Peters anomaly is characterized by eye problems that occur in an area at the front part of the eye known as the anterior segment. The anterior segment consists of structures including the lens, the colored part (iris) of the eye, and the clear covering of the eye (cornea). During development of the eye, the elements of the anterior segment form separate structures. However, in Peters anomaly, development of the anterior segment is abnormal, leading to incomplete separation of the cornea from the iris or the lens. As a result, the cornea is cloudy (opaque), which causes blurred vision. The opaque area (opacity) of the cornea varies in size and intensity from a small, faint streak to a large, white cloudy area that covers the front surface of the eye. Additionally, the location of the opacity varies; the cloudiness may be at the center of the cornea or off-center. Large, centrally located opacities tend to cause poorer vision than smaller, off-center ones.
Mutations in the FOXC1, PAX6, PITX2, or CYP1B1 gene can cause Peters anomaly. The FOXC1, PAX6, and PITX2 genes are all members of a family called homeobox genes that direct the formation of many parts of the body. These three genes are involved in the development of the anterior segment of the eye. The CYP1B1 gene provides instructions for making an enzyme that is active in many tissues, including the eye. The enzyme's role in these tissues is unclear; it is likely involved in the development of the anterior segment.
The exact prevalence of Peters anomaly is unknown. This condition is one of a group of disorders known as congenital corneal opacities, which affect 3 to 6 individuals per 100,000.
Most cases of Peters anomaly are sporadic, which means that they occur in people with no apparent history of the disorder in their family. In many of these sporadic cases the genetic cause of the condition is unknown. However, some of these cases are caused by a new mutation in one of the previously mentioned genes or by the inheritance of a mutation from unaffected parents. In rare cases, the condition (or related eye disorders) has been reported to occur in multiple members of the same family.
Published Date: January 01, 2014Published By: National Institutes of Health