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VISUAL IMPAIRMENT

We are born with low vision, but it improves rapidly during the first weeks of life as the retina, visual pathways and visual cortex develop. When an infant is held upright, he will try to turn his head and eyes towards a large light source or window. He is especially interested in the human face and looks intensively into the eyes of adults.

Accommodation and convergence may be executed by the newborn and adult – like accommodation is possible at 2-3 months of age. It is also sufficiently controlled for the infant to study his hand, and later he will intentionally bring the hand close to his eyes. Visual acuity is about 6/60 at 2-3 months of age and close to an adult’s 6/6 at 6 months of age. Small objects interest the infant within a visual sphere of 1-1.5m.

Visual acuity measures vision in the centre of the retina. There is also rapid development of the visual pathways and visual cortex in the brain. Visual acuity of an eye may decrease if an eye is not used. It is thus important that abnormalities from normal development are recognised and treated promptly.

At the age of 2-4 years a child uses his vision for increasingly demanding tasks at near distance. It would now be possible to measure visual acuity with pictures designed for this purpose.
Contrast sensitivity is poor at birth and improves rapidly during the first year of life and reaches adult level at three years of age. At two months old the child’s sensitivity to colours of the spectrum resembles that of an adult.

At three months of age the child reacts to objects in only the central 60 degrees of his visual field, but are able to use the whole 180 degrees of the visual field. The reactions on both sides of the visual field are symmetric.

Vertical tracking movements usually appear at the age of four to eight weeks. Movements are poorly controlled and jerky, but should be perfected by the end of the first year of life.

VISION SCREENING IN PRE-SCHOOL CHILDREN

AGE

OBSERVATION

Newborn

Pupillary reaction

0-3 months

Development of ocular movements

Eye contact

Social smile

4-6 months

Looks at hands

Hands to midline

Recognises distant objects

7-10 months

Peripheral vision symmetrical

Notices bread crumbs

Pincer grasp

1-2 years

Recognises people at a distance

Interested in books and pictures

3-4 years

Names pictures near and at a distance

5-6 years

Adult-like vision but difficulties with crowded visual information.

WARNING SIGNS THAT MAY INDICATE VISUAL IMPAIRMENT
  • Infants – 1 year of age
  • no steady eye contact
  • a constant crossing of the eyes
  • one eye that turns out
  • inability to track an object moving across their field of vision
WARNING SIGNS FOR THE PRE-SCHOOL CHILD
  • misaligned eyes
  • the presence of a white pupil
  • sudden development of pain and redness in one or both eyes
WARNING SIGNS AT ANY AGE

No matter how old your child is, consult your paediatrician on any one of the following:

  • eyes flutter quickly from side to side
  • eyes are always watery
  • eyes are always sensitive to light
  • any changes from their usual appearance
  • white, greyish or yellow material in the pupil
  • redness in either eye that doesn’t go away in a week
  • continued pus or crust in either eye
  • eyes that turn out or don’t focus together
  • continuous rubbing of the eyes
  • squinting
  • tilting or turning of his head to focus
  • drooping eyelids
  • eyes appear to bulge
WHEN SHOULD YOUR CHILD'S EYES BE CHECKED
  • shortly after birth
  • during health supervision visits
  • children with a family history of vision problems
  • Ask your doctor to refer you to an eye specialist as soon as a problem is detected
COMMON EYE & OTHER TERMINOLOGY

accommodation: increase in optical power to maintain a clear image as objects are moved closer

acuity: measure of eye’s ability to distinguish object details and shape

agnosia: inability to recognise common objects regardless of visual acuity

albinism: congenital defect, lack of pigment in eyes, hair and skin, associated with decreased acuity and light sensitivity

Albright’s disease: pathologic, pigmented skin lesions, early puberty, bone abnormalities, visual field defects, protrusion of eyes

Alport’s syndrome: pathologic condition, hereditary disorder, deafness, kidney disease, lens abnormalities

amblyopia: lazy eye, functional defect, decreased vision in one or both eyes without anatomic damage in eye or visual pathways. Uncorrectable by optical means

aphakia: one whose lens has been removed

aqueous humor: clear watery fluid that fills the space between back corneal surface and front vitreous surface, bathing the lens

astigmatism: refractive error, optical defect in which refractive power is not uniform in all meridians

autism: developmental disorder characterised by problems in communication, socialisation, sensory sensitivity and abstract meaning

