Glossary

The information provided here is necessarily brief. Users who wish to know more about any of the subjects covered are advised to search the internet. However, it is important to bear in mind that information obtained from websites can be confusing; this is illustrated by the different ways the term "Laurence-Moon-Biedl-Bardet syndrome" is viewed at the time this Glossary was compiled (16th December 2014). Of course, information obtained from printed material (journal articles and books) can also be confusing.

Users should also bear in mind that not all websites can be trusted. Again, this reflects the situation with printed material: not all articles published in newspapers can be trusted.

It is advisable to be critical when reading and considering any information, including that obtained from the internet.

Aniridia

A congenital condition that involves the under-development of the iris. The iris is the part of the eye usually coloured blue, grey, brown, hazel or green. In severe forms of autism, the iris appears to be almost completely absent. autism usually occurs with other abnormalities of the eye.

Autism

autism is also known as autistic spectrum disorder (ASD) or autistic spectrum condition (ASC). It is a continuum condition typified by the "triad of impairments", that is impairments in:

• social relationships
• social communication
• social imagination.

The triad has been expanded to include difficulties in sensory domains. People with autism tend to be literal and concrete in their thinking, have difficulty empathising with others, have special interests or obsessions and require structure / routine in their lives. Increased mental health difficulties are more common in autistic than neuro-typical people.

There is much variability on the spectrum; people with Asperger syndrome have fewer problems using spoken language than most autistic people. Many are of average, or above average, intelligence. Most do not have the accompanying learning disabilities associated with autism, but they may have specific learning difficulties. These may include dyslexia, dyspraxia, attention deficit hyperactivity disorder (ADHD) and epilepsy.

Additional sources of information on autism are provided in the Resources section.

Braille

A tactile code for reading and writing used by people who are unable to read print because of severe visual impairment. It is based on different combinations of the six raised dots that form a braille cell. As well as English braille, there are different codes for mathematics, music and most other languages.

Alphabetic, or uncontracted braille, is the simplest form of braille. A single braille cell is used to represent each letter of the alphabet. There are separate signs for punctuation. Alphabetic braille was previously known as grade 1 braille.

Contracted braille is a more advanced form of the braille code than alphabetic braille. Word signs and contractions are used. There are rules about how and where these can be used within text. Contracted braille was previously known as grade 2 braille.

Moon is an alternative tactile reading system; some people find it easier to use than braille.

Additional sources of information on braille are provided in the Resources section.

Cataracts

An opacity (cloudiness) of the lens of the eye. The lens is convex and is formed of a clear, transparent substance that allows light to pass through unimpeded. Opacity of the lens obstructs the passage of light resulting in impaired vision.

CCTV: Close Circuit Television

An optical aid that enlarges print or other images onto a TV screen in front of the user. It enables the user to read print or to see images that would otherwise be too small. The user can focus on a single word or picture if so desired. This has the effect of de-cluttering the source material.

Central vision

The middle part of the field of vision. This is the area of vision where the finest discriminations can be made. We use our central vision for reading.

Cognitive behaviour therapy

Cognitive behavioural therapy (CBT) is a talking therapy that can help people to manage their problems by changing the way they think and behave. It is most commonly used to treat anxiety and depression, but can be useful for other mental and physical health problems.

CBT cannot remove a person"s problems, but it can help the individual to deal with them in a more positive way. It is based on the concept that a person"s thoughts, feelings, physical sensations and actions are interconnected, and that negative thoughts and feelings can trap the person in a vicious cycle.

CBT aims to help people to crack this cycle by breaking down overwhelming problems into smaller parts and showing them how to change these negative patterns to improve the way they feel.

Unlike some other talking treatments, CBT deals with current problems, rather than focusing on issues from the past.

Complex Learning Difficulties and Disabilities (CLDD)

A new category of learning difficulties has recently been formerly recognised in England. This is a result of the Complex Learning difficulties and Disabilities Project. (See http://complexld.ssatrust.org.uk/. Site accessed 16th December 2014.)

