Continuing Education

Author: Dr Robert Cubbidge and Amy Whiskens

View PDF

Dr Robert Cubbidge and Amy Whiskens describe autism and related conditions and examine perceptual and visual impacts. C4765, one standard CET point

This module has now closed - you cannot earn any CET points.

THIS ARTICLE IS BEST VIEWED IN A PDF FORMAT

Autistic spectrum disorder (ASD) is a term used to describe a lifelong developmental disorder characterised by impairments in social interaction, communication, and imagination. The degree to which an individual is affected varies, hence the term spectrum disorder. Some individuals with ASD have severe learning disabilities and may never speak, while at the opposite extreme around 25 per cent of people with an ASD have normal intelligence and a small percentage have above average intelligence.2 Many of these individuals may have a diagnosis of Asperger's syndrome.

Asperger's syndrome was first described by Hans Asperger in 1944. Individuals with the syndrome have normal intelligence, as measured by intelligence quotient (IQ), but exhibit autistic-like behaviour. They also tend to prefer an unchanging environment and show marked deficiencies in social skills. They will often have obsessive routines and become engrossed in a particular subject of interest. They experience difficulty with social interaction, finding interpretation of body language challenging. They can be considered to be oversensitive to sensory stimuli such as smell, taste and certain visual environments. They may demonstrate odd or unusual behaviour, but it must be remembered this is not intentional rudeness or bad behaviour.

DIAGNOSIS

The American Psychiatric Association's diagnostic and statistical manual of mental disorders describes individuals with an ASD as experiencing three main areas of difficulty, known as the triad of impairments.

1 Social interaction: Individuals with an ASD experience difficulty with social relationships, appearing aloof and indifferent to other people or passively accepting social contact. While they may show some signs of pleasure in contact, they rarely make spontaneous approaches to others

2 Social communication: Individuals with an ASD often struggle with verbal and non-verbal communication. For example, they may not understand the meaning of gestures, facial expressions or tone of voice. The language they use may be very literal, and they may make idiosyncratic or odd choices in words and phrases. Their speech content is often limited

3 Imagination: Individuals with an ASD may not be able to develop creative play or imagination skills. For example, children with an ASD do not play 'let's pretend' in the way that other children do. They have a limited range of imaginative activities, possibly copied, which are then pursued rigidly and repetitively. They tend to focus on minor or trivial things around them, for example an earring, rather than the person wearing it.

Asperger's syndrome describes individuals at the high cognitive function region of the autistic spectrum. Some researchers feel it is a separate condition, and that people with Asperger's may not wish to be referred to as having an ASD. Individuals with Asperger's generally have fewer problems with language, often speaking fluently however, their words can sound formal or stilted. They tend to exhibit repetitive behaviour and a resistance to changes in routine. They may become obsessed with particular objects or behaviours, focusing on them to the exclusion of all else around them. They may also be hyper- or hypo-sensitive to sound, touch, pain, lights, etc.

EPIDEMIOLOGY

The prevalence of ASD is estimated at 0.6 per cent of the population,4 although a recent study in The Lancet suggested it may be as high as 1 in 100 children. It is thought to affect more than 500,000 people in the UK5 and is found in roughly equal numbers across cultures and social classes. There is, however, a significant difference between sexes, with approximately three times as many males affected as females.6 Asperger's syndrome affects almost five times more males.7 The age of onset is unclear but is thought to be between birth and three months. Diagnosis, however, does not usually occur until later and is partly dependent on the nature of the ASD. Diagnosis for general autism is usually made at around age five, and age 11 for Asperger's. Public perception is that autism has become increasingly common during the last decade. There has been much debate as to the reasons for this, but the increase is probably due to a combination of factors including better diagnostic procedures, increased public awareness and a possible increase in causative factors.

AETIOLOGY

The causal origins of ASDs are currently unknown. Research has suggested several factors which may be involved.

Genetics

Twin and family studies have shown that ASDs appear to be highly hereditary.8 It is thought that genetic causes of ASD are complex and rarely due to a single gene, but are instead due to a complex interaction between genes. The current thinking is that a genetic predisposition may interact with organic brain damage to produce an ASD.

Pregnancy and birth complications

Difficulties with birth and pregnancy may be associated with autism.9 These may include such risk factors as a 'rhesus incompatibility' between mother and child blood groups, taking medication during pregnancy, meconium (the first stools of the infant) present in the amniotic fluid during labour, bleeding between the fourth and eight months of pregnancy and mother's age above 35 years at the time of the child's birth.

Diet and metabolism

It has been suggested that an inability to metabolise specific foodstuffs adequately could lead to toxins entering the bloodstream via the gut wall and potentially crossing the blood brain barrier.20 Anecdotal evidence has suggested that some individuals with an ASD may find improvements by following a gluten free (wheat-free) or casein-free (dairy-free) diet.

