This is the skin-crawling moment hikers perform impromptu eye surgery to remove a leech from their friend's eye.

The group had to briefly stop their activity when one of them experienced pain in his right eye during heavy rain on a mountain trail in Kamphaeng Phet, Thailand, on October 21.

Footage shows the man kneeling on the ground with his head tilted back while his companion uses a cotton swab to remove the small blood-sucking creature from his eye.

Moments later, they successfully extracted the parasite.

Leeches are predatory worms. Although their bites are mostly harmless, they can cause bleeding, bruising, itching, burning, irritation, and redness in the affected area. They are commonly found on the ground or in low foliage in wet forests.

Removing a leech is simple but requires a careful approach to avoid infection or injury as pulling them can cause its mouthparts to remain embedded in the human skin.