In accommodation, the ciliary body compresses the lens to make it thicker for viewing distant objects and stretches it for seeing close up. Because the eye must constantly change as we focus on different objects, it is impossible to have a clear image of a close and distant object at the same time.
Maintaining Visual Health
Seeing is very much like the telephone system. Vision results from a complicated network of messages that are "communicated" from the eye to the brain. As with the phone system, there are many things that can cause an interruption in eye-to-brain service. Breakdowns in the visual system can be dealt with in different ways—from prescribing medications to dispensing eyeglasses to doing laser surgery.
The key to maintaining a good visual system is early intervention. If you have any of the signs and symptoms listed below, contact your ophthalmologist at once;
- Blurry vision uncorrectable by lenses
- Double vision
- Dimming of vision that comes and goes or sudden loss of vision
- Red eye
- Eye pain
- Loss of side vision
- Halos (colored rays or circles around lights)
- Crossed, turned, or wandering eye
- Twitching or shaking eye
- Flashes or streaks of light
- New floaters (spots, strings, or shadows)
- Discharge, crusting, or excessive tearing of the eye
- Swelling of any part of the eye
- Bulging of one or both eyes
- Difference in size of the eyes
- Drooping eyelids
- Constant squinting
- Sensitivity to light
Even if you do not have any symptoms of eye problems, the best way to maintain your vision is to have early detection and treatment of eye problems. The best way to do this is to have regular examinations by a qualified optometrist or ophthalmologist. Since your age and medical history are the determining factors in the frequency of these exams, the American Academy of Ophthalmology recommends the following guidelines:
- at or before the age of four for children
- every three to five years if you are age thirty-nine or over
- every one to two years if you are age fifty or over, if a family member has glaucoma or other inherited disease, or if you have had a serious eye injury in the past
Even if you have perfect sight, maintaining your vision is as important as any other aspect of your health. Unfortunately our homes, workplaces, and recreational activities are full of hazards that threaten our good sight. Being aware of these hazards is the first step to preventing serious injury or blindness.
The old expression "eyes glued to the tube," which refers to people's love affair with TV, has been replaced with the more recent phenomenon of ''surfing the Net." Everyone, both children and adults, is becoming more computer-oriented and fascinated with the unlimited information and ideas that can be explored on the Internet World Wide Web (www). Our eyes now are glued to a video display terminal (VDT) for our work and schooling, at home to pay bills or find a recipe, and during our recreate on time as we correspond through E-mail or play chess with an opponent from across the world. Even some of the resources for information listed in the appendices of this book are available on the World Wide Web.
When we first began using VDTs there was some concern that they might emit radiation that could cause serious vision impairment. Further study has shown that this is not true. But, prolonged viewing of VDTs can cause serious eye strain, so here are a few reminders for comfortable computer use:
- Place the top of the screen at eye level or slightly below.
- Reduce glare on the screen by lowering the light or using filters.
- Maximize the image resolution by keeping the screen dust free and adjusting the sharpness of the focus.
- Take frequent breaks to rest your eyes and stretch your back, neck, and arms.