Best’s disease: pathologic condition, degeneration affecting macular area. Lesion has appearance of egg yolk

blepharitis: inflammation of eyelid margins

blepharospasm: involuntary spasms of the eyelid, producing uncontrolled blinking

blindness: inability to see. Legal blindness: a best corrected acuity to 6/60 or less, or a reducton in visual field to 20 degrees or less in the better seeing eye

cataract: opacity or cloudiness of the lens, may be congenital or caused by trauma, disease or age

coloboma: congenital anomaly. Cleft or defect in normal continuity of part of the eye

cone dystrophy: functional defect. Hereditary degeneration of retinal receptors. Results in progressive, markedly decreased vision and loss of colour discrimination. No known treatment

conjunctivitis: inflammaton of mucous membrane that covers the white of the eye and inner surface of the eyelids. Characterised by discharge, grittiness, redness and swelling.

cortical blindness: loss of vision in an apparently normal eye caused by damage to the visual cortex of the brain

diplopia: double vision. Perception of two images from a single object

Duane’s syndrome: congenital defect. Eye abnormality accompanied by inward eye deviation

dyslexia: specific reading disability, problems in interpreting written symbols. not related to visual acuity or intelligence

eccentric fixation: visual abnormality in which retinal area other than fovea centralis is used for visual fixation

esotropia: misalignment of eyes in which one eye deviates inward

evisceration: removal of the eyeball’s content, leaving the scleral shell intact

exopthalmos: abnormal bulging forward of the eyeball

exotropia: misalignment of the eyes in which one eye deviates outward

farsightedness: refractive error

fetal alcohol syndrome: congenital abnormality found in babies born to mothers using alcohol, delayed growth, mental retardation, eye abnormalities, behavioural problems

glaucoma: pathological condition. Increased intra ocular pressure. A common cause of preventable vision loss

Goldenhar syndrome: congenital anomaly. Ear and sine deformities, feafness and eye findings ##

keratitis: pathological condition, inflammation of the cornea, loss of luster and transparency

keratoconus: pathological condition, generalised thinning and cone shaped protrusion of central cornea

Leber’s amarausis: congenital defect, bilateral blindness or near blindness in young children, nystagmus, sensitivity to light, sunken eyes

Leber’s optic atrophy: degenerative process affecting both eyes, rapidly progressive optic nerve degeneration occurring in young men

macrophthalmos: anatomic defect, abnormally large eyeball

macular degeneration: pathological condition, retinal degeneration leading to permanent loss of central vision

Marfan’s syndrome: pathological condition, connective tissue disease, relaxed ligaments, joint deformities, heart disease and dislocated lenses

myopia: refractive error, nearsightedness

neovascularisation: pathologic condition, abnormal formation of new blood vessels

night blindness: functional defect, ineffective dark adaptation resulting in reduced vision in dim illumination

nystagmus: functional defect, involuntary side to side or up and down movement of the eyes

occlusion: covering one or both eyes

retinal detachment: pathologic condition, seperation of retina from underlying epithelium, markedly disrupts vision

retinitis pigmentosa: pathologic condition, progressive degeneration in both eyes, night blindness develops, followed by loss of peripheral vision and finally blindness

retinablastoma: pathologic condition, malignant intraocular tumor filling the eye, extending along the optic nerve to the brain, ending in death

retinopathy of prematurity: pathologic condition, destructive retinal changes after prolonged oxygen therapy to premature infants. Can result in vision loss or blindness, complications are glaucoma, cataracts, sunken eyes and eye misalignment

retinoschisis: degenerative change, abnormal splitting of retinal sensory layers resulting in loss of function

Rubella syndrome: pathologic condition, viral infection contracted during pregnancy, resulting in fetal abnormalities. Mental retardation, heart disease, hearing defects, eye lesions

scotoma: functional defect, non seeing area within visual field occuring with damage to retinal pathways

Snellen chart: test chart for assessing visual acuity. Rows of letters, numbers or symbols in standardized graded sizes. Tested at 6m at which each row should be legible to a normal eye

squint: functional defect, misaligned eyes caused by extraoccular muscle imbalance

