Course: Visual Assessment of Children: The Orthoptist Role
Presented on Wednesday 9 February 2005
Case study 1
Gillian Coyle, Senior Orthoptist
Functional Vision Assessment
Ms Elspeth Lymburn - Orthoptist
Dr Margot Campbell - Staff Grade Community Paediatrician
Ms Eunice Ridley - Specialist Teacher for Children with Visual Impairment
Bartleby attended the Metraton School Clinic for a Functional Vision Assessment with his mother on dd/mm/yy. Bartleby is known to have a degree of visual impairment and the purpose of the assessment was to describe his visual difficulties and visual ability. The information is for his parents and his teachers and to consider appropriate strategies for him.
Bartleby has cerebral palsy in the form of a mild asymmetrical diplegia. He also has learning difficulties and partial epilepsy. Bartleby has had a MRI brain scan in the past, which showed ventricular dilatation and periventricular leukomalacia.
Bartleby attends the Ophthalmology Clinic. He is known to have cerebral visual impairment and bilateral optic nerve atrophy. He also is long sighted and has a divergent squint and wears glasses to help correct this.
Parents Impression of Vision
Bartleby does not feel confident mobilising in new surroundings. He trips over objects in front of him. He has particular difficulty judging changes in surfaces. He has problems distinguishing a line from a step and has difficulty on unfamiliar stairs. Bartleby can misjudge doorways in new surroundings and may bump into things on either side. Bartleby manages best in familiar surroundings. He has a good visual memory and remembers where things are. Bartleby has no problem recognising people before they speak. He enjoys looking at photographs and he recognises himself and others in the pictures. He has no difficulty recognising shapes and objects. He knows his colours.
Bartleby has difficulty following fast moving objects. He enjoys the TV, but prefers animation such as Postman Pat as opposed to fast moving cartoons. Bartleby is able to catch a ball thrown directly to him. He has difficulty predicting where it is going to land.
This is a measure of the ability to discriminate detail both close up and at a distance. Bartleby was tested wearing his glasses.
The test used was the McClure reading test at 20cms. Bartleby was able to identify single letters in the N12 text size, eg; S.
Two different tests were used. The Logmar Crowded test, presenting a line of letters to identify, and an uncrowded test presenting single letters to be identified. Bartleby's visual acuity with both eyes open on the uncrowded test measured 6/30 and on the crowded test was <6/38.
This is the area over which one can see without moving the head or the eyes. We found Bartleby to have complete loss of the lower half of his visual field. We found the upper field to be slightly constricted.
This is a measure of the ability to see shades of grey against a white background. The test used was Hiding Heidi. At 3m contrast sensitivity was 5%, which is about half normal. At 1m this increased to 2.5%, which is only slightly reduced.
Recognition of Facial Expressions
Bartleby had no difficulty recognising facial expressions at a distance of 3m.
The test used was the PV16 Panel Colour Vision test. Bartleby has normal colour vision.
A right/alternating divergent squint was noted. Smooth eye movements were grossly full. Saccades or rapid eye movements were satisfactory.
- Bartleby has reduced visual acuity. There is also a "crowding effect" on his vision.
This means that it is easier to identify single letters than to read a line of letters. Similarly
it is easier to identify objects against a plain background than in a clutter. Although Bartleby
was able to read single letters in N12, he may find the larger print easier when learning to read.
Mrs Ridley will advise with regard to this. Distance acuity was approximately 6/30. In practical
terms this means that Bartleby needs to be 1m away to see the detail a person with normal
vision sees at 5m. In a busy visual scene however, he is less able to see detail.
- Bartleby has a significant visual field defect. He has complete loss of the lower half
of the field and some constriction of the upper field. This explains why Bartleby trips over
objects in front of him and contributes to his difficulty on unfamiliar stairs and uneven ground.
