Iris melanocytes may be observed on the anterior lens capsule forming "pigment stars" or "chicken tracks". The central portion may attach to the anterior lens capsule or float with free edges. The peripheral portion always inserts into the iris collarette. Most of the times, it can be seen as single or several lacy strands that partially bridge the pupil. Slit lamp appearance of PPM can be variable. PPMs are usually asymptomatic except for cases with a pupillary opening of <1.5 mm in which decreased retinal illumination and diffraction results in impaired vision. They are congenital in origin, do not affect vision and may be nonaxial. Pure capsular opacities associated with persistent pupillary membranes or epicapsular stars are very rare. Type 3 membranes, which are attached to the cornea, typically occur in Axenfeld-Rieger syndrome.These pigmented stars of the anterior lens capsule are often called “chicken tracks”. In a sub-variant of type 2, pigmented dendritic iris stromal melanocytes, singly and in clumps, are situated aberrantly on the anterior lens capsule. Type 2 membranes are iridolenticular adhesions.Type 1 membranes that are attached solely to the iris.There is no sex predilection and may present unilaterally or bilaterally.ĭuke-Elder has Classified PPM into several variants They are more common in premature babies. The remnants of pupillary membrane are seen in about 95% of neonates and 20% of adults. Postnatal PPM undergoes considerable atrophy in the first year of life. There is evidence that intrauterine stress, particularly from chronic maternal hypertension, may accelerate the disappearance of these membranes. A failure of resorption of pupillary membrane leads to persistent pupillary membrane. The pupillary membrane undergoes regression aided by macrophage phagocytosis in the sixth month and disappears completely by the eighth month of gestation. ![]() The dorsal posterior hyaloid vessels anastomose with the network of vessels in the pupillary membrane to form tunica vasculosa lentis which provides nutrition to the lens. It is composed of vessels derived from anterior ciliary arteries and mesenchyme and lies ventral to the lens. Embryologically, the iris forms as a solid sheet of mesodermal tissue known as the pupillary membrane. Persistent pupillary membrane represents remnants of anterior tunica vasculosa lentis. In rare cases, dense membranes can persist and obscure the pupil, causing amblyopia.Īlthough familial forms have been reported, most cases are sporadic in nature. They are usually asymptomatic and of no functional significance. ![]() ![]() It represents remnants of anterior tunica vasculosa lentis and appears as strands of connective tissue bridging the pupillary area. Persistent pupillary membrane(PPM) is a frequently encountered congenital anomaly.
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