VISUAL ACUITY IN PRESCHOOL CHILDREN

Zarin khanB.Optom

VISUAL ACUITY

It is the resolving power of the eye. It is an ability to see two separate object as separate.

VISUAL ACUITY IN PRESCHOOL CHILDERN

OIn preliterate but verbal children, VA as defined as the smallest target of known size at known testing distance correctly verbally identified by a child.

OUse of the Landolt C format.OUse of single, isolated optotypes, rather

than a full line or chart.OA two-alternative force choice or

matching response.OAvoidance of the need for a verbal

response or a directional response.OA short test distance such as 3 meters,

rather than traditional 6 meters distance.

Desirable characteristics for preschool visual acuity test

O Very soon after birth - Can fix and follow a light source, face or large, colorful toy.

O 1 months - Fixation is central, steady and maintained, can follow a slow target, and converge, preference of looking at face.

O 3 months - binocular vision and eye cordination, eyes follow a moving light or face, responsive smile.

O 6 months - Reaches out accurately for toys.O 9 months – look for hidden toys.O 2 years - Picture matchingO 3 years - Letter matching of single letters (e.g., Sheridan

Gardiner)O 5 years - Snellen chart by matching or naming

VISUAL MILESTONES

Infants (Birth – 14 months)Toddlers (14 months – 21/2

years)Preschoolers (21/2 years –

5 years) School going children (5

years – 15 years)

Age Groups

Visual acuity chart for pre-school children

VISION TEST IN 3-5 YEARSO Illiterate E- cutout testO Tumbling ‘E’ testO Isolated hand figure testO Sheridan –Gardiner HOTV testO Pictorial vision chartO Broken wheel testO Boek candy bead test

O Light house picture cards.O Stycar visual acuity test .O Lea symbol .O Kay picture test. O Cardiff chart .O Allen card test . O Landolt ‘c’ or ring chart

Vision test in 2-3 yearsO Dot acuity testO Coin testO Miniature toy test

Vision test in 1-2 yearsO Marble game testO Sheridan’s ball testO Boek’s candy testO Worth’s ivory ball test

Vision tests in 3-5 years

children

ILLITERATE E-CUTOUT TEST

O It is used with children about 2 ½ -5 years of age

O The child is given a cut out of an E & asked to match this E with isolated Es with varying sizes.

O The first trial is not always successful.O The mother may be instructed to teach E-game

at homeO When the children starts understanding the

orientation of E, a visual acuity chart consisting of Es oriented in various directions may be used.

O When the children starts understanding the orientation of E, a visual acuity chart consisting of Es oriented in various directions may be used.

Tumbling ‘E’ chart O It consists of letter ‘E’O It has different sizes of E in one of the

four position( Right, left, upward & downward)

O The test is done at a distance of 6 meter.O The child is given wooden or plastic letter

E and is asked to point the direction of E as instructed by the examiner .

O Or the patient is directly told to point the finger in the direction up down ,left, right as shown in the main chart .

O It is similar to E- cutout test.

Tumbling ‘E’ chart

Isolated hand figure test

OSjogren has replace the E with the isolated figure of a hand & in some children it works better than Es.

SHERIDAN GARDINER HOTV TEST

O It is used for the age group of 2-5yrs .

O It is done at 6 meter and if child can’t read 6/60 we can do it at 3 meter .

O The chart is available in the form of spiral booklet .

O The main chart consists of letters HOTV of different size .

OThese letters are arranged may be in circular form to give proper orientation so that child can identify them properly .

OThe child is given a key card and is asked to match with the letter as shown in the main card.

OThe four letter ‘HOTV’ are only used as they are considered as standard letters for measuring visual acuity .

OMore over it is found that these letters are more child friendly .

STYCAR VISUAL ACUITY TEST

O It is done at a distance of 10 to 20 foot distance .

OThe main chart consist of pictures of eating items or toys .

OThe child is given a key card and is asked to match with the pictures as shown in the main chart by the examiner .

LEA SYMBOL CHARTO It is done at a distance of 3meter.O The chart is available in simple as

well as spiral booklet form .O The main card consist of 5 symbols

with one symbols in centre and the rest 4 are located in circular form around the central symbol .

