The oldest known lens was found in the ruins of the ancient Mesopotamian city of Nineveh and was made from polished rock crystal. The Greek playwright Aristophanes mentions the use of such a lens to burn holes in parchment in one of his plays. Allegedly, Pliny the physician used a similar lens to cauterize wounds. A thousand years later monks started using "reading stones" which were sliced off sections of polished quartz spheres. Sometime in the latter half of the 1200s the monks put these reading stones up on their noses in what today we would recognize as spectacles.
It was in Venice, Italy, where glassmaking was (and still is) an art, that convex reading and magnifying glasses were refined. About three hundred years later, concave lenses were used to help the near-sighted Pope Leo the 10th. He apparently wore his special spectacles to aid him while hunting. It took just about three hundred more years for bifocals to be invented by America's own Benjamin Franklin.
It was in the mid 1800s that a protective lens was made to fit directly over the eyeball of a man who had lost his eyelid from skin cancer. This first "contact lens" protected his eye from drying out, which would have resulted in blindness. Over the next 150 years, contact lenses came into commercial use and moved from blown, to ground, to molded glass lenses and then to a whole variety of hard, then soft, plastic lenses.
The knowledge of refracting light with lenses has, more recently, brought us to correct vision by surgically altering the shape of the cornea with laser beams. Where will we go next?
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​The shoulder is an elegant piece of machinery that can move and rotate in more directions than any other joint in the body. However, with such freedom comes less stability and greater risk of injury. The upper arm bone (humerus) and the shoulder blade (scapula) make a ball-and-socket type of joint. The ball is held into the socket by a network of rotator-cuff of muscles, tendons, ligaments, and a rim of cartilage.  This whole shoulder-joint-muscle system is attached to the chest and body by the collar bone (clavicle). Despite its marvelous engineering and design, humans will over-stretch and over-use their shoulders and injuries will happen.
 
Mr. AB had fallen off a tractor and dislocated his right shoulder when he was in his 30’s. He has been active as a farmer for more than 50 years, but over the last five months he’s noticed a gradually worsening pain in his shoulder and difficulty shoveling grain. Eventually, he told his wife he just couldn’t take it any longer and she made him an appointment to see me.
 
This patient came to my office like many farmers come to the doctor: reluctantly. I’m glad that he did. A number of medical problems can masquerade as shoulder pain, and some of them are quite dangerous. It was critical that I first take a careful medical history and perform a detailed exam before I went any further. I discovered that the pain was not related to exertion and relieved by rest, like that from heart trouble. It did not radiate below the elbow and did not have associated neck pain, like one would see with neck-spine nerve trouble. It was not made better by eating, like that from peptic ulcer problems. It was not made worse by a big and fatty meal, which would indicate gall bladder stones. Finally, it was not related to breathing and there was no fever, signs that would indicate pneumonia. Mr. AB’s pain was clearly made worse with movement of the shoulder and nothing else.
 
When his shirt was off, I noted both shoulders were symmetrical. With thumbs down and arms outstretched, it hurt as he raised his right arm. When I bent that arm at the elbow and rotated it downward, he winced with protest. His symptoms were the picture of inflamed, swollen, and tender structures rubbing while trying to pass under a tight arch of bone and ligament.
 
Mr. AB went to physical therapy, hired someone else to shovel, and rested his shoulder. Over time, his injury healed, and the pain went away. We take for granted the elegant engineering and design of the human shoulder.
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