Stevens Johnson syndrome: pathologic condition, severe conjunctival disease in patients with erithema multiforme

Still’s disease: pathologic condition, juvenile rheumatic arthritis, inflammation of the iris

strabismus: functional defect, misalignment of both eyes inward or outward

Usher’s syndrome: pathologic condition, retinal degeneration accompanied by nerve deafness

vitrectomy: surgical procedure by which vitreous, blood, membranes are removed from the eye

LEES MEER

VISUEELGESTREMDHEID

Ons word met laevisie gebore, maar dit verbeter vinnig in die eerste paar weke na geboorte soos die retina, visuele bane en visuele korteks ontwikkel. Wanneer ‘n baba regop gehou word, sal hy probeer om sy kop en oë na ‘n groot ligbron of venster te draai. Hy stel veral belang in die menslike gesig en kyk gewoonlik stip in die oë van volwassenes.

Akkommodasie en konvergensie vind reeds plaas by ‘n pasgebore baba en akkommodasie soos by volwassenes is reeds moontlik op 2-3 maande. Dit word genoegsaam beheer vir die baba om sy eie hand te bestudeer, en hy sal later sy hand naby aan sy oë bring. Gesigskerpte is ongeveer 6/60 op 2-3 maande en baie na aan ‘n volwassene se 6/6 teen 6 maande. Klein voorwerpe binne ‘n visuele sfeer van 1-1.5m sal die baba interesseer.

Gesigskerpte meet die visie in die middel van die retina. Daar is ook snelle ontwikkeling van die visuele bane en visuele korteks van die brein. Gesigskerpte mag afneem indien ‘n oog nie gebruik word nie. Dit is dus belangrik dat abnormale ontwikkeling herken en dadelik behandel word.

Op die ouderdom van 2-4 jaar gebruik ‘n kind sy visie vir toenemend moeiliker take binne ‘n kort afstand. Dit is nou moontlik om gesigskerpte te meet met prente wat daarvoor ontwerp is. Kontrassensitiwiteit is swak by geboorte, maar verbeter vinnig en is op volwasse vlak teen 3 jaar. Op 2 maande stem die kind se sensitiwiteit vir alle kleure van die spektrum ooreen met die van ‘n volwassene.

Op 3 maande regaeer die kind slegs op voorwerpe in die sentrale 60 grade van sy gesigsveld, maar hy kan die volle 180 grade van sy gesigsveld gebruik. Die response op beide kante van sy gesigsveld is simmetries.

Vertikale volgbewegings verskyn gewoonlik op 4-8 weke. Dit word swak beheer en is rukkerig, maar behoort aan die einde van die eerste lewensjaar bemeester te wees.

VISUELE SIFTING IN VOORSKOOLSE KINDERS

OUDERDOM

WAARNEMING

Pasgebore baba

Pupillêre refleks
0-3 maande

Ontwikkeling van okkulêre bewegings

Oogkontak

Sosiale glimlag

4-6 maande

Kyk na hande

Hande na middellyn

Herken voorwerpe wat verder geleë is

7-10 maande Perifere visie simmetries

Sien broodkrummels raak

Knypgreep

1-2 jaar

Herken mense op ‘n afstand

Stel belang in boeke en prente

3-4 jaar

Benoem prente naby en ver

5-6 jaar

Volwasse sig maar probleme met beknopte visuele inligting

WAARSKUWINGSTEKENS VAN VISUELE INPERKING
  • Babas – 1 jaar
  • geen vaste oogkontak
  • konstante kruiskyk van die oë
  • een oog wat uitdraai
  • onvermoë om ‘n voorwerp wat oor hul gesigsveld beweeg, te volg
WAARSKUWINGSTEKENS IN DIE VOORSKOOLSE KIND
  • skeelkyk
  • voorkoms van ‘n wit pupil
  • wanneer pyn en rooiheid skielik in een of albei oë voorkom
WAARSKUWINGSTEKENS OP ENIGE OUDERDOM

Ongeag die ouderdom van jou kind, raadpleeg ‘n pediater oor enige van die volgende:

