Worth 4 dot test

Worth 4 Dot Test is a clinical examination used primarily by ophthalmologists, optometrists, and other eye care professionals to assess a patient's degree of binocular vision and the ability to perceive depth. The test is named after its inventor, Claud Worth, a British ophthalmologist who introduced it in the early 20th century. It is a simple, yet effective diagnostic tool that helps in identifying anomalies in binocular vision, such as strabismus (misalignment of the eyes), amblyopia (lazy eye), and suppression of vision in one eye.

Procedure

The Worth 4 Dot Test consists of a handheld flashlight that projects four dots in a diamond shape: three green dots arranged vertically and one red dot at the top. The patient is asked to wear red-green glasses, with the red filter over the right eye and the green filter over the left eye. In a dimly lit room, the patient views the dots from a specified distance, usually at 6 meters (20 feet) for distance vision and at 33 centimeters (13 inches) for near vision.

Interpretation of Results

The perception of the dots varies depending on the patient's binocular visual function:

• Seeing four dots indicates normal binocular vision, with both eyes working together properly.
• Seeing two red dots suggests suppression of the vision in the left eye.
• Seeing three green dots indicates suppression of the vision in the right eye.
• Seeing five dots (two red and three green) suggests double vision (diplopia) or a lack of fusion between the eyes.

Clinical Significance

The Worth 4 Dot Test is a valuable component of a comprehensive eye examination, especially in patients complaining of visual discomfort, headaches, or those with a history of strabismus or amblyopia. It helps in determining the presence and extent of suppression and binocular vision anomalies, which are crucial for planning treatment strategies such as vision therapy, corrective lenses, or surgery.

Limitations

While the Worth 4 Dot Test provides useful information about binocular vision, it has its limitations. It does not quantify the degree of binocular function or depth perception. Moreover, the test's reliance on patient response can be subjective, and results may vary based on the patient's understanding and cooperation. Therefore, it is often used in conjunction with other diagnostic tools for a more comprehensive assessment of binocular vision.

See Also

• Stereopsis
• Vision therapy
• Strabismus surgery
• Amblyopia