Hypertelorism - Causes, Symptoms, Diagnosis, and Treatment

What Is Hypertelorism?

Hypertelorism is the medical term for spacing between the orbits of the eyes wider than normal. It is also called orbital hypertelorism and ocular hypertelorism. It is not a disease or a condition but a feature of many genetic conditions or birth defects. Although it does not cause any symptoms, babies born with hypertelorism have eye sockets further apart than they should be, along with extra bone between their eyes, which fills in the additional space; surgery will help treat it. In rare cases, hypertelorism occurs on its own, but when it happens, it is referred to as isolated hypertelorism.

In normal development, the orbits develop laterally and move to their actual midline position. But in orbital hypertelorism, the eye sockets fail to move into their actual position, leading to wide-set eyes with extra bone between them.

How Is Hypertelorism Classified?

Hypertelorism is classified based on the measurement between the dacryon (a junction between the frontal, maxillary, and lacrimal bones). This is classified with the help of radiology and cannot be done clinically. The average interorbital distance for adults can range from 20 to 30 mm (millimeters). The following classification is used based on the intraorbital distance for hypertelorism in adults:

Tessier Classification:

• Normal - 20 to 30 mm ICD (inner canthal distance).

• First degree - 30 to 34 mm ICD.

• Second degree - 35 to 40 mm ICD.

• Third degree - greater than 40 mm ICD.

CT Scan Classification: Based on the orientation of orbital walls :

• Type I - Parallel medial orbital walls. This type is more common.

• Type II - The orbital wall is wedge-shaped posteriorly.

• Type III - It will be an oval at the widest dimension.

• Type IV - Anteriorly, it appears wedge-shaped. It is difficult to correct.

What Is the Cause of Hypertelorism?

Hypertelorism generally occurs due to an alteration in embryological facial development during the first four to eight weeks of an embryo’s development. The embryological precursor of the forehead and nose is the frontonasal prominence. During the normal development of this frontonasal prominence, the orbits will have a lateral movement followed by medial migration. But in some instances, due to an arrest in the frontonasal prominence of normal development, the primitive brain fills the space; this will limit the normal medial migration of the orbits and move them in a lateral position. Sometimes it can be detected on a prenatal ultrasound. But in most cases, healthcare professionals diagnose it shortly after birth. Several factors can interrupt the development of a baby. Some of the risks for hypertelorism in babies are birth defects and genetic disorders:

Birth Defects - Birth defects can affect how the child’s body physically works or looks. This can also lead to issues that are not visible. In some cases, the cause for birth defect cannot be identified, while in other it can be caused due to the following:

• Genetic and hereditary factors.

• Radiation exposure.

• Infections.

• Exposure to alcohol or recreational drugs or alcohol.

Genetic Disorders - It occur when a mutation (abnormal change in the gene) affects the genes or when the amount of genetic material is abnormal. Babies receive half their genes from each biological parent; if any of the parents have any disorder, the baby may inherit a gene mutation from their parents. Hypertelorism can be caused by various genetic conditions, including:

• DiGeorge syndrome.

• Noonan syndrome.

• Edwards syndrome.

• Crouzon syndrome.

• Apert syndrome.

• Diastrophic dysplasia.

• Neurofibromatosis type 1.

What Are the Symptoms of Hypertelorism?

The characteristic feature of hypertelorism is the wide-set eyes along with excessive bone present in between the eyes. Isolated hypertelorism is very rare. It may also present with other abnormalities like:

• The sunken appearance of the midface.

• Beaked nose.

• Teeth crowding.

• Underdeveloped maxilla.

• Vision problems due to shallow eye sockets.

• Mild to moderate intellectual disability.

• Hyperhidrosis (excessive sweating).

• Cleft palate.

• Cloverleaf skull shape.

• Low-set ears.

• Obesity.

How Is Hypertelorism Diagnosed?

Hypertelorism is often diagnosed soon after the birth or on an ultrasound done before the birth. There is no ideal measurement for the space between a person’s eyes. However, professionals usually use a few measurements to diagnose hypertelorism:

• Inner Canthal Distance: The distance between the inside edge (the side closest to the nose) of both eyes.

• Pupillary Distance: It is the distance between the centers of the pupils.

Children with hypertelorism have wider amounts of space on both their inner canthal distance and pupillary distance.

What Is the Treatment for Hypertelorism?

The treatment for hypertelorism is complex, and it is usually performed when the child is between five and seven years old. The surgery performed will be a type of reconstructive surgery, which provides the children with a more normal facial shape and adequate space between their eyes. Before planning the corrective surgery, the cause should be determined. Once the cause is identified, treatment decisions can be made for the best and long-term results for the child. Depending on the severity of the condition, several types of surgery can be performed, like the following:

• Extracranial Correction: For minor cases of orbital hypertelorism, this surgery is performed. This surgery is performed without touching the inner side of the skull, and the surgeon brings closer the bones of the inner portions of the eye sockets and nose.

• Intracranial Correction: This is performed for more pronounced cases of hypertelorism. This surgery is performed by a neurosurgeon and plastic surgeon working together. In the surgery, an incision is made from ear to ear. The forehead is removed temporarily, after which the brain is retracted. Dissection is made at the eye sockets and moved along with the eyes to the middle of the face. Then excess bone is removed. Other areas of the displaced face are also moved at this time. Then soft tissue is redraped.

• Box Osteotomy: In this technique, the extra bone and the skin above the child’s nose are removed, and the eye sockets are reshaped into that space.

• Facial Bipartition: This surgery removes a piece of bone in the shape of an upside-down triangle from the space between the eyes. The space between the eyes is then closed by rotating the upper face inward, so the eyes are closer together.

Conclusion:

Hypertelorism is a developmental abnormality in which the orbits are spaced more widely than normal. It is not a disease or a disorder but is characteristic of many different conditions. Isolated hypertelorism will not affect the health and development of a child. Treatment will help in correcting this condition. There are different types of surgery that will help in correcting hypertelorism.