The Five Senses and Beyond: The Encyclopedia of Perception - Jennifer L. Hellier 2017

Anophthalmia

Anophthalmia is a rare disorder in which a child is born without an eye or eyes. The absence of both eyes is more common. It is characterized by a complete lack of ocular tissue, and affected children typically have small eye sockets. This disorder develops during pregnancy and can occur along with other birth defects or by itself. It is believed to occur during development, resulting when the anterior neural tube fails to develop. There are many possible causes of anophthalmia, but many times the exact cause is unknown. Possible causes include mutations, both genetic and random, abnormalities of the chromosomes, and environmental factors such as drugs, radiation, and chemicals. The National Eye Institute reported an occurrence rate of 0.18 per 10,000 births in the United States (National Eye Institute, 2009).

Types

There are three classifications of anophthalmia: primary, secondary, and degenerative. In primary anophthalmia, the part of the brain responsible in forming the eye fails, resulting in no eye tissue whatsoever. In secondary anophthalmia, some eye tissue or very small eyes were present as the eye started developing but stopped developing for unknown reasons. In degenerative anophthalmia, the eye began forming, but at some point degenerated for unknown reasons. One explanation for this could be a lack of eye blood supply (Verma & Fitzpatrick, 2007).

Diagnosis

Anophthalmia can be diagnosed in several ways. A prenatal diagnosis can be made using a transvaginal ultrasound. After the baby is born, imaging using CT (computed tomography) and/or MRI (magnetic resonance imaging) of the head and eye sockets, physical examination of the eye sockets and surrounding areas, genetic testing, and ultrasound can all be used to make a diagnosis. Some of the physical characteristics, both of the eyes and generally, of children born with anophthalmia include absence of extraocular muscles, deformed eyelids, possible absence of the lacrimal glands, cleft lip or palate, possible hearing loss, and some irregularities of the heart.

Treatment

The treatment for anophthalmia focuses on treating the bony growth of the child’s face. The eye sockets play an important role in the bony and soft tissue growth and development of the face. Without proper treatment, the bones in the face will not grow properly and will lead to facial deformity. A child’s face grows at a fast rate, so treatment must be started as soon as possible. Treatment involves the use of conformers, which are plastic devices that are placed in the child’s eye sockets to help the bones in the face to develop correctly. Conformers enlarge the orbit and assist the face in developing to normal proportions. They also help to stimulate bone growth. As a child grows and develops, he or she will need different sized conformers. The number of conformers depends on each individual child, as no child grows at the same rate. Once the child is old enough and growth is maintained, a prosthetic eye may be used. This can help with overall appearances.

A child born with anophthalmia will need to see many different doctors for different treatments and overall care. The doctors will most likely include an ophthalmologist, an ocularist, and an oculoplastic surgeon. Surgical treatment may be recommended in some cases. Surgical procedures may include placement of inflatable expanders, eyelid surgery, or surgery for the eye sockets. Other treatments will include early and special intervention programs to help the child cope and learn to deal without vision, or limited vision. The first few years of a child’s life are critical for development. Children with anophthalmia may experience developmental delays and may have learning difficulties or behavioral issues.

Risk Factors

Genetics may play a role in anophthalmia. Genetic testing may be a helpful diagnostic tool. Currently, research is being performed to help identify which genes are involved in eye development. Many genes have been identified that play a role, and it has been shown that changes, or mutations, can cause atypical eye development. Many times, there is no family history of anophthalmia. One syndrome that has been described is sometimes associated with anophthalmia. It is known as SOX2 (SRY [Sex Determining Region Y]-Box 2) syndrome, and people who have this syndrome are often born with anophthalmia. It has also been shown that 10—15 percent of people with anophthalmia affecting both of their eyes have SOX2 syndrome (Genetics Home Reference, 2016). SOX2 syndrome is autosomal dominant, but many times the disorder is caused by a new mutation and is not inherited. People with SOX2 syndrome may have other problems associated with the syndrome, other than anophthalmia. These can include seizures, a blocked esophagus, delayed growth, and genital abnormalities, which occur most often in males.

Shannen McNamara

See also: Blindness; Microphthalmia; National Organization for Rare Disorders; Optic Nerve; Visual System

Further Reading

Genetics Home Reference. (2016). SOX2 anophthalmia syndrome. Retrieved from http://ghr.nlm.nih.gov/condition/sox2-anophthalmia-syndrome

International Children’s Anophthalmia Network (ICAN). (n.d.). General information. Retrieved from http://www.anophthalmia.org/general_information/

National Eye Institute (NEI). (2009). Anophthalmia and microphthalmia. Retrieved from https://nei.nih.gov/health/anoph

Verma, Amit S., and David R. Fitzpatrick. (2007). Anophthalmia and microphthalmia. Orphanet Journal of Rare Diseases, 2, 47. http://dx.doi.org/10.1186/1750-1172-2-47