Amblyopia and visual development

Amblyopia And Visual Development

Amblyopia is a neuro-developmental condition in which vision does not develop adequately in one eye.  

In the early years of life, there is a constant process occurring in our brains where neurons, or nerve cells, are forming connections with other neurons.  This describes the basic units of information processing.

Every baby is born with approximately 100 billion neurons. The number of possible connections or synapses formed between neurons in an infant’s brain is amazing

  • At birth, a baby has 50 trillion connections or synapses
  • In the first three months of life, the synapses multiply more than 20 times
  • By one year the brain has 1,000 trillion synapses

It is the development of these connections which allows us to see, hear, smell, taste and move.  

For example, the optic nerve of the eye has millions of connections with the visual cortex of the brain.  Just as the quality of the picture we see on a television screen relies on the signal from the antenna, the image processed by the brain is dependent upon the image received and transmitted by our eyes. 

Connections that are used regularly become stronger and more complex, those that are not used are “pruned” and eventually eliminated.  With lack of appropriate visual stimulation, the connections between the eye and the brain may fail to develop; as a result, the eye fails to develop the ability to see clearly, this is known as Amblyopia.

Any condition that affects normal visual development can cause Amblyopia

It can be caused by strabismus, which is an imbalance in the positioning of the two eyes. The presence of an eye turn has the potential to cause double vision.  As double vision is so disconcerting, the child’s brain overcomes this by ignoring the image seen by the turned eye (this is known as suppression).

Most children adapt well to seeing through one eye; because of this many parents are unaware of the problem until it is diagnosed during a thorough eye examination.

Amblyopia can also occur in eyes that are straight, but have significant or unequal refractive errors. Amblyopia can be caused when one eye is either more myopic (nearsighted); hyperopic (farsighted), or astigmatic (distorted image) than the other eye.  The affected eye does not receive proper visual stimulation; therefore, normal vision does not develop.

Amblyopia affects many areas of vision including the ability to see clearly. 

Recognising shapes and discriminating fine details and differences; focusing on close work and the ability to move the eyes in a fluid and precise manner; along with the ability to make accurate judgements of surrounding space are often affected.

The spatial effects of Amblyopia include poor depth perception, peripheral awareness, posture and balance. Confidence in climbing activities, playgrounds, steps and stairs, bike-riding, ball skills and road sense may be reduced.

In the classroom, the ability to see the board and small print will be more difficult.

Writing posture, neatness and page organization may be irregular.  Copying skills will often be slower and visual attention is more susceptible to being distracted. Eye movement and tracking skills are often less controlled, causing excessive head movement and leading to decreased fluency, along with problems keeping focus on a page covered in print.

Treatment of Amblyopia

The key to the management of amblyopia is identifying the condition as early as possible since neural pathways are more plastic or modifiable during the infant years.  It is important to institute therapy as early as possible, as the later therapy is implemented, the worse the prognosis.

Treating amblyopia requires the child to use the amblyopic or weaker eye. Common forms of amblyopia therapy include:

Spectacles

Assessment of eye health, as well as an accurate prescription, is essential to ascertain the long term chances of improvement, allowing your eye practitioner to identify the best treatment options.

A spectacle or contact lens prescription improves visual clarity to the optimum level.  This is the first step required to initiate a change in visual status.

Spectacles are also able to help and sometimes fully straighten a turned eye, especially if the child demonstrates a significant degree of hyperopia (long-sightedness).

Eye Patching

An opaque, adhesive or specific optical patch is worn over the stronger eye.  This therapy forces the child to use the amblyopic eye, thus stimulating the visual brain centres.  Eye patching is not an instant cure and is likely to go on for some months.  It is important to realise that in order for patching to be successful it needs to include activities that stimulate vision, not just passive viewing tasks such as watching TV.  This can include exercises to improve focusing, eye tracking, spatial awareness, and eye-coordination.

In pre-school children, it is more common to patch the stronger eye all day.  In school age children; good visual outcomes are achieved with two hours of patching per day, whilst performing activities to stimulate the weaker eye’s attention.  A schedule of five out of seven days per week is often very effective.

