Optic Nerve Hypoplasia (ONH)
What is Optic Nerve Hypoplasia?
Optic nerve hypoplasia (ONH) is a congenital condition in which the optic nerve is underdeveloped in one eye (unilateral) or both (bilateral).
Since you see things as your eyes receive impulses from the optic nerves, your vision function is diminished when optic nerves are underdeveloped, as in the case of ONH.
ONH patients may also have nystagmus, which is characterized by involuntary, abnormal eye movements. When you have ONH, you may barely receive light in one, or both of your eyes, and the amount of disability can range from minor to profound.
Prevalence of Optic Nerve Hypoplasia
- Researchers believe that ONH affects females and males at the same rate.
- The prevalence of this disease is approximately 1 in 10,000 children, according to the National Organization of Rare Diseases.
- ONH accounts for approximately 25% of vision loss in infants, according to a report from the Oman Journal of Ophthalmology.
Signs and Symptoms
While optic nerve hypoplasia is manifested at the time of birth, symptoms might not be evident until the infant reaches adolescence. Vision disturbance in one or both eyes is common.
- Lack of visual detail and general blurring of vision
- Unaware of objects in the periphery
- Mild sensitivity to light
- Lack of depth perception
- Experience delays in acquiring skills to coordinate their muscular and mental activity
- Squint, lower their head, or refuse to participate in outdoor activities to avoid light if they have photophobia
- Have very limited food preferences, and could exhibit excessive lip smacking while eating
The fundamental cause of optic nerve hypoplasia is not yet understood, according to the National Organization of Rare Diseases, which noted that, “in most cases, the disorder appears to occur randomly for unknown reasons.” However, researchers do know that ONH is a congenital condition.
- In many cases, children with ONH are also diagnosed with autism.
- Midline anomalies of the brain are common, such as cerebral atrophy and septo optic dysplasia.
- There may be hormonal insufficiencies, for example in the pituitary and thyroid glands.
Laboratory or radiographic tests cannot currently detect ONH. It can only be diagnosed through direct eye examination by an ophthalmologist.
MRI studies are common for people suspected of having ONH. Optical coherence tomography (OCT) is another common tool for detecting ONH.
One sign of having ONH is an optic disk that is smaller than average. The optic disk is the part of the eye responsible for the “blind spot” where there are no light-detecting cells, because it is where retina nerve fibers meet to create the optic nerve, connecting from the back of the eye to the brain. An eye doctor can determine the size of a patient’s optic disc by investigating with an ophthalmoscope.
Corpus Callosum or Septum Pellucidum
A report from the Children’s Hospital of Los Angeles indicates that patients with ONH sometimes lack a corpus callosum (or have an abnormal one), which connects the left and right sides of the brain. Or, patients may have a malformed septum pellucidum, which is a membrane that connects lateral ventricles in the brain. Neither of these defects will affect the function of the brain, but they do sometimes occur with ONH.
Low Vision Apps
Your smartphone can be a handy resource by installing low vision apps, and the operating system may already come with options for disabled individuals.
Strategies for Children with ONH
- Encourage fine and gross motor activities to help them develop and learn aspects of depth perception, such as ball throwing, pouring, and stacking.
- Minimize effects of light sensitivity through adjusting lighting levels and reducing surface glare.
- Consider all underlying behavioural conditions when developing an education plan.
- Consult professionals to help create a positive feeding experience for those with limited food preferences.
Community Resources and Support Groups
Feeling isolated is common when dealing with a medical condition such as ONH. You can improve the situation by finding support systems and sharing stories with others who are going through similar difficulties.
- FB – Optic Nerve Hypoplasia and Septo Optic Dysplasia Support Group: supports parents, family members, and guardians of children who have ONH or SOD
- FOCUS Families: provides information, education, and support to those affected by ONH and SOD worldwide
- ONH Consulting: provides direct and personalized guidance, support and advocacy services to families of children and youth with ONH
- One Small Voice Foundation: strives to give a voice to all children with ONH
- FamilyConnect: gives parents of visually impaired children a place to support each other, share stories and concerns, and link to local resources
Latest Research and Publications
New information about ONH is published every day.
- Genetic and Rare Diseases Information Center: GARD Information Specialists provide current, reliable, and easy to understand information about rare or genetic diseases in English or Spanish
- MAGIC Foundation: publishes brochures on a number of endocrine disorders written by globally recognized thought leaders and researchers on each topic
- National Federation of the Blind: creates and distributes several publications and audio reports to inform about the true nature of blindness and issues of interest to the blind
- Blind Children’s Center: sells a straight-forward, easy to understand booklet that shares educators’ and therapists’ observations and advice for parents of children with ONH
- American Foundation for the Blind: provides publications with relevant and practical resources that support teaching, research, independent living, and the delivery of critical services for people with vision loss
Available Assistive Technology
eSight eyewear is a valuable option for those diagnosed with ONH.
The eSight 3 is a low vision eyewear device that stimulates synaptic activity from the remaining photoreceptor function of its users’ eyes. Many successful eSight users live with ONH, such as Nick Roberts, who experienced 20/20 vision for the first time in his life while using eSight, and now uses it to read fine-print books required for his criminal justice studies program, scan menus in restaurants, and watch his favourite hockey team, the Florida Panthers.
The eSight has a cutting edge camera, smart algorithms and high resolution screens. It is clinically validated to result in enhanced vision of up to 7 lines on a doctor’s eye chart, while simultaneously boasting superior mobility for its users.
As well, for those with ONH who experience photophobia, eSight lets users adjust both the brightness and contrast of the screens, which means it is well-suited for people with light sensitivity.
When was the first time ONH was mentioned in scientific literature?
ONH was first described in medical literature in 1884.
Is ONH genetic?
No, ONH is not inherited.
Does ONH have a cure?
Currently, there is no cure for ONH; however, those with ONH could still benefit from eyesight-enhancing eyewear such as eSight.
Is ONH progressive?
ONH is not progressive.
Is it true that all mothers of children with ONH used drugs during their pregnancy?
No, this is a myth, according to the Texas School for the Blind and Visually Impaired.