Brain structure and/or function

Overall brain size in ASD has been found to be larger by 2-10 per cent than neurotypical individuals. In ASD, at birth the brain is likely to be slightly smaller. It then undergoes a period of rapid and abnormal growth up to one year of age, when the brain size plateaus. By adulthood, the brain is within the normal size range or larger.12 ASD is also associated with abnormal cortical organisation and connectivity.

Environmental factors

Pre-natal exposure to thalidomide, valproic acid used to treat epileptic seizures, cocaine and alcohol have all been implicated as causal factors in the development of ASDs. Mercuric compounds such as methyl mercury have also been suggested as a potential causal factor. This has led to concerns about the use of thimerosal, which is 49 per cent ethyl mercury, as a preservative in vaccines. Studies so far have proved inconclusive. It is interesting to remember that thimerosal was once a commonly encountered preservative in soft contact lens solutions, although there is no documented link between its use and ASD.

MMR vaccination

The most publicised and controversial suggested cause of autism is the MMR (measles, mumps, rubella) vaccination. A possible link was identified by Dr Andrew Wakefield, who theorised there was a link between MMR, inflammatory bowel disease and autism.13 As a result, rates of MMR vaccination in England have dropped to as low as 60 per cent in some areas, and this is reflected in increased cases of potentially fatal measles. Since the Wakefield study, several large scale investigations have reported there is no causal link between the vaccine and autism.14,15 The overwhelming majority of scientific opinion believes the vaccine is safe. The Medical Research Council concluded that while there was not sufficient evidence to show a causal link, more research was needed in this area.4

OCULAR AND VISUAL CHARACTERISTICS

Autistic children have unequal developmental profiles in all their sensory areas. Therefore they may show hypo- or hyper-sensitivity to different stimuli. In fact it may be these atypical responses to sensory stimuli which first lead to suspicions of a problem in young children or babies. There is little literature available about vision in people who have an ASD, especially in adults. Many symptoms which are thought to be linked with ASD have only anecdotal evidence and have not been investigated by detailed studies.

Abnormal ERG

About 48 per cent of individuals with autism may have abnormal ERG responses.1 This may be caused by a low level metabolic disturbance in these individuals, which affects retinal physiology.

Variable Rx and strabismus

Creedon and Scharre16 reported that 41 per cent of individuals with ASD had a significant refractive error (defined as >1D), although no trend was found for any particular type of error. Strabismus was found in 21 per cent of the children, compared with the general population incidence of approximately 3 per cent.

Oculomotor dysfunction

Abnormal viewing behaviour is a characteristic feature of autism a lack of gaze tracking is apparent in autism at 18 months and is one of the earliest detectable symptoms. Differences may be present between both viewing patterns and gaze direction when viewing a scene with social context by an individual with ASD and a normal individual.17 Differences have been found in pursuit movements18 and saccades children with an ASD have been found to make more saccades during presentation of and between stimuli than those without the condition.

Motion perception

Perception of moving stimuli is impaired in ASD. Individuals show raised thresholds for perceiving coherent motion and also postural hypo-reactivity to visual motion - a lack of physical response by an individual to an illusion, which induces a sense of self motion. Table 1 summarises visual characteristics in ASDs.

COLOURED LENS USE

It has been suggested that the use of coloured lenses can improve symptoms in both dyslexia and autism from motor control to eye contact. The anecdotal accounts of improvements range from mild to dramatic, but there have been no placebo controlled trials which confirm these suggested benefits.

EXAMINING A PATIENT WITH ASD

The key word to remember when examining a patient with an ASD is 'individual', due to the wide variation in the spectrum. The National Autistic Society (www.nas.org.uk)5 has made several suggestions for examining patients which can be incorporated into an optometrist's routine.

Appointments

Wherever possible, it is useful to give a patient with an ASD the first or last appointment of the day. Individuals with an ASD often find waiting extremely stressful, so waiting in a busy area may increase stress levels in an already anxious individual. If possible, find a side room the family/patient can wait in, or they may prefer to wait outside in the car, where a member of staff can collect them when the optometrist is ready.

Communicating with patients

◆ Use clear simple language with short sentences

◆ People with an ASD tend to take everything literally. It is important to be precise, and avoid idioms, irony, metaphors and words with double meanings. For example saying 'It's raining cats and dogs out there' could prompt the patient to look outside for cats and dogs

◆ Give direct requests. For example, 'Please stand up.' Asking 'Can you stand up?' may result in the person staying seated or giving the answer 'Yes', as the person may not understand you are asking them to do something

◆ Check they have understood what you have said some people with an ASD may speak clearly but can lack full understanding

◆ Avoid using gestures or facial expressions without verbal instructions

◆ Ask for the information you need. A person with an ASD may not realise what you want to know unless you actually ask them

◆ Don't be surprised if the patient doesn't make eye contact, but this does not mean they are not listening

◆ Allow the patient extra time to process what you have said

◆ Don't assume that a non-verbal patient cannot understand what you are saying.

