«Training Programme for Public Health Nurses and Doctors in Child Health Screening, Surveillance and Health Promotion Unit 2 Vision Screening January ...»
for Public Health Nurses and Doctors
in Child Health Screening, Surveillance and Health Promotion
The Programme of Action for Children wishes to thank
Mr John McCance, Senior Orthoptist, NWHB
Ms Eileen Buckley, Senior Orthoptist, NWHB
Dr Joanne Kearney, Community Ophthalmic Physician, NWHB
Ms Bronagh McAuley Orthoptist NWHB
Ms Clare Hannigan Senior Orthoptist NWHB
for their work in the development of this Training Module.
This work was supported by Dr Maureen Hillery Community Ophthalmic Physician, SEHB Mr Tony McAleer, Senior Orthoptist, Royal Victoria Eye and Ear Hospital Ms Beatrix Haskins, Senior Orthoptist, SHB Ms Teresa Cawley, Training and Development Officer, NWHB.
Dr Christine McMaster, CAHDO, NWHB Mr Patrick Mc Cance Head Orthoptist Altnagelvin Hospital Derry Special thanks to CARMEL for all her help and patience in typing this document.
Vision Screening Training for Area Medical Officers, Public Health Nurses & School Nurses Contents Introduction ……………………………………………….…… Page 3 Aims and outcomes Mandate and founding documents Definitions ……………………………………………………… Page 5 Development of the eye ……………………………………… Page 7 Ocular anatomy Visual pathways Growth and development of the eye Development of vision ……………………………………….. Page 9 Critical period Barriers to normal vision development Amblyopia Crowding effect Behaviour of the visual impaired child Care of a visually impaired child Development of binocular single vision …………Page 10 Requirements for the development of BSV Binocular reflexes Advantages of BSV Assessing vision ……………………………………………… Page 11 Why test for vision Vision test Visual acuity is affected by How vision is assessed How vision is recorded What if a child cannot see 6/60 Types of vision tests Sonsken – Silver Snellen (illuminated) Logmar Test Standards/Rationale Assessing for a squint ………………………………………..Page 17 Squint / Strabismus Types of squints Pseudosquint Assessment of corneal reflections Colour Blindness …………………………………………… Page 20 Colour Vision Test Referral Criteria for Eye Clinic ………………………….…. Page 22 Criteria Additional information when referring What happens upon referral DNA policy Flow chart Squint and Lazy Eye – Some questions answered ……….. Page 26 Appendices …………………………………………………….. Page 29 Abbreviations used by the Ophthalmic Department References ……………………………………………………… Page 30
The aim of this pack is to provide a resource for Area Medical Officers, Public Health Nurses, School Nurses & other Health Professionals involved in vision screening.
This pack will provide information on visual development, how to assess and record levels of visual acuity, identify the presence of a squint and ocular movement problems.
Why the need for such training?
The Department of Health and Children carried out a review of children’s eye
services and one of the recommendations state that:
Standardised training should be established for Area Medical Officers, School Nurses and Public Health Nurses.
This training is to be provided by the Area Orthoptic/Ophthalmic Service in the North Western Health Board.
AIMS & OUTCOMES FOR AREA MEDICAL OFFICERS, PUBLIC HEALTH
NURSES & SCHOOL NURSESAIMS
1. To have a knowledge of visual development in childhood
2. To understand basic principles of vision testing
3. To have the ability to test vision in children
4. To identify ocular problems requiring referral to the Eye service
5. To take appropriate action regarding review and referral OUTCOMES To accurately identify and refer all children with visual problems, to the Eye service so the best visual acuity, binocular vision and cosmetic appearance can be obtained for each child.
MANDATE AND FOUNDING DOCUMENTSThis work is based on the recommendations in Best Health for Children – Developing a Partnership with Families 1999 Training of Doctors and Public Health Nurses in Child Health Surveillance 2000 It is further supported by the National Children’s Strategy 2000 National Health Strategy: Quality and Fairness – a Health System for You 2001 Investing in Parenthood to achieve best health for children 2001 National Report of Core Child Health Programme Review Group (In draft) 2004
Background to the Training Initiative
Best Health for Children (BHFC) was established by the Conjoint Body of Chief Executives of the health boards in 1999 to drive the implementation of the report, Best Health for Children – Developing a Partnership with Families. Arising from the recommendations in this report for child health screening and surveillance, BHFC published a supplementary report entitled Training for Doctors and Public Health Nurses (2000). The work of Best Health for Children is now incorporated into the wider Programme of Action for Children within the Health Boards Executive (HeBE).
Both reports can be accessed through www.hebe.ie/programmes/programmefactionforchildren.
A National Training Committee, with membership drawn from all the key stakeholders, produced a training report that was accepted by the CEOs of each Health Board in 2000. Training for Doctors and Public Health Nurses in Child Health Surveillance suggested an outline curriculum for a standardised, quality assured, evidence-based training programme for doctors and nurses involved in child health surveillance.
A national training plan for doctors and nurses involved in child health surveillance was developed. A national expert group to oversee this development was sanctioned by the Board of HeBE and started work in September 2003 to oversee the implementation of the Training Project. Joint training of regional trainers by the Department of Paediatrics TCD and PAC began in January 2004. This training is ongoing and will continue as further training needs are identified though the project’s implementation at regional level.
The National Core Child Health Programme was reviewed and updated in line with recent evidence. The revised BHFC recommendations form the basis of this manual.
VISUAL ACUITYThis is the ability to discriminate detail. Visual acuity is a measurement of the smallest image a person can see and identify at a set distance using a Snellen or equivalent chart.
