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.
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.
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.
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.
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.
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.
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.