Persistent pupillary membrane (PPM) is a condition of the

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

involving remnants of a fetal membrane that persist as strands of tissue crossing the

pupil The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company. It appears black becau ...

. The pupillary membrane in

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s exists in the

fetus A fetus or foetus (; : fetuses, foetuses, rarely feti or foeti) is the unborn offspring of a viviparous animal that develops from an embryo. Following the embryonic development, embryonic stage, the fetal stage of development takes place. Pren ...

as a source of blood supply for the

lens A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...

. It normally atrophies from the time of birth to the age of four to eight weeks. PPM occurs when this atrophy is incomplete. It generally does not cause any symptoms. The strands can connect to the

cornea The cornea is the transparency (optics), transparent front part of the eyeball which covers the Iris (anatomy), iris, pupil, and Anterior chamber of eyeball, anterior chamber. Along with the anterior chamber and Lens (anatomy), lens, the cornea ...

or lens, but most commonly to other parts of the iris. Attachment to the cornea can cause small corneal opacities, while attachment to the lens can cause small

cataract A cataract is a cloudy area in the lens (anatomy), lens of the eye that leads to a visual impairment, decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or ...

s. Using topical

atropine Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically give ...

to dilate the pupil may help break down PPMs. In dogs, PPM is inherited in the

Basenji The Basenji () is a breed of hunting dog created from stock that originated in Central Africa, including in the Republic of the Congo and other adjacent tropical African countries. The Fédération Cynologique Internationale places the Basenji ...

but can occur in other breeds such as the

Pembroke Welsh Corgi The Pembroke Welsh Corgi (; Welsh for "dwarf dog") is a cattle herding dog breed that originated in Pembrokeshire, Wales. The name ''Corgi'' is of Welsh origin, and is a compound of the words and (mutated to ), meaning "dwarf" and "dog", r ...

Chow Chow The Chow Chow is a spitz-type of dog breed originally from Northern China. The Chow Chow is a sturdily built dog, square in profile, with a broad skull and small, triangular, erect ears with rounded tips. The breed is known for a very dense do ...

Mastiff A mastiff is a large and powerful Dog type, type of dog. Mastiffs are among the largest dogs, and typically have a short Coat (dog), coat, a long low-set tail and large feet; the skull is large and bulky, the muzzle broad and short (brachycephal ...

, and

English Cocker Spaniel The English Cocker Spaniel is a breed of gun dog. It is noteworthy for producing one of the most varied numbers of pups in a litter among all dog breeds. The English Cocker Spaniel is an active, good-natured, sporting dog standing well up at ...

. It can also be observed in

cat The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...

s, and

cattle Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...

References

External links

Dog diseases Disorders of iris and ciliary body {{Veterinary-med-stub