The definition of Complex Learning Difficulties and Disabilities is:

"Children and young people with Complex Learning Difficulties and Disabilities have conditions that co-exist. These conditions overlap and interlock creating a complex profile. The co-occurring and compounding nature of complex learning difficulties requires a personalised learning pathway that recognises children and young people"s unique and changing learning patterns. Children and young people with CLDD present with a range of issues and combination of layered needs – e.g. mental health, relationships, behavioural, physical, medical, sensory, communication and cognitive. They need informed specific support and strategies which may include transdisciplinary input to engage effectively in the learning process and to participate actively in classroom activities and the wider community. Their attainments may be inconsistent, presenting an atypical or uneven profile. In the school setting, learners may be working at any educational level, including the National Curriculum and P scales. This definition could also be applicable to learners in Early Years and post-school settings."

There are other categories of learning difficulties; see the separate entries for

• Moderate learning difficulties
• Profound and multiple Learning difficulties
• Severe learning difficulties

Cornea

The transparent, smoothly curved front surface of the eye. The Cornea bends rays of light as they enter the eye so that they come to a focus on the retina.

Cortical dysplasia

This brain disorder is caused before birth. As the brain naturally develops in utero, neurons (which grow in the innermost part of the brain) spread or migrate outward to the cerebral cortex. Cortical dysplasia results when these neurons fail to spread out and position correctly. This leads to various neurological symptoms including epilepsy.

Cortical visual impairment (CVI)

A reduction or disturbance of vision as a result of malfunction of the parts of the brain concerned with vision and / or the visual pathways. The term 'cortical visual impairment' is currently being replaced by 'cerebral visual impairment'. The commonly used abbreviation – 'CVI' – applies to both terms.

Additional sources of information on cortical / cerebral visual impairment are provided in the Resources section.

Crisis

Many young people with autism have difficulty with anxiety. In addition, many become stressed in situations that would not stress a typically developing individual. Stress and anxiety levels sometimes escalate so much that crisis is reached. This is the point at which the young person"s stress or anxiety becomes overwhelming.

Autistic young people can also become overloaded with sensory stimulation. It is not always possible to determine whether a young person is in crisis because of stress or anxiety, or whether he / she is overloaded with sensory stimulation.

Echo location

Use of reflected sound that helps to identify the position of items in the environment. Used in conjunction with other aids to mobility, echo location can help a person with severe visual impairment to move around without bumping into items. 'Flash-sonar' is an alternative phrase that is used to describe echo location.

Field of vision

The area that can be seen by an eye that is being held still at any given moment.

Functional behaviour analysis

When planning how to reduce behaviours which are regarded as challenging or inappropriate, a common first stage is to conduct a functional behaviour analysis. Its purpose is to gain essential information about the behaviour:

• the times when it occurs
• how often it occurs
• where it occurs
• the people who are present when it occurs
• the nature of the environment when it occurs
• what happens after it occurs.

In essence, the purpose of a functional behaviour analysis is to establish why the behaviour occurs – i.e. the functions of the behaviour. This information is then used to develop a positive behaviour plan.

Functional vision

The way in which an individual uses their sight in everyday situations.

Impulsivity

Many people with autism have difficulty regulating their behaviour. They may have problems focusing and concentrating for more than a short period of time and need to be active. Impulsivity causes the child to act suddenly, without thinking through the consequences.

Landmarks

Landmarks are used to support mobility. They are permanent features that occur at key points on a given route. They are used by a young person with visual impairment to confirm location and to orientate towards the next destination. Landmarks can be items that occur naturally in an environment, or they may be placed permanently in a location for the purpose of being a landmark. They may be of a visual, tactile or auditory nature. Olfactory landmarks are not generally used as they are of a non-permanent nature. Landmarks are generally specific for a given young person and are often identified by a mobility teacher. If necessary, they can be chosen specifically to reflect a young person's interest, level of vision, preferred sensory channel or motivation.

Landmarks can be incorporated into trails.

Laurence Moon Bartel Biedl Syndrome (LMBBS)

There is confusion over this syndrome. According to one website, the term Laurence-Moon-Biedl-Bardet syndrome is "no longer considered valid". (See http://www.patient.co.uk/doctor/Laurence-Moon-Syndrome.htm. Site accessed 16th December 2014.)