  • oë fladder vinnig van kant tot kant
  • oë is altyd waterig
  • oë is altyd sensitief vir lig
  • enige verandering in hul normale voorkoms
  • wit, grys of geel materiaal in die pupil
  • rooiheid in enige oog wat langer as ‘n week voortduur
  • voortgesette etter of aanpaksel in enige oog
  • oë wat uitdraai of nie saamfokus nie
  • voortdurende vryf van die oë
  • skeelkyk
  • kanteling of draai van kop om te fokus
  • slap ooglede
  • oë wat lyk of dit uitpeul
  • squinting
  • tilting or turning of his head to focus
  • drooping eyelids
  • eyes appear to bulge
WANNEER MOET ‘n KIIND SE Oë GETOETS WORD
  • kort na geboorte
  • gedurende gesondheidskontrolebesoeke
  • kinders met ‘n familiegeskiedenis van visieprobleme
  • Vra u dokter om u na ‘n oogspesialis te verwys sodra ‘n probleem geïdentifiseer word.
ALGEMENE OOG- EN ANDER TERMINOLOGIE

afakie: wanneer die lens verwyder is

agnosie: onvermoë om eenvoudige voorwerpe te herken ten spyte van gesigskerpte

akkommodasie: toename in optiese vermoë om ‘n duidelike beeld te behou soos voorwerpe nader beweeg

albinisme: kongenitale defek, gebrek aan pigment in oë, hare en vel, geassosieer met verlaagde gesigskerpte en ligsensitiwiteit

Albright se siekte: patologies, gepigmenteerde velletsels, vroeë puberteit, beenabnormaliteite, probleme met gesigsveld en uitpeuloë

Alport se sindroom: patologiese toestand, oorerflike siekte, doofheid, niersiekte, lens-abnormaliteite

ambliopie: lui oog, funksionele defek, verminderde sig in een of albei oë sonder anatomiese skade in oog of visuele bane. Kan nie deur bril gekorrigeer word nie

astigmatisme: refraksiefout, optiese defek waar refraktiewe vermoë nie uniform in alle rigtings is nie

Best se siekte: patologiese toestand, degenerasie wat makulêre area affekteer. Letsel het voorkoms van eiergeel

blefaritis: ontsteking van ooglidgrense

blefarospasma: onwillekeurige spasmas van die ooglid wat onbeheersde oogknip ontlok

blindheid: onvermoë om te sien. Wettige blindheid: beste gekorrigeerde gesigskerpte van 6/60 of minder, of ‘n vermindering tot 20 grade of minder in die gesigsveld van die beter oog

diplopie: dubbelvisie. Persepsie van twee beelde vanaf een voorwerp

disleksie: spesifieke leesprobleem, probleme met interpretasie van geskrewe simbole. Nie verwant aan gesigskerpte of intelligensie nie

Duane se sindroom: kongenitale defek. Oogabnormaliteit tesame met afwyking van oog wat indraai

eksentrieke fiksasie: visuele abnormaliteit waar retinale area buite die fovea centralis vir visuele fiksasie gebruik word

eksoftalmos: abnormale uitpeul van die oogbal

eksotropie: wanbelyning van die oë waar een oog buitentoe draai

esotropie: wanbelyning van oë waar een oog binnetoe draai

eviserasie: verwydering van die oogbol se inhoud maar geen skade aan die sklera-dop

fetale alkohol sindroom: kongenitale abnormaliteit in babas wat gebore is van moeders wat alkohol misbruik het, vertraagde groei, verstandelike gestremdheid, oogabnormaliteite, gedragsprobleme

gesigskerpte: maatstaf van die oog se vermoë om die details en vorm van voorwerpe waar te neem

gloukoom: patologiese toestand. Verhoogde intraokkulêre druk. Algemene oorsaak van voorkombare sigverlies

