What is Optic Nerve Atrophy?
Optic nerve atrophy is a morphologic description of a pale looking optic nerve when there has been a loss of volume of the optic nerve tissue. In adults there is often a definite event resulting in optic nerve atrophy, whereas in children more workup is required to identify the cause of optic nerve atrophy.
What causes Optic Nerve Atrophy?
Loss of retinal gangion cell axons (fibres transmitting vision signals from the retina to the brain) will result in optic nerve atrophy. This is due to the death of retinal cells such as in the late stage of retinal dystrophy, optic nerve inflammation or from trauma. Optic nerve atrophy can arise from compression of the optic nerve from raised intracranial pressure (hydrocephalus), a brain tumour or another central nervous system disease. Rarely, optic nerve atrophy can occur as resut of genetic abnormalities such as in dominant optic atrophy or recessive optic nerve atrophy.
What are the symptoms of Optic Nerve Atrophy?
Loss of vision, loss of colour vision, or loss of visual field are typical symptoms of optic nerve atrophy. However it may be asymptomatic in the early stages of the disease or present as ‘reading difficulties’ at school.
How is Optic Nerve Atrophy diagnosed?
The diagnosis is easily established when a pale looking optic nerve is documented on clinical examination in the context of visual loss. In children, the cause of the optic nerve atrophy needs to be investigated in almost all cases.
How is Optic Nerve Atrophy treated?
Treatment of optic nerve atrophy relies on identifying and treating the cause of the optic nerve atrophy. Neuroimaging of the optic nerve and brain are often required to establish the cause. Successful treatment of the underlying cause can often stop further damage to the optic nerve and preserve vision. Once optic nerve atrophy has occurred there are very limited treatment options. Seeking early consultation with an ophthalmologist or optometrist is vital.
Behaviours or conditions that might indicate Optic Nerve Atrophy
A wide range of acuity loss (how sharp and clear a person can see) exists. Prescription lenses will not improve the clarity of the young person’s vision.
- The infant may not give consistent, deliberate or prolonged facial regard.
- The infant may remain sensitive to bright light.
- The infant may find it challenging to focus and track moving objects.
- Visually guided reaching may not occur when developmentally expected.
- The infant may not recognise their parents across a room.
- Crawling may be delayed.
- Looking and reaching for objects for further investigation may be delayed or the infant may rely on sound to locate the object or voice to turn to familiar people.
For a child:
- May come in closer to gather detail of an object while playing.
- May miss details when looking at illustrations in books or when viewing photos or pictures.
- May want to come closer when trying to view information in the distance.
- May have difficulty recognising and discriminating print and pictures if they are too small, have fainter contrast levels and/or amongst visual clutter.
- May miss information in various visual fields (central and/or peripheral).
- May adopt a head turn if central field is affected in order to see the person or object.
- Colour vision may be affected which can make identification of some colours difficult.
What to do
- The young person should visit an optometrist or ophthalmologist to determine diagnosis and cause.
- A Functional Vision Assessment will review the infant, child or young person’s use of vision. This will include observations and assessments of how he/she uses vision in real life situations and for learning and access to Te Whāriki, the New Zealand Curriculum, the Blind and Low Vision Education Network, NZ (BLENNZ) Curriculum and the Expanded Core Curriculum.
- Adaptations or modifications to the environment and materials used may be required. Some of these can include lighting review, monitoring glare to reduce fatigue and maximise access and defining spaces to encourage play and movement.
- Strategies and suggestions for low and high tech devices later in life to assist the learner’s functional vision are also included in the functional vision assessment. Some of these strategies can include a review of print size, contrast levels and the effects of clutter.
- In some incidents when the optic nerve atrophy is significant, other literacy media may need to be assessed such as tactile literacy including braille. Tactile and aural environmental and material adaptations and modifications may also be required.
- A Developmental Orientation and Mobility assessment will assess how the infant, child or young person moves purposefully, safely and confidently in the environment and how they understand where they are in space and what is around them.