However, the term continues to be used by the Laurence-Moon-Bardet-Biedl Society. (See http://www.lmbbs.org.uk/. Site accessed 16th December 2014.)

The society provides an information booklet "Introducing LMBBS" from which the following is taken. The main features of Laurence-Moon-Biedl-Bardet syndrome (LMBBS) are:

• visual impairment, caused by rod-cone dystrophy, a progressive eye condition which is often diagnosed as retinitis pigmentosa; it first shows itself as impaired night-vision and can lead to tunnel vision, and ultimately blindness
• obesity
• extra fingers and / or toes (polydactyly) and / or partially fused digits (syndactyly)
• underdeveloped genitals in males (hypogenitalism)
• developmental delay, speech and co-ordination problems, and often, learning difficulties
• other health problems, most frequently kidney (renal) abnormalities.

Not all of the above features are present in every young person with LMBBS, and each feature varies in severity and character among those affected.

Learning difficulties

See separate entries for

• Complex Learning Difficulties and Disabilities
• Moderate learning difficulties
• Profound and multiple learning difficulties
• Severe learning difficulties

Leber's amaurosis

An inherited disorder of the retina affecting both peripheral and central vision that is present from birth.

Light perception

The ability to see the difference between light and dark. People with severe visual impairment may have light perception.

Long cane

A mobility aid for people severe visual impairment. It comprises a light weight metal "stick" coloured white with a specially designed tip. The user sweeps it from side to side in front of them whilst walking. This helps the user to detect changes of level, environmental features, hazards and surface textures. The long cane should not be confused with a symbol cane.

Mainstream school

A school in which most pupils do not have special educational needs.

However, most mainstream schools have some learners with special needs who require access to the curriculum to be modified in order to meet their needs.

Mobility officer / teacher / habilitation officer

An individual who has received specialist training to teach mobility and daily living skills to young people with visual impairment. Similar practitioners working with adults may be called rehabilitation officers.

Moderate learning difficulties (MLD)

Young people with moderate learning difficulties have attainments significantly below expected levels in most areas of the curriculum, despite appropriate interventions. Their needs will not be met by normal differentiation and adaptations. Additional educational provision has to be made to help them to access the curriculum. Young people with moderate learning difficulties have much greater difficulty than their peers in acquiring basic literacy and numeracy skills and in understanding concepts. They may also have associated speech and language delay, low self-esteem, low levels of concentration and under-developed social skills.

There are other categories of learning difficulties; see the separate entries for:

• Complex Learning Difficulties and Disabilities
• Profound and multiple learning difficulties
• Severe learning difficulties

Moon

A system of tactile reading that uses embossed symbols, partially based on capital letters of the Roman alphabet. The symbols are made up of raised curves, angles, and lines. They are easier to distinguish than braille dots. There is a different Moon symbol for each letter of the alphabet. The main disadvantage of Moon is that there is no simple mechanical system for writing it.

Additional sources of information on Moon are provided in the Resources section.

N print size

The designation of print size by the letter 'N' followed by a number, e.g. N9, N18, N24, N36 etc. The larger the number, the larger the print. The standard size for print used in everyday situations is N12, although RNIB recommends N14 in its Clear Print Guidelines.

Nystagmus

Involuntary movements of the eyes. Movements can be side to side, up and down or rotational. Nystagmus is sometimes known as "wobbly eye". The effect on vision of Nystagmus is very variable. It usually occurs in conjunction with another eye condition or a neurological impairment. Occasionally it occurs in isolation with no known cause.

Oculocutaneous albinism

An inherited condition resulting in a reduction of colouration (pigmentation) of the skin and eyes. The structure of the eyes is also affected.

Optic nerve hypoplasia

Congenital under-development of the optic nerves which carry the visual signals from the eyes to the brain.

Overloaded

Many young people with autism have difficulties coping with sensory stimulation. This is particularly likely for those who are single channelled. If a young person is exposed to too much sensory stimulation, he / she becomes overloaded: the sensory stimulation has become overwhelming, and the young person reaches crisis.

