The most common eye injury I see in practice is caused by small metallic objects lodged in the eye. While these injuries can occur to anyone, they are most common in people who work in manufacturing, the building trades, and industries requiring outdoor work.
Most of these foreign bodies injure the external eye at the cornea. They are often “minor” compared to penetrating injuries, but nothing is ever minor when you are talking about a special sense organ like the eye. Human vision is easy to break, hard to fix, and irreplaceable. I hope this short article gives you some insight into this truth and, perhaps, inspires you to recommit to diligent protection of your eyes and vision.
The Cornea of the Eye is Particularly Vulnerable
The cornea is the clear lens in the front of the eye. It is particularly vulnerable to injury because it is a transparent body tissue and needs to remain transparent to function. Consider the following:
· Cornea transparency is created and maintained by a complex arrangement of tissue layers. The layers are packed so precisely that any gaps are too small to scatter light. As such, the cornea lets light pass right through like glass without significant scattering.
· Injury disrupts that complex arrangement and there is a resultant loss of this transparency. These disruptions heal in a way that often leaves residual haziness or scarring.
· Once the outermost cornea layer is damaged, it may never again adhere to its foundation with quite the same vigor. Normal things like opening your eyes after sleep or blinking can cause a repeated sloughing of this outer layer, which causes significant pain, light sensitivity, watering, and visual distortion.
The Effects on Vision of Corneal Haze and Scarring
Corneal scarring and haze make all the aspects of human vision worse. Here I mention a few:
· There is a loss of contrast. A cloudy lens cannot transfer a perfect image to the “film of the camera.” High contrast images become lower contrast images. Low contrast images may become impossible to see.
· Scarring leads to subtle changes in cornea curvature that cannot be corrected by glasses. These imperfections cause subtle aberrations in your vision. For example, lights will cause bigger starbursts and images can have shape distortions.
· Because cornea haze scatters light, it makes glare much worse, sometimes disabling.
· Depth perception is degraded. Depth perception comes from each eye seeing the same image from a different angle. Injury to one eye degrades one image and, thus, makes subtle differences in depth harder to see.
How to Avoid Cornea Foreign Bodies
· Wear safety glasses with appropriate frame, lenses, and side shields. Safety glasses with side shields removed are no longer safety glasses. So says OSHA.
· “Brush off” your hair and eyebrows before removing your safety glasses. Many foreign bodies “fall into” a person’s eye from hair and eyebrows after they remove safety glasses. Face downward, brush off, then remove glasses. While they don’t hit with force, these foreign bodies still cause problems.
· Don’t kid yourself. You won’t see or avoid debris generated by high-velocity tool. Properly manufactured and adjusted safety glasses are the only appropriate protection.
· Be aware of your surroundings. In addition to high-speed tools, hammers generate flying debris; windblown objects cause at least as many injuries as tools.
Nothing is minor when it comes to the human visual system. Guard your eyes like they’re easy to break, hard to fix, and irreplaceable. They are all three.
I am available for talks on eye safety and triage of eye injuries at no cost if you feel it would benefit your company and your employees.
Dr. Mark Kahrhoff
Complete Safety, LLC