AMBLYOPIA Amblyopia is defined as a reduction of visual acuity in one or both eyes. The reduced vision persists after correction of the refractive error and removal of any pathological obstruction. The essential factor to the development of amblyopia is an abnormal retinal image in one or both eyes during maturation of the visual system. It affects approximately 2.5% of the population.
SQUINT Squint is a condition in which both visual axes are not aligned correctly. A squint may be convergent (turning in), divergent (turning out) or vertically displaced.
Squints can be constant or intermittent.
It affects up to 6% of children. Most childhood squint is concomitant (in which the angle remains the same in different positions of gaze).
Squint can be the presenting sign of serious systemic and ocular disease. The eyes of a blind infant are commonly divergent.
Some common terms for squints are lazy eye, cross-eyed, boss eyed, wall eyed, turned in eye.
Beware parents may use the term “squint” to mean screwing up the eyes.
REFRACTIVE ERRORThis is the disturbance of the optical system of the eye. This leads to a blurred image being formed on the retina.
• Myopia (shortsighted) The image of an object is focused in front of the retina.
• Hypermetropia (longsighted) The image of an object is focused behind the retina. Small amounts can be overcome by focusing the lens of the eye.
• Astigmatism A mixture of refractive error at different axes, preventing a sharp retinal image to be formed. The eye is more rugby ball than football shaped.
OPHTHALMOLOGISTA doctor who specialises in the diagnosis and treatment of eye abnormalities and diseases. Most Ophthalmologists are based in hospitals. They provide medical treatment or surgical procedures as indicated.
ORTHOPTIST Orthoptists have specialised training which enables them to assess, diagnose and treat squints, amblyopia and abnormalities of binocular vision. Orthoptic treatment aims to maximise vision and relieve symptoms e.g. double vision. Orthoptists work with ophthalmologists and optometrists and are part of the eye care team.
OPTICIAN/OPTOMETRISTThese eye professionals prescribe and supply glasses. They will refer certain eye conditions to an eye specialist (Ophthalmologist) for treatment.
NEONATES The eye is large in relation to the rest of the body at birth. There is no iris pigment at birth. A baby has a fixed focal length of approximately 30cm until 4-6 weeks. All children under 31 weeks’ gestation and/or less than 1.5 kilogram’s should be checked by an Ophthalmologist for Retinopathy of Prematurity.
1-3 MONTHS The start of the critical period for the development of vision occurs within the first two months.. The eyes can converge. A defensive blink is present within the first few weeks. Squints are now abnormal, however slight.
Looks at face with preoccupation Follows slowly moving objects 4-6 MONTHS The fovea develops during the first six months and both eyes work together as a pair (binocular vision).
Vision 6/45 Visually alert for near and distance Smooth following eye movements in all directions Reaches for toys and watches objects within visual field 7-12 MONTHS Improvement of visual competence. Accommodation is at an advanced stage of development.
1-2 YEARS The cornea is adult size by 2 years. Vision can be recorded up to 6/18 at 2 years.
2-31/2 YEARS Can match single letters 3 years recorded vision 6/6 with single letters 4- 5 YEARS (SCHOOL ENTRY) Capable of Snellen visual acuity but may still require matching card.
7-8 YEARS Approaching the end of the critical period for vision development. Treatment can still be given effectively up to at least age twelve depending on the type of defect.
BARRIERS TO NORMAL VISUAL DEVELOPMENTAMBLYOPIA Amblyopia is defined as a reduction of visual acuity in one or both eyes. The reduced vision persists after correction of the refractive error and removal of any pathological obstruction. The essential factor to the development of amblyopia is an abnormal retinal image in one or both eyes during maturation of the visual system. It affects approximately 2.5% of the population.
Amblyopia can develop due to:Defocused image, e.g. refractive error Lack of light or stimulation, e.g. ptosis, cataract, retinoblastoma Abnormal binocular interaction, e.g. squint.
CROWDING EFFECTAmblyopia causes blurring of a whole line of letters so prevents the child seeing letters at the centre of the line on a chart, but they may be able to see single letters.
It is important to use a line of letters to test vision accurately. A child with amblyopia may have 6/6 with single letter vision acuity but only 6/18 when tested with a linear chart.
Stimulating the eye by giving the full optical correction and patching the good eye to give stimulation of the poor eye can reverse amblyopia up to the end of the critical period.
BEHAVIOUR OF VISUAL IMPAIRED CHILDRENPoorly sighted children exhibit no smiling to visual stimulation. They do not fix or follow a light or face. They often roll their eyes and appear to look over the viewed object. If the vision is very low they tend to stare at bright light sources, e.g. windows and lamps. If the vision is very poor, they often spend an excessive amount of time poking and rubbing their eyes.
Many children who are born blind or poorly sighted have divergent squints.
CARE OF A VISUALLY IMPAIRED CHILDVery poorly sighted children need tactile input before they are picked up, fed or changed etc. This is because they do not make eye contact or see the bottle or spoon approaching. It is thought that blind children who are not touched or spoken to before being picked up adopt very closed and defensive body language and often rock back and forth.
DEVELOPMENT OF BINOCULAR SINGLE VISION (BSV)Binocular single vision is the ability to use both eyes simultaneously so that each eye contributes to a common single perception.
REQUIREMENTS FOR THE DEVELOPMENT OF BSVOrbits of both eyes correctly aligned • Eye muscles capable of moving the eyes together • Healthy nervous system including higher centres and midbrain • Visual pathway and visual cortex intact • Optical properties of each eye are the same so they produce the same brightness, • colour, clarity and size of image
• Overlapping visual fields
B Development of central mechanisms
• Fusion - the ability to fuse 2 images as one through a range of movement
• Stereopsis - the ability to perceive depth (3D vision)