1. Optic Nerve Hypoplasia (ONH) by Cynthia White-Botello
Diagnosis
All components of the nerve head are abnormally small, typically one-third to one-half normal size. Often the optic nerve is surrounded by a ring of visible sclera and annular pigmentation, the “double ring” sign. The inner ring is typically darker. Retinal vessel tortuosity or thinning may also be present.  Visual acuity ranges from 20/50 to no light perception but is usually 20/200 or better.  The eye doctor can get a good estimate about the size of the optic nerves in a patient via an ophthalmoscope and MRI (magnetic Resonance Imaging). Many infants who are diagnosed with Optic Nerve Atrophy are, in fact, children with ONH.
What is Optic Nerve Hypoplasia?
Optic Nerve Hypoplasia (ONH) refers to the underdevelopment of the optic nerve during pregnancy (congenital). The dying back of optic nerve fibers as the child develops in utero is a natural process, and ONH may be an exaggeration of that process. ONH may occur infrequently in one eye (unilateral) but more commonly in both eyes (bilateral). ONH is not progressive, is not inherited, and cannot be cured. ONH is one of the three most common causes of visual impairment in children. (see ONH Fact Sheet)
Causes: In most cases there is no known cause. However, recent research suggests primiparity (a woman who has only one child) and young maternal age may be related. Drug and alcohol use during pregnancy has been refuted and heritability is rare (Dec 2012, Garcia-Filion, Bouchert). Gender, race and socioeconomic groups are all equivalently affected by ONH.
Characteristics
May occur by itself or along with neurological or hormonal abnormalities that may appearing prior to or during adolescence
May range from generalized loss of detailed vision in both central and peripheral fields (depressed visual fields) to subtle peripheral field loss.
Many patients have nystagmus and strabismus which can be associated with significant bilateral reduced visual acuity.
ONH is a stable condition. Visual function does not deteriorate with time, mild improvement in visual function may occur as the result of maturation processes of the brain. Reduced nystagmus may also occur over time.
Depth perception may be more severe if vision loss is severe.
Mild light sensitivity (photophobia) may occur.
Associated brain & hormonal abnormalities
Midline anomalies of the brain: including failure of the septum pellucidum and the corpus callosum to fully develop
Hormonal insufficiencies: thyroid, growth hormone, pituitary, adrenal, anti-diuretic hormone (ADH). Failure to thrive or feeding issues.
Visual & Instructional Considerations
Ongoing medical monitoring and comprehensive functional and educational assessment need to be considered in conjunction with other conditions.
Teachers may need to increase the size, contrast, and lighting of materials for a child who has nystagmus and bilateral severe visual loss because of generally depressed fields.
When a specific field loss is identified, materials need to be presented within the child's visual field. The child should be encouraged to turn his head to look for people and objects outside his visual field.
A child with ONH needs the opportunity to develop learned aspects of depth perception through fine and gross motor activities, including container play, nesting and stacking, ball tossing and rolling, pouring activities, and lots of practice with stairs, slides, foam wedges for crawling, and cardboard box play.
Light sensitivity can be minimized by adjusting lighting levels, wearing tinted lenses, and minimizing glare on surfaces.
A child who is easily distracted, frustrated, disorganized, and impulsive may be helped by predictable physical environments, dependable daily routines, and limited distractions.
Slowing the pace of activities and providing predictable transition routines may help reduce resistant and irritable behavior.
When a child does have feeding problems, parents and professionals need to agree on recommended strategies to create a positive feeding experience.
When a child has no functional vision, an approach that considers all the sensory needs for learning.
Evaluation by an instructor of Orientation and Mobility may be necessary
Fundus photograph of a normal optic nerve head and retina (on left), Optic Nerve Hypoplasia (on right) has a white rim of tissue around the smaller than usual optic nerve head.
Behavioral Associations
Sensory integration difficulties, including sensitive to certain textures, sights, sounds, smells, or other features of the environment. They might demonstrate a high pain tolerance and have limited awareness about their safety needs. Extreme food preferences are very common.
They might exhibit inappropriate and stereotyped behaviors, including hand-flapping, body-rocking, head-banging, biting or hitting parts of the body, and eye-pressing. These behaviors can be much more pervasive and/or difficult to extinguish in children with ONH.
Distractibility, impulsivity, and trouble focusing or staying on task.
Many children with ONH demonstrate autistic characteristics. They may have difficulty maintaining appropriate social interactions, may exhibit rigid adherence to routines, and perseverate on a specific and narrowly defined topic of interest.
Special narrowly-defined skills called “splinter” or even “savant” skills may be exhibited.
Global delays in overall development, as well as gross and fine motor skills are common.
Music is often a powerful motivator or for some has been their primary means of communication
The terms “septo-optic dysplasia” and “de Morsier’s syndrome” have historically been associated with ONH. These terms are now considered to be inaccurate and clinically misleading. (Garcia-Filion, PhD, MPH & Borchert, PhD, 2013)
Where to go for more information……
Parents & Families:
Optic Nerve Hypoplasia; A Guidebook for Parents
Focus Families: ONH/SOD Information, Education and Support
VI Specialists & Educators:
• Ophthalmic Pearls: Neuro-Ophthalmology Diagnosing Septo-Optic Dysplasia, By Philip M. Smith, MD, and Vivian Rismondo, MD, Edited By Ingrid U. Scott, MD, MPH, and Sharon Fekrat, MD Copyright © 2013 American Academy of Ophthalmology
• “Optic Nerve Hypoplasia” (ONH) L. E. Leguire Ph.D., MBA
Optic Nerve Hypoplasia Pediatric Visual Diagnosis Fact Sheet™ Blind Babies Foundation
References:
Adkins, A. (n.d.). Optic nerve hypoplasia. (2006). See/Hear Newsletter, 11(2), Retrieved from
Bernas-Pierce, M.Ed., J., Jacob, N., & Hoyt, MD, C. Blind Babies Foundation, (2010). Optic nerve hypoplasia: Pediatric visual diagnosis fact sheet. Retrieved from website:
Cummin, D. (2001). Sensory nerve for vision. Retrieved from notes m peripheral nerves.htm
 Flanagan, DC, M. (n.d.). The pituitary gland and the hypothalmus. Retrieved from
 Garcia-Filion, PhD, MPH, P., & Borchert, PhD, M. (n.d.). Optic nerve hypoplasia: A review of the epidemiology and clinical associations. (2013). Neurologic Ophthamology and Otology (RK Shin, Section Editor), 15(1), doi: D s
 Leguire PhD., MBA, L. E. (2013, ). Optic nerve hypoplasia (onh). Retrieved from
 Smith, MD, P., & Rismondo, MD, V. (n.d.). Ophthalmic pearls: Neuro-ophthamology. (2013). American Academy of Ophthamology, doi: