The Worth Four Dot Test is used to determine the presence of suppression or diplopia. It involves having the patient view four lights (one red, two green, one white) through red-green lenses. The number and configuration of lights seen indicates the type of strabismus or binocular vision status. It is an inexpensive and easy to administer test, but relies on subjective patient responses. Some studies have found it can provide reliable results even in patients with red-green color vision defects.

1. WORTH FOUR DOT TEST
KAUSTAV GOGOI
B. OPTOM 4TH YEAR, RCOJ

2. LAYOUTS
 INTRODUCTION
 PRINCIPLE
 USES
 METHODS
 REQUIREMENTS
 PROCEDURE
 INTERPRETATION
 ADVANTAGES & DISADVANTAGES
 REFERRENCES

3. INTRODUCTION
 Also called Worth Four Light Test (W4LT)
 Consisting of four lights arranged in a diamond shape with a red light at the top, two
green lights at the left and right sides and a white light at the bottom

4. PRINCIPLE
 Based on Anaglyphic method
 Utilizes different colors,such as RED and GREEN,while presenting the two images to
the eyes.
 When the images are viewed,the visual cortex of the brain fuses the images to
produce one integrated stereoscopic image.

5. WHY IT IS USED -
 To determine suppression
 To determine the nature and type of diplopia
 To identify vertical and horizontal strabismus

6. METHODS
 There are two ways to perform –
1. Distance worth four dot test: At a 6-meter distance from the patient, there are two
fixed targets that can be presented on a screen or an illuminated box
2. Near worth four dot test: Target is fixed at a distance of 33cm from the patient which
consists of a flashlight to alter the projection angle

7. REQUIREMENTS
 Trial frame with a red and green filter or Armstrong Goggle
 Illuminated worth four dot box or flashlight

8. SETUP
 Describe to the patient the test and procedure
 The patient must put on green-and-red glasses (Armstrong glasses). Red light will be visible to the eye
with the red filter on its front (often the right eye), and green light will be visible to the eye with the
green filter on its front (typically the left eye). Before putting on the red and green spectacles, make
sure the patient can’t see the torch.
1. To test at distance (6m) : Make that the patient is using the glasses or contact lenses that are prescribed.
2. To test at near (33cm) : Hold the Worth 4-dot torch or flashlight such that the patient is reading it while
slanting his or her head slightly downward. Make that the patient is wearing the correct refractive
correction for near-distance testing if they have presbyopia. Usually, a red light is at the top and a white
light is at the bottom of the torch.
3. Turn on the Worth 4-dot instrument by keeping the room lights on

9. PROCEDURE
 Cover the patient’s left eye and ask, ‘How many lights do you see?’
 Now cover the right eye and ask, ‘How many lights do you see?’
 Now with the both eyes open ask the patient, ‘How many lights do you see?’
 Are all lights in line or some higher than the others?
 Do all the lights show up at one time,or are they flashing on and off ?

10. INTERPRETATIONS
4 DOTS – 1 RED, 2 GREEN, 1 ORANGE
NORMAL BINOCULAR VISION

11. 3 GREEN DOTS
RIGHT EYE SUPPRESSION

12. 2 RED DOTS
LEFT EYE SUPPRESSION

13. 2 RED DOTS & 3 GREEN DOTS alternatively
ALTERNATE SUPPRESSION

14. 5 DOTS – 2 RED IN RIGHT EYE , 3 GREEN IN THE LEFT EYE
UNCROSSED DIPLOPIA

15. 5 DOTS – 3 GREEN IN THE RIGHT EYE & 2 RED IN THE LEFT EYE
CROSSED DIPLOPIA

16. 5 DOTS – 2 RED ON THE UPPER SIDE &3 GREEN ON THE LOWER
SIDE
VERTICAL DIPLOPIA with RIGHT HYPOTROPIA or LEFT
HYPERTROPIA

17. 5 DOTS – 3 GREEN ON THE UPPER SIDE & 2 RED ON THE LOWER SIDE
VERTICAL DIPLOPIA with LEFT HYPOTROPIA & RIGHT
HYPERTROPIA

18. ADVANTAGES
 Widely available, cheap, practical, and easy to use
 Results were quite simple to record
 Refractive correction can be worn under the goggles

19. DISADVANTAGES
 Dependent on the responses of the patients and subjective in character
 If the test is administered twice,for instance,close-up and far-away,the patient-
particularly kids-might recall their previous response and provide the same response
from the previous test,leading to incorrect results

20. RELIABILITY IN RED-GREEN COLOR VISION DEFECT
 A retrospective study was done by Eunoo Bak et al.Optom Vis Sci in May 2017
on Validity of the Worth 4 Dot Test in Patients with Red-Green Color
Vision Defect where they found that congenital red-green color vision defect
patients of different types and variable degree of binocularity could successfully
perform the W4DT and they showed reliable results

21. REFERRENCES
 A K KHURANA,Page No-132,Theory and Practice of Squint and Orthoptics
 BRUCE EVANS&SANDIP DOSHI,Page No-60,Binocular Vision and Orthoptics
 Mitchell Scheiman-Bruce Wick Page No-3t,4,15-16,44
 Eunoo Bak, Hee Kyung Yang, Jeong-Min Hwang. Validity of the Worth 4 Dot Test in Patients with
Red-Green Color Vision Defect, Optom Vis Sci. 2017 May;94(5):626-629
• https://en.wikipedia.org/wiki/Worth_4_dot_test
• https://eyewiki.aao.org/Worth_4_dot