Autistic young people can also become overwhelmed and reach crisis as a result of stress or anxiety. It is not always possible to determine whether an individual is in crisis because of stress or anxiety, or whether he / she is overloaded with sensory stimulation.

Peripheral vision

Vision that falls outside the central part of gaze. It involves the sides and the upper and lower areas of vision. Peripheral vision is less acute than central vision but it is very responsive to movement. Movements that are detected by peripheral vision will usually result in gaze being focused on the source of movement.

Profound and multiple learning difficulties (PMLD)

Young people with profound and multiple learning difficulties have complex learning needs. In addition to very severe learning difficulties, young people with PMLD have other significant difficulties, such as physical disabilities, sensory impairment or a severe medical condition. Individuals with PMLD require a high level of adult support, both for their learning needs and also for their personal care. They are likely to need sensory stimulation and a curriculum broken down into very small steps. Most young people with PMLD communicate using pre-language means such as facial expression, body language, vocalisation, gesture and eye pointing.

There are other categories of learning difficulties; see the separate entries for:

• Complex Learning Difficulties and Disabilities
• Moderate learning difficulties
• Severe learning difficulties

Proprioception

Proprioception is the sensory system that is stimulated by the information gained from our joints, tendons and muscles. It informs us about the position of our body parts in relation to each other. A poorly developed proprioceptive sense can lead to many difficulties, including:

• poor stability
• poor motor skills (gross and fine)
• difficulty imitating movements
• poor coordination
• a need to stimulate the proprioceptive (and vestibular) sense by increased movement.

Registration as severely sight impaired or blind

Registration is a formal process undertaken by the social services department of a local authority in the UK. It means that a person satisfies the legal definition of being severely sight impaired or blind. This is that, whilst wearing any prescribed spectacles or lenses, the person has:

• Visual acuity of less than 3 / 60 with a full field of vision
• visual acuity between 3 / 60 and 6 / 60 with a severe reduction of field of vision, such as tunnel vision
• visual acuity of 6 / 60 or above but with a very reduced field of vision, especially if a lot of sight is missing in the lower part of the field.

See also the entry on visual impairment.

Residual vision

Any useful sight of a person with severe visual impairment. The person may have a very limited amount of vision, but is often able to make good use of this in everyday situations. For example, a person who has light perception only may use this to orientate towards a window, so helping to understand where they are in a room.

Resource base

Special provision sited in a mainstream school for young people with a designated special need (e.g. visual impairment or autism). The Resource base usually forms a centre from which specialist staff work.

Retina

The retina is at the back of the eye. It contains light-sensitive cells and is responsible for converting light into neural energy so that messages can be sent to the brain.

Self stimulatory activities

Activities such as rocking, hand flapping, head weaving, tapping and twirling which provide sensory stimulation.

Sensitivity to light

An intolerance of light, especially glare or bright light. It results in a person being in discomfort and having reduced vision when affected by glare or bright light. It is also known as 'photophobia'. Some young people with sensitivity to light are provided with tinted spectacles.

Sensory integration

At its simplest, the term sensory integration means "The organisation of sensory input for use". The "use" may be

• a perception of the body (how the brain interprets or gives meaning to sensory information)
• an adaptive response
• a learning process
• the development of some neural function.

Through sensory integration, the many parts of the nervous system work together so that a person can interact with the environment effectively and can participate successfully in as wide a variety of activities as they need to in order to live a full and satisfying a life.

Additional sources of information on sensory integration are provided in the Resources section.

Septo-optic dysplasia

A congenital condition which results in the under development of the optic nerves, which carry the visual signals from the eyes to the brain, deficiency of the function of the pituitary gland and some brain abnormality.

Severe learning difficulties (SLD)

Young people with severe learning difficulties have significant intellectual or cognitive impairments. This has a major effect on their ability to participate in the school curriculum without support. They may also have difficulties in mobility and co-ordination, communication and perception and the acquisition of self-help skills. Young people with SLD need support in all areas of the curriculum. They may also require teaching of self-help, independence and social skills. Some individuals use sign and / or symbols.

