Sunglasses are popular for comfort and fashion, but now there is medical evidence supporting the use of sunglasses to protect the long-term health of the eyes.
More than a dozen studies have shown that spending hours in the sun without proper eye protection can increase the chances of developing age-related eye diseases like cataracts and macular degeneration. Ophthalmologists now recommend wearing UV-absorbent sunglasses and brimmed hats when in the sun long enough to get a suntan or sunburn.
People mistakenly confuse the ability of sunglasses to block UV light with the color and darkness of the lenses. In truth, UV protection comes from a chemical coating applied to the surface of the lens. Shop for sunglasses that absorb 99 or 100% of all ultraviolet (UV) light. Some lens manufacturers' labels say "UV absorption up to 400 nm." This is the same thing as 100% UV absorption.
In addition to UV light, sunlight also has low levels of infrared rays. Infrared wavelengths are invisible and produce heat. The eye seems to tolerate infrared well. Research has not shown a connection between eye disease and infrared light ray exposure.
Polarized lenses cut reflected glare, like sunlight bouncing off water, pavement, or snow. Sunglasses with polarized lenses are popular and useful for fishing, driving, and skiing. Polarization has nothing to do with UV light absorption, but many polarized lenses are now made with a UV-blocking substance.
Wraparound glasses are shaped to keep light from shining around the frames and into the eyes. Studies have shown that enough UV rays enter around ordinary eyeglass frames to reduce the benefits of protective lenses. Large-framed, close-fitting wraparound sunglasses protect the eyes from all angles. Wraparound sunglasses should be considered by commercial fishermen, mountain climbers, skiers, or anyone who spends time at high altitudes or on the water. |
Strabismus refers to misaligned eyes. If the eyes turn inward (crossed), it is called esotropia. If the eyes turn outward (wall-eyed), it is called exotropia. Or, one eye can be higher than the other which is called hypertropia (for the higher eye) or hypotropia (for the lower eye). Strabismus can be subtle or obvious, intermittent (occurring occasionally), or constant. It can affect one eye only or shift between the eyes.
Strabismus usually begins in infancy or childhood. Some toddlers have accommodative esotropia. Their eyes cross because they need glasses for farsightedness. But most cases of strabismus do not have a well-understood cause. It seems to develop because the eye muscles are uncoordinated and do not move the eyes together. Acquired strabismus can occasionally occur because of a problem in the brain, an injury to the eye socket, or thyroid eye disease.
When young children develop strabismus, they typically have mild symptoms. They may hold their heads to one side if they can use their eyes together in that position. Or, they may close or cover one eye when it deviates, especially at first. Adults, on the other hand, have more symptoms when they develop strabismus. They have double vision (see a second image) and may lose depth perception. At all ages, strabismus is disturbing. Studies show school children with significant strabismus have self-image problems.
Amblyopia, or lazy eye, is closely related to strabismus. Children learn to suppress double vision so effectively that the deviating eye gradually loses vision. It may be necessary to patch the good eye and wear glasses before treating the strabismus. Amblyopia does not occur when alternate eyes deviate, and adults do not develop amblyopia.
Strabismus is often treated by surgically adjusting the tension on the eye muscles. The goal of surgery is to get the eyes close enough to perfectly straight that it is hard to see any residual deviation. Surgery usually improves the conditions though the results are rarely perfect. Results are usuallybetter in young children. Surgery can be done with local anesthesia in some adults, but requires general anesthesia in children, usually as an outpatient. Prisms and Botox injections of the eye muscles are alternatives to surgery in some cases. Eye exercises are rarely effective. |
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To see clearly, light rays must be bent or refracted to focus on the retina, the light- sensitive nerve layer that lines the back of the eye. The cornea and lens of the eye work together to bend or refract light rays and bring them together on the retina. If a refractive error is present, the light is not focused directly on the retina, so images appear blurry.
Myopia (nearsightedness)
Distance vision is impaired when the eye is too long in relation to the curvature of the cornea. This causes light to focus before it reaches the retina. Close objects look clear but distant objects appear blurry.
Hyperopia (farsightedness)
Close vision is impaired, with some impairment of distance vision, as well. The eye is too short in relation to the curvature of the cornea. Light rays are not yet in focus when they reach the retina, so images appear blurry.
Astigmatism (the cornea is oval shaped instead of round)
The irregular curvature of the cornea causes light to focus on more than one point on the retina. Uncorrected astigmatism impairs both distance and near vision.
Presbyopia (aging eyes)
When young, the lens of the eye is soft and flexible, allowing people to see objects both close and far away. After the age of 40, the lens of the eye becomes more rigid, making it more difficult for the lens to change its shape, or accommodate, to do close work such as reading. This condition is known as presbyopia and is the reason reading glasses or bifocals are necessary at some point after age forty. |
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The key to avoiding the irritation and infection sometimes associated with contact lens wear is proper cleaning.
There are two main types of lens care systems: heat and chemical disinfection. The appropriate choice depends on the lens type, duration of lens wear and an individual's own biochemistry. Regardless of the type of disinfection system you choose there are a number of common steps that must be followed.
Always wash your hands prior to handling your contact lenses.
Remove one lens and place it in the palm of your hand. Apply a few drops of a contact soap, usually called cleaning solution. Rub the soap onto both sides of the lens surface to help remove deposits, debris, protein build-up, and any bacterial film. Removing surface deposits and other debris not only contributes to improved vision and comfort but also reduces the risk of infection and allergy. Soft extended-wear contacts may be the most likely to develop a protein build-up that can lead to lens-related allergies.
After thoroughly cleaning the lens, rinse it with commercially available sterile saline solution. Homemade saline solutions have been linked to serious eye infections and should never be used.
After cleaning and rinsing, lenses need to be disinfected. You and your ophthalmologist will pick the best system for you, but make sure you understand the instructions and follow them. Heat and chemical disinfection methods each require several hours of disinfection time.
After disinfecting, rinse the lens with sterile saline before putting it in your eye.
Your empty contact lens case should be thoroughly rinsed with warm water and allowed to air dry. All contact lens cases need to be cleaned frequently, including disposable lens cases. |
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