When Bartleby is looking ahead, he cannot see his feet or the ground in front of him. When he
lowers his head enough to see his feet, he cannot see ahead. Bartleby may need help to learn
to stop, look at his feet, then look up and move forward. As Bartleby gets taller the area in front
he cannot see will increase.
People with lower field defects often enjoy horse ridin. In this situation the horse takes over navigation of objects directly in front.
The visual field defect also has implications for the presentation of Bartleby's schoolwork, etc; the use of a sloping board, height of workstation. Mrs Ridley will give the appropriate advice.
- Bartleby has particular difficulty on new stairs and uneven ground. People with cerebral palsy often
have difficulty with depth perception. The presence of a squint can also add to this difficulty.
There are a number of factors influencing Bartleby's vision for mobility. It may be helpful for Bartleby to have a mobility assessment and I will consider this further with Mrs Ridley.
- Bartleby has slightly reduced contrast sensitivity, which increases in the distance. Low contrast educational material, eg; poor photocopies, should be avoided.
- From the history, Bartleby has difficulty following fast moving objects and dislikes watching cartoons. He does not appear to have significant difficulties with eye movements. However, people with cerebral palsy often require more time to process and to react to visual informtion, and this ppears to be the case with Bartleby. In addition, people with cerebral palsy often find their vision tires easily and visual abilities may vary during the course of the day. Bartleby's carers and teachers should be aware of this.
Dr Margot Cambell
Education & Children's Services
Report by Teacher for Visually Impaired Children on: Bartleby
See Functional Vision Assessment of dd/mm/yy.
- During Bartleby's visit to the Functional Vision Clinic he displayed
quite remarkable powers of concentration and active involvement in the tasks set.
During this clinic there were, naturally, no visual or aural distractions and no other
children to draw his interest off task. He never "switched off!"
I would conclude from this and other observations, that Bartleby's best concentration for learning and retaining new skills and concepts will occur when he is in a visually and aurally quiet environment, eg; when in a 1-1 situation with his support for learning teacher or assistant outwith the classroom.
Within the classroom he learns the social and emotional skills of conversation, sharing, turn taking, games and how to cope with the visual and aural confusion of the everyday world.
- Bartleby cannot see the floor in front of him unless he deliberately moves his head down.
- When negotiating the steps to the playground he does not require to put both feet on any
step but can ascend and descend normally. He does not always need to use the banister.
He is very familiar with these steps, hence the confidence.
- When concentrating fully Bartleby can see and discuss very small details from illustrations.
He can also search for and read items at 1 m distance, eg; the date on the board. However,
he should not be "expected" to do either of the above.
- Bartleby will benefit from having print no smaller than point 16 - see sample.
- Because of his loss of the lower field of vision Bartleby would benefit from using the
magnetic sloping board at a slope of 45° to start with, for both reading and writing.
This mayor may not need raised. Raising the page upwards will mean that Bartleby sees
more of it, as it will be in his upper field of vision. This board will also remove some
- When practising handwriting it would be of benefit to Bartleby if he saw only one short sentence at a time.
- Bartleby benefits from having the minimum amount of information on a page.
The information should be well-spaced, eg; double line spacing and double-spacing between words.
Illustrations should be separate from text. Bartleby's visual acuity is poorer when the page is crowded -
see Functional Vision Assessment.
- He should not be positioned to look down on a PC, television, book etc.
- Bartleby needs to be reminded to look down frequently when walking, then to look up and move forward.
- I will undertake some mobility training with Bartleby once I have managed to acquire
a modified cane (hoople). This should make Bartleby more aware of what is present at his feet.
- I note with interest the recommendation regarding horse riding in the Functional Vision Report.
- Throughout the day, at home and school, Bartleby will continue to benefit from being encouraged to achieve independent self-help skills, eg; getting his snack, eating meals, dressing himself and improving on his ability to complete a work task independently.
Bartleby continues to make progress in both his learning and his social skills.
Eunice Ridley Teacher for Visually Impaired Children