Modern medicine has accomplished some incredible feats, including helping people to survive injuries and diseases that might have seemed impossible to survive a few decades ago.

Doctors and researchers have captured images of some of these cases, and we've rounded them up, along with other images of unusual symptoms and features of conditions.

Here's a look at five amazing images in medicine.

5 A fence pole through the head

This X-ray shows 28-year-old Las Vegas man Andrew Linn, who survived a 2010 car accident that pushed a 2-inch-thick metal fence pole through his mouth and out through the back of his neck, according to a report of his case in the Las Vegas Review-Journal.

Linn “was very calm and didn't appear in any pain,” surgeon Dr. Jay Coates, of University Medical Center, told the Review-Journal. The medical team at was able to remove the pole without damaging either of two major blood vessels — the carotid artery and jugular vein — in the neck region.

4 An accidental swallowing of a knife

This X-ray shows a knife that became stuck in a 30-year-old woman's esophagus and stomach, causing her “chest discomfort,” according to a report of her case.

The woman had previously had the eating disorder bulimia, and had inserted the knife into the back of her mouth in order to demonstrate that she had lost her gag reflex. But she laughed unexpectedly, and the knife fell into her body, according to Dr. Aida Venado and Dr. Sarah Prebil, of Emory University School of Medicine, who reported the woman's case in the New England Journal of Medicine in 2012.

Doctors were able to remove the knife in a procedure called an esophagogastroduodenoscopy, in which a small camera is used to view the esophagus. The woman recovered, and she was able to eat without complications, according to the report.

3 A hairy eyeball

This picture shows a mass called a “limbal dermoid” on the right eye of a 19-year-old man. Limbal dermoids are solid masses and frequently contain hair shafts.

The man had come to a clinic because he had discomfort when he blinked, and felt as though there was something in his eye, according to Dr. Ali Mahdavi Fard and Dr. Leili Pourafkari, of the Tabriz University of Medical Sciences in Iran, who reported his case in the New England Journal of Medicine in January.

He'd had the mass since birth, but it had gradually grown. In his left eye, he had 20/20 vision, but in the right eye, his vision was 20/60, according to the case report.

The man had the mass removed in surgery for cosmetic reasons, but his vision did not improve.

2 “Half-half” blisters

This image of unusual blisters on a 66-year-old man was captured at Leeds General Infirmary in England.

The blisters contained both clear pus and yellow fluid, and were found on the man's trunk, according to Dr.Michael O'Connell and Dr. Victoria Goulden, who reported the man's case in the New England Journal of Medicine in 2012.

After a biopsy, the man was diagnosed with a condition called subcorneal pustular dermatosis. A similar condition can be caused by drugs, but trigger in this man's case was unclear, according to the case report.

The man was treated with steroid medications and recovered.

1 Beer bottle in the colon

This X-ray was taken of an intoxicated 35-year-old man who went to an emergency room in Mexico with rectal bleeding and abdominal pain.

Doctors examined his abdomen and found a mass, but no signs of trauma. A rectal exam revealed a foreign body that could not be seen, so once the patient was well enough, he was sent to be X-rayed, according to Dr. Roberto Flores-Suarez and Dr.Jorge Reyes-del Valle, of the State Health Institute of Mexico, who reported the man's case in the New England Journal of Medicine in 2010.

The bottle was removed in surgery, and the man was treated with antibiotics and pain relievers. He eventually recovered.