Worth 4 dot test

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The Worth of Four Light Test , also known as the Worth's Four Dot test or W4LT , is a clinical test that is primarily used to assess the degree of vision vision and vision patients single vision binoculars. The vision of binoculars involves images projected by each eye simultaneously into an area in space and fused into a single image. The Worth Four Light Test is also used in detecting suppression of either the right or left eye. Suppression occurs during binocular vision when the brain does not process information received from one eye. This is a common adaptation for strabismus, amblyopia and aniseikonia.

The W4LT can be performed by examiners at two distances, near (at 33 cm from the patient) and distant (at 6m from the patient). In both distance tests, the patient should wear red-green glasses (with one red lens above one eye, usually right, and one green lens on the left). When performing the test in distant places (distance) the W4LT instrument consists of a silver box ( mounted on the wall in front of the patient), which has 4 lights in it. The four lamps are arranged in diamond formations, with red lights on top, two green lights on both sides (left and right) and white light on the bottom. When performing the test on the close (at 33 cm) the 4 lights are arranged in exactly the same way (diamond forming), with the difference being that near, the 4 lights are located on hand instruments similar to torch light.

Since the red filter blocks the green light and the green filter blocks red light, it is possible to determine whether the patient is using both eyes simultaneously and in a coordinated way. With both eyes open, a patient with normal binocular vision will appreciate four lights. If patients close or press their eyes they will see two or three lights. If the patient does not combine the image of both eyes, they will see five lamps (diplopia).

Video Worth 4 dot test

Indications to use

The Worth Four Light Test is indicated for use when assessing binocular function, the ability of the eye to work in coordination, of an individual. This can be used to develop a diagnosis or to support or confirm the initial diagnosis. This can be used when looking to assess whether the individual has a single normal or abnormal binocular single vision response (BSV). This can be used to determine whether a patient has the ability for the eye to combine the received light from each eye into four lights. This test is indicated by the use of the presence of a prism in individuals with strabismus and fusion considered to be present if 4 lights are maintained, with or without the use of a prism. The W4LT can also be indicated when helping one to develop and strengthen their fusional capacity.

If the image can not coalesce, W4LT is still indicated to help determine whether a person values ​​diplopia (double vision) or suppresses images from one eye. In the case of real strabismus, tests may help determine the nature and type of diplopia or suppressed eye. Therefore, it is indicated in the case of suspected central suppression scrotoma because it can be used to detect where light may be unappreciated from the eye with a scotoma although in some cases minimal deviation in the eye as indicated in normal microscale 4 lamp responses may be reported. Although it can be used in these patients to prove the existence of peripheral fusion and that they have bi-foveal fixation.

Other indications for the test include setting the dominant dominant eyes of the individual eye compared to the others and when evaluating the reduced visual acuity of the eye that does not show improvement on pinhole testing.

Although there is no contraindication of W4LT it is necessary to be careful in interpreting individual results with BSV under natural conditions as they may demonstrate a diplopia response under dissociation of the test. Also in individuals who have abnormal retinal correspondence (ARC) they may provide unexpected responses, and those who have unequal visual axes that are in natural suppressive conditions may actually respond to diplopia after testing.

Maps Worth 4 dot test

Assessment methods

The Worth Four Light Test is relatively easy to do. First of all, you should place the red/green glasses over the patient's eyes, with red goggles traditionally placed over the right eye.

Next you have to dim the room lighting. This allows the patient to see the lights better.

For distance measurements, you should prepare the patient as far as six meters from the light source. For close-up measurements, tests should be performed at about one-third of a meter, or thirty-three centimeters, with a hand-held Worth's Four Lights torch.

Then ask the patients what they see. They should respond with "I see... the number of lights" as long as they have understood what you are asking them. Ask them to describe the lights to you. You should ask about the color of the lamp. If they see five lights, ask if the green dots are higher or lower than the red dots. Ask about the position of the dots, such as the red dot to the left or right of the green dots. Also ask if the dots are blinking and off or switching between red and green.

