visual acuity in children

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Presentation Transcript

Visual Acuity Assessment in Children : 

Visual Acuity Assessment in Children RAJNISH KISHORE 28th August 2009

Visual Acuity : 

Visual Acuity Defined as an estimation of spatial resolution ability Only a part of visual function 1. Minimum distinguishable acuity 2. Minimum separable acuity 3. Minimum recognizable or legible acuity

Why record visual acuity in children ? : 

Why record visual acuity in children ? Most eye problems can be treated if detected early Useful in decision making To know if visual development is normal Helps decide eligibility for low vision and rehabilitation services

History : 

History In mid 1950s, with the establishment of the Allen cards, development of pediatric acuity testing techniques were reported

Age Groups : 

Age Groups Infants (Birth – 14 months) Toddlers (14 months – 21/2 years) Preschoolers (21/2 years – 5 years) School going children (5 years – 15 years)

Ability to fixate and Follow : 

Ability to fixate and Follow

Methods of testing Visual Acuity in Infants : 

Methods of testing Visual Acuity in Infants Fixation Maintain Fixation Preference Optokinetic Nystagmus (OKN) Force Choice Preferential looking test (FCPL) Visual Evoked Potential (VEP)

Fixation Maintain : 

Fixation Maintain There are two types fixations are present 1.Centric 2. Eccentric Component of Fixation C = Central S = Steady M = Maintained

Fixation Preference : 

Fixation Preference Place a 10D base down prism in front of one eye Alternate fixation indicate equal visual acuity in both eyes If fixation does not maintain then preferred eye occluded If fixation is maintained through a blink, then also visual acuity is good

Optokinetic Nystagmus : 

Optokinetic Nystagmus OKN drum consist of white and black strips rotates in front of infant’s eye Examiner has to follow the fixation movement of patient’s eye

Force Choice Preferential Looking Test : 

Force Choice Preferential Looking Test Infants prefer to fixate high contrast bold strips rather than homogenous field of light Two target and a central fixation light at infant’s eye level Examiner has to become familiar with the child’s looking style First fixation Duration of fixation Facial expression of patient

Visual Evoked Potential / Visual Evoked Cortical Potential : 

Visual Evoked Potential / Visual Evoked Cortical Potential A checkerboard stimulus phase altered at a rate of 6 cycle/sec in front of the patient’s eyes A electrode placed on skull over occipital lobe Result is compared with the VEP of adult

Methods of testing Visual Acuity in Toddlers : 

Methods of testing Visual Acuity in Toddlers Hundred and Thousand Sweet Test The Cardiff Acuity Test Dott Visual Acuity Testing

Hundred and Thousand Sweet Test : 

Hundred and Thousand Sweet Test A very sweet test If child able to pick up small sweets at 33 cm, visual acuity is at least 6/24 or 20/80

The Cardiff Acuity Test : 

The Cardiff Acuity Test The principle of the target design is that of the vanishing optotype The targets are pictures drawn with a white band bordered by two black bands, all on a neutral grey background The examiner simply observes the child’s fixation

Dott Visual Acuity Testing : 

Dott Visual Acuity Testing Black dots on white background Touch a black dot Test dist--25 cm VA--20/800 to 20/20

Administration of Tests in Preschoolers : 

Administration of Tests in Preschoolers Step 1 A pretest to teach and check the child's reliability in responding to the test Step 2 A test to assure that the child’s responses are reliable at 10ft (3m) Step 3 Actual measurement of acuity level at 10ft (3mt)

Methods of testing Visual Acuity inPreschoolers : 

Methods of testing Visual Acuity inPreschoolers LEA Symbols Light House Flash and Card Testing Allen Picture Card Broken Wheel Test Tumbling E chart Landolt C chart Sjogren hand test HOTV test

LEA Symbols test : 

LEA Symbols test Task is to match and point out the distance target 10 feet distance pictures--circle square house apple

Light House Flash Card Testing : 

Light House Flash Card Testing 12 cards are available, size of each card is 4×5 inch These cards have three types of picture target Target size available from 20/200 – 20/10 In 20/200 card we have 20/100 target size on the reverse side

Allen Picture Card : 

Allen Picture Card Here 6 pictures have been used --Horse, Bird, Cake, Hand Car and Telephone Card size : 4 × 4 inch with white background

Broken Wheel Test : 

Broken Wheel Test Here cards are presented with picture of a car, very familiar to the child Two cards are held before the child, he simply has to recognize which one is broken It consist of 8 pairs of test cards and a sample pair of card (equivalent to 20/120 test size)

Tumbling E chart : 

Tumbling E chart English E letter is used in different directions The child has to detect the orientation of the limbs Simons introduced use three directions to avoid confusion

Landolt C chart : 

Landolt C chart Sjogren hand test

HOTV Test : 

HOTV Test Optotypes are used to avoid left right confusion Child has to identify the letter optotypes

Methods of testing Visual Acuity inSchool going children : 

Methods of testing Visual Acuity inSchool going children Tumbling E chart Landolt C chart Sjogren hand chart Snellen’s chart Log Mar Chart

Snellen’s chart : 

Snellen’s chart 7 diff size levels 1 letter at largest size level & no. at each size level increases No log progression

Log Mar Chart : 

Log Mar Chart A logarithmic size progression Same no. of letters at each level Between letter & between row spaces proportional to letter size Good legibility for optotype at each level

Evaluation of Binocular Vision : 

Evaluation of Binocular Vision Binocular vision of children is been greatly affected in presence of strabismus Direction Frequency Magnitude Laterality AC/A ratio Cosmesis

Sequence of Testing for Binocular Alignment : 

Sequence of Testing for Binocular Alignment Observation Hirschberg Test Krimsky Test \ Prism Bar Reflex Test Bruckner Test Cover Test

Observation : 

Observation Optometrist should be looking for obvious stimulus Pseudo esotropia -Epicanthic folds -Short inter pupillary distance - negative angle Kappa Pseudo exotropia -Wide inter pupillary distance -Positive angle Kappa

Hirschberg Test : 

Hirschberg Test Patient has to fix the penlight of the examiner, held at 50cm Examine the corneal reflex in relation to the centre of the pupil

Krimsky Test \ Prism Bar Reflex Test : 

Krimsky Test \ Prism Bar Reflex Test Helpful for estimating the magnitude of infant’s strabismus, cause poor vision

Bruckner Test : 

Bruckner Test Illuminate infant’s both eyes with a direct ophthalmoscope from1mt By comparing the reflexes examiner can evaluate binocular alignment

Cover Test : 

Cover Test Direct cover test Cover uncover test Alternate cover test

ENVIRONMENT ADJUSTMENT : 

ENVIRONMENT ADJUSTMENT Reception area--small chairs toys games puzzles Scheduling appt—Child’s daily rhythm. Small but meaningful changes

Slide 42: 

Normal wallpapers --familiar cartoons choose to conduct exam--without white coat--reduce the appearance of ophthalmic equipment

Slide 43: 

“Thank Y0U” SHIV AAJ BHI GURU HAI