O These arrangement is done in particular to develop both crowding and confusing phenomenon for the child difficulty .

O The examiner shows normally centre symbol but at the same time he can ask for other symbols too.

O The patient is given a key card to point out the symbol .

O These symbols are fixed and are kept a standard like apple ,house ,circle ,square etc ..

O The size of pictures goes on decreasing from 3/9.5 to 3/2.4 and there are four cards for each size .

KAY PICTURE TEST O It is used for children of 2-3 yrs .O The test is done at distance of 6 meter .O It is based on snellen principle .O The chart is in the form of spiral booklets .O Each page has a single picture .O The size goes on decreasing from 6/60 to

6/6 with each size having 3 cards.O Again the patient is given a key card and

is asked to match with the picture as shown in the main chart .

KAY PICTURE TEST

ALLEN CARD TESTO It is done at a distance of

3 meter .O It consist of a set of seven

card with each card containing a single picture .

O It is usually used for 2 yrs old child and older

O The child is first shown cards at close range with both eyes open and is asked to name each picture .

O Then one eye of patient is occluded the examiner shuffles the cards and presents them individually over greater distances.

O The picture are of familiar objects so that the child can name them properly .

LANDOLT ‘C’ CHART

O It is usually used for age group of 3 to 6 yrs who cannot recognize letters .

O The chart consist of broken circles with each broken ring subtending an angle of 5 min at nodal point .

O The chart is shown to the patient at a distance of 6meter .

Landolt ‘c’ chart

O The patient has to identify the part from where the ring is broken by pointing the direction up ,down ,left , right by finger .

O Landolt ‘c’-chart based on log MAR principle are also available .

O They consist of 5 rings per line and the size goes on decreasing as we move a head .

OConsist of 8 pair of test cardsO20/20, 20/25, 20/30, 20/40, 20/60,

20/80, 20/100, 20/120.OEach card has a black line drawing of a

car on a white background.O1 with solid wheels , other with broken

wheels. ODone from 3m distance

Broken wheel test

Clinical procedureO 2 cards are held before the childO He simply identify which one is broken wheelO If the child can distinguish which car has the

broken wheels,it indicates that he can resolve the gap size of the landolt C for the particular card

O If acuity is less than 20/120,steps are repeated at 1.5m distance

O Visual acuity is recorded as the last set of cards at which the child correctly respond.

Light home picture cardOA chart containing an apple, a house and an umbrella, arranged in OSnellen’s equivalents of 20/200-20/10 is used, andO The child is asked to identify the pictures along the lines.O The test is carried out at 10 ftO12 cards are available, size of each card is 4×5

inch

Vision tests in 2-3 years children

O Black dots on white background O Touch a black dotO Test dist--25 cmO VA--20/800 to 20/20 PROCEDURE…….O Child is shown an illuminated box with black

dots of different sizes printed on itO The smallest dot identified denotes the visual

acuity of the child

Dot visual acuity test

OThe child is asked to identify the 2 faces of coins of different sizes held at different distances.

Coin test

Miniature toy test

Procedure:

In this test the child are shown a miniature toy from a distance of 10ft .

Asked to name or pick the pair from the assortment.

Vision tests in 1-2 years children

Marble game test In children of 1-2 years of age

reaching or placing games can be used to estimate visual function.

The game is the marble game.

This test is not intended to measure visual acuity of each eye.

Procedure: The child is asked to place marbles ln the

holes of a card or in a box.

Compare the functioning of the childs eye when one or the other is closed.

The vision of an eye is then noted as

being useful or less useful.

Sheridans ball test Mary Sheridan used a series of Styrofoam

balls of progressively smaller size. Procedure

One record the smallest ball that the infant can fixate and follow at a distance of 10ft.

Rolling the ball on a white or grey background and asking the child to pick it up.

Continue…………

Noting the smallest size to which the child gives a good response is a rough way of estimating visual acuity.

Worth ivory ball test

OProcedure

Ivory balls 0.5 to 2.5” in diameter are rolled on the floor in front of the child and he is asked to retrieve each.

Visual acuity is estimated on the basis of

smallest size for the test distance.

References…

O Theory and practice of optics and refraction—A.K Khurana

O Clinical visual optics.

O Clinical procedure of optometry

O Internet.

Thanks to all…