Goldenhar sindroom: kongenitale anomalie. Oor- en sinus-misvormings, doofheid en oogprobleme

katarak: ondeursigtigheid of melkerigheid van die lens kan kongenitaal wees of veroorsaak deur trauma, siekte of ouderdom

keëltjiedistrofie: funksionele defek. Oorerflike degenerasie van retinale reseptore. Lei tot progressiewe, merkbare verminderde sig en verlies van kleurdiskriminasie. Geen behandeling bekend

keratitis: patologiese toestand, ontsteking van die kornea, verlies aan helderheid en deursigtigheid

keratokonus: patologiese toestand, algemene verdunning en keëlvormige uitstaan van sentrale kornea

koloboom: kongenitale anomalie. Spleet of defek in normale eenheid van ‘n deel van die oog

konjunktivitis: ontsteking van slymvliesmembrane wat die wit van die oog en die binneste oppervlak van die ooglede bedek. Gekarakteriseer deur afskeidings, grinterigheid, rooiheid en swelling.

kortikale blindheid: verlies aan sig in ‘n skynbaar normale oog veroorsaak deur skade aan die visuele korteks in die brein

Leber se amarose: kongenitale defek, bilaterale blindheid of amper blindheid in jong kinders, nistagmus, ligsensitiwiteit, gesonke oë

Leber se optiese atrofie: degeneratiewe proses wat albei oë affekteer, vinnige progressiewe degenerasie van optiese senuwee in jong mans

makroftalmos: anatomiese defek, abnormaal groot oogbol

makulêre degenerasie: patologiese toestand, retinale degenerasie wat lei tot permanente verlies aan sentrale visie

Marfan se sindroom: patologiese toestand, bindweefselsiekte, slap ligamente, misvorming van gewrigte, hartsiekte en gedislokeerde lense

miopie: refraksiefout, bysiendheid

nagblindheid: funksionele defek, oneffektiewe aanpassing in donkerte wat lei tot swak visie in dowwe lig

neovaskularisasie: patologiese toestand, abnormale vorming van nuwe bloedvate

nistagmus: funksionele defek, onwillekeurige heen en weer of op en af beweging van die oë

okklusie: maak een of albei oë toe

outisme: ontwikkelingstoestand gekarakteriseer deur probleme met kommunikasie, sosialisering, sensoriese sensitiwiteit en abstrakte betekenis

Retinablastoom: patologiese toestand, kwaadaardige intraokkulêre tumor wat die oog vul en langs die optiese senuwee tot die brein verloop, lei gewoonlik tot die dood

Retinale skeur: patologiese toestand, wegskeur van retina vanaf onderliggende epiteel wat visie merkbaar verswak

retinitis pigmentosa: patologiese toestand, progressiewe degenerasie in beide oë, nagblindheid ontwikkel, gevolg deur verlies aan perifere visie en uiteindelik blindheid

retinopatie van prematuriteit (ROP): patologiese toestand, vernietigende retinale veranderings weens verlengde suurstofterapie aan premature babas. Dit kan lei tot sigverlies of blindheid, komplikasies is gloukoom, katarakte, gesonke oë en wanbelyning van oë

retinoskise: degeneratiewe verandering, abnormale verdeling van retinale sensoriese lae wat lei tot verlies aan funksionering

Rubella sindroom: patologiese toestand, virusinfeksie opgedoen tydens swangerskap, lei tot fetale abnormaliteite. Verstandelike inperking, hartsiekte, gehoorverlies, oogletsels

skeelkyk: funksionele defek, wanbelynde oë veroorsaak deur ekstraokkulêre wanbalans

skotoom: funksionele defek, area binne gesigsveld ontvang geen visie, met skade aan retinale bane

Snellen-kaart: toetskaart om gesigskerpte te assesseer. Rye letters, nommers of simbole in gestandaardiseerde gegradeerde groottes. Word getoets op 6m waar elke ry leesbaar behoort te wees vir ‘n normale oog

Stevens Johnson sindroom: patologiese toestand, erge siekte van die konjunktiva in pasiënte met erithema multiforme

Still se siekte: patologiese toestand, kinder rumatoïde artritis, ontsteking van die iris

strabisme: funksionele defek, wanbelyning van albei oë na binne of buite

Usher se sindroom: patologiese toestand, retinale degenerasie tesame met senuwee-doofheid

vitrektomie: chirurgiese prosedure waar watervog, bloed of membrane uit die oog verwyder word

versiendheid: refraksiefout

watervog: helder waterige vloeistof in die ruimte tussen die agterste korneale oppervlak en voorste glasvog wat die lens omspoel