attacker’s forehead, just above the eyebrows between the eyes—a very vulnerable area of the face. "If you have the slightest warning, Ms. Bozeman said, and can see fairly well, run in the direction of traffic or people. If you are waling with a rigid cane, you are better off dropping it to free your hands to punch your attacker—and scream as you do so!" I have a larger than golf ball size "marshmallow" tip on my folding cane that I know hurts. If I am carrying it or have while I am sitting in the car, it will serve as a lethal weapon. Self-Defense Rules of Thumb
In addition, there is a body alarm, which was demonstrated to me by my mobility instructor. The PAAL is a personal attack alarm that emits a high-pitched noise unlike any other device. WANT TO HELP? Ask your community college to offer self defense classes. Call your local police department to see if they hold a "Citizen’s Police Academy class. If not, request that they offer a special class for citizens with disabilities. Ask the organization you are affiliated with to hold presentations on self-defense techniques that visually impaired and blind people can learn how to execute. Above all, use common sense. Choose devices that you will be able to operate quickly and effectively, keep them in working order, and never let your guard down. Quick Action For Injuries When I was managing a household of ten, which included our pet Manchester Terrier, I often collided with, tripped over, or bumped into tots, toys, and of course, the Terrier, Princess. I got hurt on a number of these mishaps, but I soon became very innovative about "fixing" my injuries. I often looked like a battered wife, and the many black-and-blue bruises were embarrassing. I used to just run cold water over the hurt area, but it didn’t help very much and I still had to live with the whelp and the blue color. One day I fell and hurt my foot. I couldn’t run cold water over it in the bathtub, because one of the children was playing in it. Frantically, I removed an ice cube tray, loosened some cubes and put them into a plastic bag. Then I placed a tea towel around it. I propped my foot up, and tried to balance the slippery, melting cubes onto the center of my leg where I had sustained a nasty bump. I wasn’t very successful for all the trouble, either. The ice was melting and leaking onto the towel which then began to drip, getting my sock wet. Having now been swept up into a domino effect situation, I realized I had a mess on my hands. This is not a good idea, I thought. I was frustrated because it had taken me over ten minutes to get everything together, and now my big toe was throbbing. The next day the toe had burned blue. One day, some time much later, I hurt myself again! Remembering my previous incident and the frustration, I hobbled to the freezer and yanked a bag of frozen corn out of the freezer, grabbed a towel, and slapped it on my injury, this time, on my kneecap! I may not have solved the problem of sustaining so many bumps and knots, but now I keep a ready supply of frozen corn and peas that will get to the site of the hurt within seconds. No mess, no fuss, no bother, and I don’t get to the whelp stage, either! |
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