Messages about “Pupula Duplex” along with some strange pictures keep circulating now and then, claiming it to be a rare eye condition, where a person has two irises and two pupils in one eye.
Hoax or Fact:
Pupula Duplex is a Latin term which means double pupil, and is thought to be a condition in which a person develops two irises, corneas and retinas on the same eyeball of each eye. It is often referred as Double Iris and also as "Evil Eye." Let us examine whether this strange eye condition is fact or simply a hoax.
Pictures and messages about this Pupula Duplex came into limelight after Ripley's Believe It or Not featured such a picture of Liu Ch'ung, a Chinese Minister of State in 995 A.D., who was supposedly born with double pupils in each eye. A wax rendition of the man's unusual eye condition is also included in Louis Tussaud's Palace of Wax. It is also said that in 1931, Robert Ripley personally met a double-eyed man in Mills, Kentucky.
An eye condition called Pupula Duplex does not exist in official medical literature. In some ancient historical records, it is said that some Chinese rulers like Xiang Yu, a military leader during the late Qin Dynasty, as well as Shun and Duke Wen of Jin have suffered from this double pupil condition. Xiang Yu was a tall person who possessed unusual physical strength and was seen as an extraordinary person because his unique double pupil was a mark of a king or sage in Chinese tradition. The Chinese traditional thinking supposed that the Man who has double pupils would be doomed to be ruler or king. However, the exact eye condition of those rulers is not clear. The ancient writers in fact referred to it as the “Evil Eye.”
In a 1918 book titled 'The Pupula Duplex and Other Tokens of an “Evil Eye” in the Light of Ophthalmology,' writer Walton Brooks McDaniel considered Double Pupil a Superstition and probably there is no such thing among human beings. He suggested that a sphincter muscle in pupil of one eye, which enables it to contract and dilate, may sometimes give an appearance and impression to an ancient man that there existed two pupils.
So it is unclear exactly how the term Pupula Duplex was originally referred. There isn't much evidence to support that such a condition exists in humans. There is a possibility that the Ripley's depiction of Liu Ch'ung with two pupils in his two eyes could be inaccurate, or it possibly relates to some other related eye condition like Polycoria. Polycoria is an extremely rare pathological condition of the eye characterized by more than one pupillary opening in the (one) iris (shown in last picture in Image Gallery). It should also be noted that the concept of Pupula Duplex is often portrayed in mythological and science fiction literature.
With the available facts, credible hypothesis and lack of enough evidence, the condition of 'Pupula Duplex', where a person develops two irises, corneas and retinas on the same eyeball of each eye is possibly hoax. For any such thing to occur, perhaps an extremely rare genetic defect or mutation should occur, and even if that happens, the possibility of normal vision is not warranted.