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Do you play a sport, such as tennis or baseball? Do you like to
do carpentry? Do you use a lawn trimmer? These and many other
daily activities put people at risk for eye injuries. Eye injuries
are common, especially impact injuries; that is, injuries caused
by something striking the eye. These injuries can range from a
mild corneal abrasion to hyphema (bleeding into the anterior chamber
of the eye), retinal detachment, penetration of the eye, or a
ruptured globe (the eye breaking open). Some injuries heal with
no after-effects, but others result in impaired vision or - especially
in the case of ruptured globe - loss of the eye. Yet the great
majority of these injuries are easily preventable.
For more information
on Preventing Eye Injuries, please
contact Paul F. Vinger, M.D., Director,
Vision Performance and Safety Service
at the New England Eye Center and Associate
Clinical Professor of Ophthalmology
at Tufts University School of Medicine,
978-369-1310.
The nature and severity of an impact injury to the eye depends mainly
on the impacting object's mass, speed, hardness, size, and sharpness.
Other factors are the location of the impact and the predisposition
of the individual eye to injury.
Sharp objects commonly cause laceration of lids
and the eye itself, often leaving foreign bodies in the eye. Automobile
mechanics and others whose work involves striking metal have an
especially high incidence of this type of injury, since they are
continually exposed to flying metal fragments and rarely wear eye
protection. Common activities, such as using a lawn trimmer, also
result in sharp objects with sufficient energy to lacerate the eye.
Running into a sharp twig is a frequent cause of eye injuries to
both adults and children.
Another important cause of this type of injury
is eyewear failure, which is almost completely preventable. Since
shattered eyeglass or sunglass lenses may have fragments which are
extremely sharp, the energy required to shatter the lens can be
sufficient to rupture the eye. By wearing the wrong eyeglass or
sunglass lenses, you may put yourself at risk of converting what
would have been a minor injury into a ruptured eye.
Small, high-speed blunt objects often cause perforation
of the eye, with a poor prognosis even with modern surgical techniques.
A major cause of this type of injury is BBs. You should be aware
of how little energy a BB requires to penetrate the eye. BBs have
been known to pass through the eye into the brain, resulting in
death. Do not let children play with BB guns unsupervised.
Larger blunt objects that can still fit inside
the orbital opening (rim of the eye socket) are numerous. Examples
are paintballs, squash balls, golf balls, golf club heads, hockey
sticks, ski poles, polo mallets, extended fingers (for example,
in basketball), wood "kicking back" from a table saw,
and some industrial materials and automobile crash debris. If these
objects hit the eye on center, they transmit all of their energy
to it and none to the surrounding bones. This type of impact frequently
causes an explosive eye rupture, which has an extremely poor visual
prognosis. The small, fast, and hard paintball, golf ball, hockey
stick, and polo mallet are especially devastating.
Most eye injuries are caused by blunt objects larger
than the orbital opening. This is the most common type of eye injury
in assault, falls in the elderly, airbag impacts, and sports such
as baseball, basketball (hands and elbows), racket sports, and soccer
(the soccer ball). While these injuries are often mild and do not
usually involve rupture of the eye, they sometimes have serious
consequences such as retinal detachment, cataract, blow-out fracture
(fracture of the thin bone beneath the eye), or retinal scarring
leading to loss of central vision.
Most people do not realize that deformation of
the ball upon impact will allow most balls to penetrate smaller
areas than would be possible with the ball at rest. At a high impact,
the ball flattens and becomes more elastic so that a portion of
it can protrude into a small space. If the ball is larger than the
orbital opening, the forehead and the orbital rim will absorb part
of the impact, but some of it will reach the eye. This is how a
soccer ball or volleyball is capable of causing significant eye
injury.
A severe blow to the head from, for example, a
baseball can indirectly injure the eyes, optic nerves, or visual
pathways. This may result in temporary or even permanent vision
loss.
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Note that the eyewear recommendations under 2 and 3 below are up
to date as of Fall 1996, but are subject to change as eyewear materials
and designs continue to be improved.
- Always use seat/shoulder
belts and infant car seats.
- Wear polycarbonate
lenses or eye protectors.
- Wear a protector
appropriate to the risk.
- Take special care
to protect your eyes.
- Protect your eyes
if you are one-eyed.
Even if you are only driving half a block or moving your car to
a different space, buckle up! Eye injuries are common in automobile
accidents, even slow-speed accidents. People not wearing seatbelts
have been blinded in both eyes by impact with the steering wheel
or dashboard while being otherwise uninjured.