Atropine

Atropine is a drop used to blur the vision in the stronger eye so that the child is encouraged to use the amblyopic eye. Again this treatment works most effectively when it is used concurrently with vision therapy. Atropine can only be prescribed by a qualified practitioner.

The duration of any treatment can be weeks to months depending upon many factors such as the child’s age, the degree of vision impairment or whether the amblyopia is related to an eye turn.

Vivid Vision Therapy

Depending on the outcome of the results and the age of the child, additional vision therapy may be recommended.  The Vivid Vision therapy system uses a virtual reality environment to stimulate the amblyopic eye and to fine-tune vision development.

Your practitioner will discuss these options with you and advise which is the most appropriate for your child’s needs.

When your child’s Amblyopia is present

RIGHT EYE / LEFT EYE

It is recommended that the stronger eye (opposite to the Amblyopic eye, is patched for 2 hours per day.  Patching the stronger eye all day will not cause any harm, however, the incremental benefit of patching an eye for longer, may not be significant.  The stronger eye should be patched for five out of seven days per week, and the days off should be presented as a reward for doing such a good job.

A range of “thinking” activities should also be performed when the eye is patched below are GENERAL GUIDELINES

  • Improve lighting (natural or artificial), as well as the size, contrast, borders, colour and detail of any visual objects in the persons environment. e.g. mark path edges, steps, etc. with dark or contrast borders.
  • Utilise balls or toys with strong geometric patterns.
  • Use contrast for written tasks such as black or dark blue on white marker-boards, and white or yellow on black chalkboards.
  • Use large print books, large print playing cards and larger fonts for near tasks and computer activities.
  • Add distinct borders to the edge of worksheets (particularly to the left), this guides awareness of writing from left to right. Darkening page-lines in workbooks will also be of benefit.
  • Use strong colours and clearly demarcated shapes for threading, cutting and colouring.

Good Vision For Life

Good Vision for Life

Most of the important information required for everyday living is obtained through our eyes, yet only approximately 17% of the population have a comprehensive eye examination each year.

This figure is surprising given how important our eyesight is to everyday living.  Good vision is essential for driving, playing sports and fulfilling work and school tasks which is why it’s so important that children, teens and parents incorporate regular eye examinations into their general health regime.

During an eye examination an optometrist will assess your visual clarity while also looking for signs of possible eye conditions or disease.

Regular eye examinations can lead to early detection of conditions and diseases.  If eye health is monitored throughout life there is an increased likelihood that vision loss due to macular degeneration, amblyopia (lazy-eye) and glaucoma can be prevented.

Parents should be leading by example and monitoring their own and their children’s eye health on a regular basis.  Parents should be confident that their children’s eye health is the best it can be.

How to ensure you and your family have good vision for life.

  • Wear sunglasses when outdoors

  • Use appropriate eye protection when required in the workplace, school and home

  • Know your eyes; understand potential warning signs and look for any changes in your vision

  • Have your eyes examined regularly by your optometrist

  • Eat for your eyes; include plenty of vitamin C, vitamin E, zinc and beta-carotene, many of which are found in dark green leafy vegetables or fish sources

Glaucoma The facts

Glaucoma-the-facts

Glaucoma is an eye disease where the optic nerve at the back of the eye is slowly and permanently damaged The greatest risk factor is raised pressure inside the eye, although, in some cases people may have normal eye pressure and still have glaucoma.  Vision loss from glaucoma tends to be slow and start from the peripheral field of vision.  Like hearing loss, it may not be noticed until it is in late stages Damage caused by glaucoma is irreversible but the condition is treatable.  Ideally glaucoma is diagnosed in its early stages where the most common way to treat glaucoma is by using medications to lower the eye pressure.

Glaucoma remains the leading cause of avoidable blindness worldwide.  Current estimates suggest that over 300,000 Australians are affected and that 50% of those living with glaucoma are undiagnosed. 

While nine out of ten Australians say that sight is their most valued sense, over eight million Australians do not have regular eye tests. 

