What is Septo-Optic Dysplasia?
Septooptic dysplasia (SOD) is a condition of the nerves connecting the eye and the brain. In SOD, the eye nerve (optic nerve) is thin. The optic disc located at the back of the eye may also be abnormal.
There are three main abnormalities that are caused by this:
- Abnormal eye development – Occasionally one or both eyes may be abnormal or the nerves connecting the eyes to the brain may be thin and abnormal.
- Abnormal development of the front part of the brain (forebrain) – The septum pellucidum which is a partition that separates right and left cavities in the brain (ventricles) may be absent. The corpus callosum which is a bridge between the left and right sides of the front part of the brain may be thin and abnormal.
- Abnormal pituitary gland development – The pituitary gland produces a number of chemicals called hormones that control growth, puberty, thyroid and adrenal glands. Additionally, the back part of the pituitary produces a hormone called vasopressin which holds back water, so that patients do not become dehydrated.
In children and adults living with SOD, there is a possibility that they may be deficient in one or more hormones.
Diagnosis
The diagnosis of SOD is usually made in children but can also be late in adult life. In many children with abnormal eyesight, SOD is picked up by examination of the back of the eyes. SOD is also found on routine eye testing in babies born prematurely. Some babies with SOD pass excess water, a condition called AVP Deficiency (previously diabetes insipidus). They might havedehydration and high salt levels.
In older children, growth might be affected. These children may visit the doctor for short stature. Some children with SOD may enter puberty early. In others, excessive tiredness due to problems with thyroid and adrenal function may lead to the diagnosis of SOD. In milder forms of SOD, there may not be obvious hormone problems.
In most cases of SOD, a hormone specialist (endocrinologist)usually arranges investigations and treatment for the patient. A brain scan (called magnetic resonance image, MRI) is usually required to look at the eye nerve and the pituitary gland in the brain. Special hormone blood tests may be required to look for hormone deficiencies.
Treatment
Treatment of SOD involves support for abnormal eyesight and replacement of hormone deficiencies. Some patients have poor eyesightand may be blindto require significant sight loss support. Others may require glasses to improve their eyesight.
Following hormone investigations, replacements are given, where needed. For example, desmopressin is given to those with diabetes insipidus, hydrocortisone is given to those with adrenal insufficiency and growth hormone injections are given to those with growth hormone deficiency. In children with early puberty, an injection to pause puberty may be considered.Hormone replacements are usually monitored by endocrinologists and specialist nurses, working closely with patients.
Some patients living with SOD may not have an identified hormone problem at diagnosis. In such patients, a period of follow-up is helpful through childhood and puberty to check for problems that might come later.