Other considerations

◆ Examinations can be very stressful to the patient, so it is essential to warn them before touching them. Explain what you are going to do, and why

◆ Enlist the parent/carer's help wherever possible, especially if the patient is non-verbal or uses an alternative communication method or aid

◆ Some people with an ASD are extremely sensitive to light. Even pen lights can trigger seizures in susceptible individuals. Seizures occur in 20-30 per cent of people with an ASD19

◆ Plan an informal trip prior to the actual appointment. It may be useful for the person with ASD to meet you so they will get to know you as well as the room and any equipment

◆ Another option may be to allow a child with an ASD to watch while a sibling is treated so that subsequent appointments will not be such a shock. The advice of the patient's carer will help to inform this approach.

It is important to bear in mind going to see an optometrist can cause sensory overload for people with an ASD. The equipment used, such as the heavy eye glasses and bright lights, can be difficult for them to cope with. This can cause the patient to have a 'meltdown' where they may become distressed. Some might withdraw by putting their fingers in their ears and closing their eyes, while other may 'stim' which can mean flapping hands, flicking fingers and rocking. This kind of behaviour is calming to the individual, so it is advisable not to intervene to stop it unless absolutely essential.

SUMMARY

With rising rates of ASDs we all need to be aware of the characteristics and needs of these individuals. There is little information available on eye care and visual function in such individuals. Research into this area will produce more useful information about this interesting group.

References

1 Creel DEA. Abnormal electroretinograms in autism. Clinical Vision Science, 19894(1):85-88.

2 Volkmar FR, and Pauls D. Autism. Lancet, 2003362(9390):1133-41.

3 American Pyshicatric Association. Diagnostic and Statistical Manual of Mental Disorders DSM-IV-TR Fourth. 4th ed. American Psychiatric Publishing. 2000943.

4 Medical Research Council. MRC review of autism research, epidemiology and causes. 2001.

5 National Autistic Society. www.nas.org.uk 2006.

6 Steffenburg S, and Gillberg C. Autism and autistic-like conditions in Swedish rural and urban areas: A population study. Br J Psychiatry, 1986149:81-7.

7 Rutter M, and Schopler E. Autism and pervasive developmental disorders: Concepts and diagnostic issues. J Autism Dev Disord, 198717(2):159-86.

8 Bailey A et al. Autism as a strongly genetic disorder: Evidence from a British twin study. Psychol Med, 199525(1):63-77.

9 Baron-cohen B. Autism: The facts. Oxford University Press, 1993:122 pages.

10 Stromland K et al. Autism in thalidomide embryopathy: A population study. Dev Med Child Neurol, 199436(4):351-6.

11 Christianson AL, Chesler N, and Kromberg, JG. Fetal valproate syndrome: Clinical and neuro-developmental features in two sibling pairs. Dev Med Child Neurol, 199436(4):361-9.

12 Redcay E.a.C, E. When Is the Brain Enlarged in Autism? A Meta-Analysis of All Brain Size Reports. Biological psychiatry, 200558(1):1-9.

13 Wakefield AJ. MMR vaccination and autism. Lancet, 1999354(9182):949-50.

14 Katsanis J et al. Heritability of different measures of smooth pursuit eye tracking dysfunction: A study of normal twins. Psychophysiology, 200037(6):724-30.

15 Medicines, T.C.o.t.S.o., Working Party on MMR Vaccine 1999.

16 Scharre JE, and Creedon MP. Assessment of visual function in autistic children. Optom Vis Sci, 199269(6):433-9.

17 Klin A et al. The enactive mind, or from actions to cognition: Lessons from autism. Philos Trans R Soc Lond B Biol Sci, 2003358(1430):345-60.

18 Takarae Y et al. Pursuit eye movement deficits in autism. Brain, 2004127(Pt 12):2584-94.

19 Kagan-Kushnir T, et al, Screening electroencephalograms in spectrum disorders: Evidence-based guideline. Journal of Child Neurology, 200520(3):197-206.

20 Jordan R. Autism and autistic-like conditions in mental retardation. J Child Psychol Psyc 40:831.

◆ Dr Robert Cubbidge is a lecturer in the Division of Optometry at Aston University where Amy Whiskens is undertaking a PhD

Providing exclusive eye care news, information and educational needs every week, including a FREE CET programme. Subscribe to Optician Print Edition.