Simple Facts about Glaucoma: 

  • Glaucoma is a progressive eye disease and is the leading cause of irreversible blindness in Australia 
  • It is often referred to as the ‘silent thief of sight’ as glaucoma develops slowly and typically without any symptoms.  The risk is that glaucoma is often undetected until the disease reaches an advanced stage.  Left untreated, glaucoma can cause severe vision loss and lead to blindness. 
  • Vision loss can’t be restored, so early diagnosis and treatment it critically important to delay or halt the progression of the disease.  
  • It is estimated that there are 300,000 Australians living with glaucoma, but over 50% are unaware they have it, thinking they have healthy eyes. 
  • Glaucoma is hereditary disease.  Relatives of a family member with glaucoma are up to ten times more likely to develop glaucoma themselves. 
  • The risk increases to approximately one in four for first degree relatives of a glaucoma sufferer 

Anyone may develop glaucoma, however, 

some people have a higher risk.  

Risk factors include people who: 

Risk Factors:

  • Have a family history of glaucoma 
  • Have high eye pressure 
  • Are aged over 50, the risk increases with every decade of life over age 40 
  • Are of African or Asian descent 
  • Have diabetes 
  • Have myopia (nearsighted) 
  • Have been on a prolonged course of steroid medications 
  • Experience migraines 
  • Have had an eye operation or eye injury 
  • Who have a history or high or low blood pressure 

Abridged: NHMRC Guidelines, 2010 

An eye examination is a completely painless process and on average takes only thirty minutes of your time. 

As part of a routine eye examination a thorough check of the health of the eye is conducted.  This includes examining the optic nerve for features that are suggestive of glaucoma.  The pressure of the eye is also checked and is a painless test.  In cases where glaucoma is suspected more advanced tests are conducted.  These tests included a computerised check for any loss of peripheral vision and a highly accurate ultrasound like test called an OCT (link).  An OCT can scan the optic nerve for signs of nerve damage and can also measure the anatomy of the front of the eye where the ocular fluid pressure is regulated, or drains from the eye. 

Glaucoma Australia recommends all Australians fifty years or older visit an optometrist every two years for a comprehensive eye exam and more frequently if you have any of the risk factors notes above.  It is also recommended to alert first-degree relatives of glaucoma patients to have regular eye checks. 

Behavioural Optometry

behavioural-optometry

What is Behavioural Optometry?

When a child’s vision isn’t working well, no matter how hard the child, parent and teacher try this can interfere with children achieving their best. 

Behavioural optometry goes beyond an eye test, it considers information which each eye is taking in and processing, as visual processing is the key to our understanding of text, symbols and numbers.

Vision assessments performed during a Behavioural Optometry session will also help identify and investigate any poor eye motor control such as:

  • Lazy eyes
  • Developmental delays
  • Acquired brain injuries
  • Concussion
  • Delays in learning to read or,
  • Problems learning to read. 
behavioural-optometry

How do I know if my child needs to see a behavioural Optometrist?

Even if your child can see the board clearly in class or has 20/20 vision, they may still have a vision problem. Sometimes, children may not develop the necessary visual processing skills to understand letters, numbers or words, they may also struggle with the hand-eye skills needed for writing causing problems with literacy or numeracy. 

A trained Behavioural Optometrist will assess these conditions and provide guidance and the visual help required.

Many children with reading difficulties also have a vision problem

For Eyes Optometry have helped many children with vision problems, often these vision problems relate to focusing, eye teaming and stamina.

Children with these vision problems may find it difficult to concentrate when reading or writing. Or they may not be as accurate or fluent in their reading, especially when reading for longer periods. 

Quick and painless testing

At For Eyes Fremantle, we use state-of-the art equipment to conduct a thorough ocular examination. The child centred examination is interactive, fun and painless, and takes about 45 minutes to complete.

Adrian Rossiter, is a trained Behavioural Optometrist at For Eyes in Fremantle, we recommend if you have any concerns regarding your childrens eye health to get in touch today.