Peters anomaly

The cornea is located in the front part of the eye and is essentially the eye’s window. Under normal conditions, the cornea is completely transparent due to the large number of fibres that form it and the absence of blood vessels. This feature, together with the refractive power of the cornea and the lens, allows the images we see to be projected onto the retina, which is the part of the eye that actually “sees” the images.

Peters anomaly is a congenital error in the development of the eye that occurs between 10 and 16 weeks of gestation. It can affect one or both eyes and usually cannot be detected through prenatal screening.

It tends to be a one-off abnormality in a family, although sometimes it affects more than one family member. Genetic investigation of the family is important, since the genetic error (mutation) that causes it can be multiple; in other words, it does not only affect the eyes, but is also associated with mutations in other genes that affect other organs or systems, such as heart disease, deafness, learning difficulties, cleft lips and cleft palates. When this occurs, it is known as Peters-plus syndrome.

In this condition, the central part of the cornea is opaque (i.e. white). The fact that the central part of the cornea is not transparent always results in a loss of vision, whose severity increases with the degree of opacity If the abnormality affects both eyes, the child cannot recognise objects, although he or she may be able to perceive masses and recognise colours.

Although opacity tends to be the most obvious sign in these patients, corneal alteration occurs alongside other developmental abnormalities in the front part of the eye. It may also be associated with an increased risk of glaucoma (increased ocular pressure that can damage the optic nerve), nystagmus  nystagmus (involuntary eye movements), cataracts (a loss of transparency in the lens) and retinal detachment.

The condition varies in severity. In the most serious cases of underdevelopment, the eye is smaller (microphthalmia) and rudimentary.

The condition is usually detected by a paediatrician straight after birth, although Peters anomaly must be diagnosed by an ophthalmologist. It is important that a diagnosis be made as early as possible; sometimes a thorough eye examination under general anaesthetic is required.

Although central corneal opacity usually improves spontaneously during the first months of life, it is very difficult to predict the degree of vision the child will have.