This set of questions is important to make sure you correctly record what the patient sees, so that the doctor can interpret the patient's results and then make an accurate diagnosis.

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Record and interpret results

When recording results for W4LT, it is important to ask a series of questions to the patient to make sure you record correctly what they see. It's important to interpret patient outcomes and then make an accurate diagnosis.

The question is:

1. How many lights do you see?
2. What's the color? Where are they located?
3. Are all lights right? Or is there something higher than the others?
4. Did all the lights appear at a time, or did they turn on and off?

When recording the results, it is important to show the test used, the description of the light being viewed and the indication of what the result means. It is also important to record the distance at which the test is performed and whether the patient is using refractive correction itself or not.

Where communication is difficult between doctors and patients, such as in the presence of language barriers, or when working with a child, it may be a good idea to get patients to draw what they see. Clinicians can then interpret the results of the drawing.

Results

There are a number of possible results shown by W4LT

Normal retinal correspondence

With no deviation, the patient will see the lights exactly as they appear. When asked they will report that:

• They see 4 lights, 1 red, 2 green and one blend color
• Two green lights will be on both sides with a little red light above them and mixed color light under red

These are recorded as: W4LT (D): 4 lamps (BSV)

Abnormal retina correspondence

This will be shown in the closing test that the patient has a real aberration. When asked about the lamp, the patient will give a normal response and will see the lights exactly as seen. They will report that:

• They see 4 lights, 1 red, 2 green and one blend color
• Two green lights will be on both sides with a little red light above them and mixed color light under red

These are recorded as: W4LT (D): 4 lights (ARC)

NB: ARC can only be confirmed along with additional clinical tests for retinal correspondence. Patients should show significant deviations in closing tests. Despite their apparent deviation, when tested with W4LT they will produce a normal BSV result, indicating an Abnormal Retinal Correspondence.

Esotropia

In Esotropic deviation (ET), the patient will experience uncyclical diplopia. When asked about the position of the lights, they will report that:

• They see 5 lights, 2 reds and 3 greens
• The lights are moved horizontally, visible side by side
• 2 red lights from the right eye are visible on the right side
• 3 green lights from the left eye are visible on the left side

This is recorded as: W4LT (D): 5 lights (Uncrossed Diplopia) ET

NB: Doctors will not be able to show which eyes are deviated based on these results alone. The results should be interpreted with other clinical findings to produce a final diagnosis.

Exotropia

In the Exotropic (XT) deviation, the patient will experience crossed diplopia.

When asked about the position of the lights, they will report that:

• They see 5 lights, 2 Red and 3 Green
• The lights are moved horizontally, and are shown side by side
• 2 Red Light from the Right Eye is on the left side
• The 3 green lights from the left eye are on the right side

This is recorded as: W4LT (D): 5 lights (Crossed Diplopia) XT

NB: Doctors will not be able to show which eyes are deviated based on these results alone. The results should be interpreted with other clinical findings to produce a final diagnosis.

Hypotropia/Hypertropia

In cases of vertical aberration, patients will report that:

• They see 5 Lights, 2 Reds, and 3 Greens
• The lights are moved vertically in relation to each other
• Green light (left eye) is above the red light (right eye)

Which is interpreted as: R HT or LHypoT

• Red Light (Right eye) is above the Green light (Left Eye)

Interpreted as: RHypoT or L H T

This is recorded as: W4LT (D): 5 lights (Vertical Diplopia)

Clinicians can connect the position of the lamp directly back to the aberration and the higher eye height (ie) of the higher lamp belonging to the higher eye, and the lower lamp belonging to the lower eye.

NB: If the lights are not located directly above each other, but also separated horizontally, it usually indicates mixed deviations where there is horizontal, as well as vertical present strabismus

Oppression

In the case of a real strabismus, it is not always expected that the patient will experience diplopia.