There are other categories of learning difficulties; see the separate entries for:

• Complex Learning Difficulties and Disabilities
• Moderate learning difficulties
• Profound and multiple learning difficulties

Sighted guide

A person with good vision who provides assistance to someone who has severe visual impairment. The correct technique of sighted guiding involves the visually impaired person holding the arm of the sighted person just above the elbow.

Single channelled

Many young people with autism have difficulties attending simultaneously to information from more than one channel (sense). They can become easily distracted or overloaded when multi-channel information is received and therefore tend to function best when information is presented via one channel (sense) at a time.

For example, when a single-channelled young person is listening, he / she cannot also look; when looking, he / she cannot also listen to and understand what someone else is saying. This helps to explain why young people with autism avoid eye contact when communicating with another person.

Special School

A school for young people with special educational needs, such as learning difficulties, visual impairment or autism.

Symbol cane

Much shorter than a long cane, a symbol cane is a short white cane used by people who are partially sighted. Held statically in front of the user, it acts as a symbol to others that the user has poor sight.

Tactile defensive

A term that is often applied to a young person who has an aversion to using their hands to explore objects by touch, especially when required to do so by an adult. An individual who is tactile defensive will resist being encouraged to feel items and will withdraw his / her hands from the engagement. The young person will usually show displeasure and discomfort when required to touch items.

Tinted spectacles

Spectacles that have coloured lenses. Usually, the purpose of the colouration of the lenses is to reduce the amount of light or glare that enters the eye. Too much light or glare can have an adverse effect on vision. They are provided for some young people with sensitivity to light.

Tinted lenses are also used to help some young people who have a specific learning difficulty connected with reading.

Trails

A trail is used to support the mobility of a visually impaired young person on a route between two points. It helps the individual to memorise the route and to predict what he / she will encounter next. The trail can have a number of special features of a visual, auditory or tactile nature. These features are used as landmarks.

Trailing involves using a hand to feel the way along a wall or other environmental feature such as a dado rail.

Transition

Practitioners who support sighted young people with autism use the term "transition" in a way which may not be familiar to those who work with visually impaired young people. In the context of sighted young people with autism, "transition" has one basic meaning: "change". However, it has several uses. Perhaps the most frequent use refers to a change of location, i.e. to moving ("transitioning") around the physical environment.

However, "transition" can be used to refer to a change in any aspect of daily life, such as a transition from one activity to another or a transition from one member of staff to another.

Because many young people with visual impairment and autism do not cope well with change, transitions can be extremely difficult for them. For further information see supporting the young person to cope with transitions and transitions and mobility.

Practitioners who work with visually impaired young people are likely to be familiar with another use of "transition": this refers to major changes such as that at the age of 11 from primary school to secondary school and, later from school to college. The latter may also involve a transition from living at home to living away from home. Transitions of this kind can be particularly difficult for young people with visual impairment and autism, who should receive considerable support at such times.

Tunnel vision

Someone with tunnel vision has a small area of central vision, but significantly reduced peripheral vision. As vision is clearest in the centre of the field of vision, a person with tunnel vision may be able to see very clearly over this very small area.

Vestibular sense

The vestibular system controls our sense of balance. It is linked with:

• posture and mobility
• planning and carrying out a sequence of movements
• perceptual awareness
• use of vision
• auditory processing
• breathing.

Visual acuity

A measure of the finest detail that can be seen under optimum conditions. Distance visual acuity is often expressed as a fraction-like figure e.g. 6/60, 6/36. These mean that a person with impaired vision can only read at 6 metres distance what a person with normal sight would be able to read at 60 (6/60) or 36 (6/36) metres. Normal visual acuity is shown as 6/6. Increasingly, visual acuity is expressed in logarithmic terms with 6/6 having a value of 0.00 and 6/60 having a value of 1.00.

Visual impairment

A permanent reduction or absence of vision that cannot be corrected with spectacles or contact lenses.

See also Registration as severely sight impaired / blind.

Additional sources of information on visual impairment are provided in the Resources section.