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Ask for polycarbonate when you are buying sunglasses or an eye protector,
and if you wear prescription lenses, ask your eye care provider
to prescribe polycarbonate. At present, four materials are commonly
used in eyeglass lenses: glass, CR-39 plastic, high index plastic,
and polycarbonate plastic. Polycarbonate (sometimes known by the
trade name Lexan) is the most impact-resistant of these and should
always be used in eyewear unless the greater scratch resistance
of glass is essential. Although no material can totally eliminate
the risk of injury from a shattered lens, polycarbonate's high impact
resistance greatly reduces the risk. In tests of comparative impact
resistance of lenses, only polycarbonate lenses could withstand
impacts from an airgun pellet, golf ball, tennis ball. lacrosse
ball, or baseball at speeds normal for these sports with skilled
players. The safest, most rigid polycarbonate lens, recommended
for industrial use and shopwork, is the industrial safety lens,
3 mm thick at the center, specified by the American National Standards
Institute (the ANSI Z87 3-mm polycarbonate industrial lens). For
streetwear, a good choice is the ANSI Z80 streetwear polycarbonate
lens with a 1.5-mm center thickness. This lens is hard to break,
but it does deform more than the 3-mm lens with severe impact, such
as with a baseball. Even the ANSI Z80 1.0-mm-center-thick polycarbonate
streetwear lens is stronger than the ANSI Z87 glass or CR-39 industrial
safety lens. However, the 1.0 mm lens is too flexible for most sports
and can be dislodged from the frame at the time of impact.
For industrial and shop use, you should
ask for a 3-mm polycarbonate lens inserted into an ANSI Z87 frame
with side shields. Goggles or face shields may be required for some
industrial applications. A sunglass or spectacle lens could comply
with the ANSI Z80 or Z87 standard and still not have sufficient
impact resistance to the forces commonly encountered from airbags,
falls, industry, sports, or military activities. These standards
require that the lens withstand the impact of a steel ball of specified
size dropped from a specified height. A different approach to standard
setting is used by the American Society of Testing and Materials
(ASTM), whose standards are based on the impacts actually encountered
in the activities for which the standards are being set. ASTM F803
for racket sports and women's lacrosse tests for realistic impacts
with racket sport balls, rackets, and lacrosse balls, striking the
eyewear from various angles. ASTM F803 is currently the strictest
eyewear standard that applies to a protector for the eyes only (as
opposed to a protector integrated with a helmet or face shield)
and is your best choice for high-impact sports. It should be specified
when high sports impacts are expected. Eye protectors for youth
baseball fielders and women's field hockey are in the process of
being added to ASTM F803.
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The choice of a protective device should be based on the nature
and severity of the risk.
For impacts from large objects that can injure
the face and head as well as the eye, your best choice is an integrated
face mask/helmet system, which serves to spread the time duration
and area of impact and absorb a large part of the energy. Many activities
in the military, industry (chain sawing, fire fighting, policing
riots), and sports (hockey, football, lacrosse, youth baseball batting,
downhill ski racing, motor sports) involve huge collision forces,
which may shatter facial bones or injure the brain, and often cause
eye injuries. The helmet must be specific to the impacts expected
in the activity - a lacrosse helmet is ineffective for motorcycling;
a football player would not get proper protection from an equestrian
helmet. The attached face protector should withstand the likely
impact-a policeman on the bomb squad would not feel secure with
a football face shield.
For activities with potential brain
injury forces, but less risk for eye and face injury, a helmet plus
separate eye protector is a good choice. The helmet is essential,
while eye protection is usually desirable but may be separate. All
eyewear should be poly-carbonate, but impact resistance may not
be the only requirement. The jockey and the mountain bicycle racer
require protection from mud and dirt splatter, with the ability
to peel off mud splatters without slowing down. The cyclist and
slalom ski racer need sun and wind protection. The polo player who
prefers separate eye protection needs a protector which will not
shatter from the impact of a mallet or ball. The construction worker
in the figure shown and the combat soldier have different requirements
for protective helmets and eyewear.
Some activities have a high risk of eye and face
injuries but sufficiently low energy levels so that the forces can
be absorbed by the facial bones and forehead through the Peripheral
padding of a face-supported eye and face protector. Effective face-mounted
protectors are available for welding, lathe and table saw use, fencing,
baseball catching, and paintball. The face-supported ice hockey
goalie mask is ineffective and should not be used.
Activities such as grinding, woodworking, and the
racket sports have high eye injury risk but little risk for brain
and face injury, so that an eye protector alone is sufficient. An
industrial eye protector should meet ANSI Z87 requirements and those
for sports ASTM F803.
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If you have a condition that makes the eye more prone to injury.
Extreme nearsightedness, a previous injury or infection, or prior
surgery may make your eye vulnerable to injury or even rupture by
a lesser force than would be necessary to injure the normal eye.
Any incision in the cornea (front covering of the eye) results in
a scar that does not have the same tensile strength as the original
cornea. Think long and hard before having such purely cosmetic eye
surgery as radial keratotomy. If you have a vulnerable eye, wear
eye protection.
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You don't need to have lost an eye to be functionally one-eyed.
A child is functionally one-eyed when the best corrected vision
in the poorer eye is less than 20/40, and an adult is functionally
one-eyed who feels that the level of vision in the poorer eye would
interfere with his or her life or livelihood if the better eye were
lost.
For daily wear if you are one-eyed, you should
protect the good eye by wearing polycarbonate lenses (which can
be plano, i.e. nonprescription, if you do not otherwise need glasses).
Lenses should be mounted in a sturdy streetwear frame that achieves
a good compromise between safety and cosmetic acceptance. Always
wear proper safety eyewear for industrial and sports activities.
Eye protection works.
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