Suppression is indicated when the patient reports that:

• They only see 3 Green lights from the Left Eyes

Which is interpreted as R Suppression

• They only see 2 red lights from the right eye

Which is interpreted as L Suppression

• They see 2 red lights OR 3 green lights

All 5 lights are never present at the same time, but the patient switches between two responses. This result is interpreted as Alternating Suppression

These can be recorded as:

W4LT (D): 3 Lampu (R Supp.)

W4LT (D): 2 Lampu (L Supp.)

W4LT (D): 2 or 3 Lights (Alt Supp.)

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Advantages and disadvantages

Benefits

• Can be done quickly and easily in the clinic because the tests are easy to orient and red green glasses are placed over the eyes. There is no change of lens, as in Bagolini Striated Glasses Test which is another test of binocular function, making interpretation of results more complicated
• There are no large spectacle frames as in Bagolini's glasses test so the glasses are minimally obstructive to the patient's vision
• Bias correction may be worn under the glasses
• A good starting point when investigating the nature of diplopia is to find a real, intermittent, crossed, or non-intersecting diplopia
• This is less dissociative than the closing test
• Can be used to determine whether the patient will show single vision binoculars with corrective prism or head posture
• Relatively easy to record and interpret results

Disadvantages

• Subjective and dependent on patient responses
• The patient must have fusion and stereopsis to obtain accurate results
• This is a highly dissociative test so the response becomes less relevant to what the patient sees in their normal daily environment, since the environment will usually be different

1. A. The lamp must be turned off or dimmed to see the dots/lights

1. B. There are no common colors to merge

1. C. The dark filters in the eyewear are used and less like natural conditions and therefore less relevant to what the patient sees in their normal daily environment

• People with Red/Green blindness can not accurately perform the tests because the colors used in the red and green tests
• The test results are only useful in combination with testing and other results and not on their own
• If you do a double test, such as near and at a distance, patients (especially children) may remember their previous answers and only give the same answer from the last test, giving inaccurate results

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See also

• Eye examination
• Diplopia
• Strabismus

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References

• Eskridge, JB, Amos, JF, Bartlett, JD. Clinical procedure in Optometry. Lippincott Co. New York 1991.
• Carlson, NB, et al. Clinical Procedures for Ocular Examination. Second Ed. Mc Graw-Hill. New York 1996.
• Madge, SN, Kersey, JW, Hawker, MJ, Lamont, M. Clinical Techniques in Ophthalmology. Churchill Livingstone. London 2006.
• Ansons, A. & amp; Davis, H. (2008). Diagnosis and Management of Eye Motivation Disorders, Third Edition. [Wiley Online Library]. DOI: 10.1002/9780470698839
• Pratt-Johnson, J, Tillson, G. Strabismus and Amblyopia Management, Second Edition. Thieme. New York 2001.
• Gunter, K, Von Noorden, Emilio, C. Vision of Binocular Campos and Eye Motility (Theory and Management of Strabismus), 6th Edition (230)
• Anson, A, Davies, H. Diagnosis and Management of Eye Mobility Disorders, Fourth Edition. John Wilet & amp; Children. West Sussex, 2014.
• Pratt-Johnson, J, Tillson G, Strabismus and Amblyopia Management: A Practical Guide. Thieme Medical Publishers, 2006.
• Mitchell, P. R., Parksm M, M (2006) Sensory Tests and Treatment of Adaptation of Binocular Vision. Retrieved from http://www.eyecalcs.com/DWAN/pages/v1/v1c009.html
• American Academy of Ophthalmology (2014). 4-Dot Worth Test Retrieved http://one.aao.org/bcscsnippetdetail.aspx?id=8200e4a2-f7ee-47f4-b8b7-985b30b52f67

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External links

• W4LT- A Video Demonstration

Source of the article : Wikipedia