NVT Welcomes Worth 4 Dot!

Fusion, diplopia, or suppression - which one is happening to your patients? When, and how can you tell?

For over a century, the Worth 4 Dot test has been helping clinicians to quickly determine which adaptation strategy their patients are using at any given moment. The test was developed by British ophthalmologist Claud Worth, one of the pioneers of modern binocular vision and amblyopia treatment. He was an early advocate of treating binocular vision disorders by restoring binocular function rather than simply aligning the eyes cosmetically. This philosophy would go on to inform the entire underlying ethos in the fields of behavioural optometry and vision therapy.

This simple and elegant test used four lights arranged in a diamond pattern: one red, two green and one white. The patient would view the lights through red-green glasses, causing each eye to see a different subset of the targets. Depending on how many lights the patient reports seeing, the clinician can quickly determine whether the patient is successfully using both eyes together (binocular fusion), if their brain is ignoring the input from one eye (suppression), seeing two disparate images simultaneously (diplopia), or if they are alternating between these states.

Patient View 0Δ	Interpretation
	Normal fusion: the patient reports four dots in a diamond pattern with no alternation in color.
	Left suppression: the patient reports two red dots.
	Right suppression: the patient reports three blue dots.
	Uncrossed diplopia (Eso): the patient reports five dots, with red appearing to the right of blue or merely offset from center when the diplopia is mild.
	Crossed diplopia (Exo): the patient reports five dots, with red appearing to the left of blue or merely offset from center when the diplopia is mild.
	Vertical diplopia (OD Hyper, OS Hypo): the patient reports five dots, with red appearing below blue or merely vertically offset from center when the diplopia is mild.
	Vertical diplopia (OD Hypo, OS Hyper): the patient reports five dots, with red appearing above blue or merely vertically offset from center when the diplopia is mild.
	Alternating suppression: the patient reports seeing three blue dots, then two red dots, then three blue dots, etc. The pattern alternates, and they do not see (or rarely see) the magenta dot. This may also be present with diplopia.

Several different variations of this test have been created over the years - from wall-mounted light boxes to a handheld flashlight with the four dot targets on a filter. NeuroVisual Trainer now brings this classic binocular vision assessment into the digital age.

Like the rest of NVT's catalogue of interactive activities, our new Worth 4 Dot works with any anaglyph glasses, and like NVT's Vectographs, the vergence demands can be adjusted on the fly, in any direction - BI, BO, and vertical. You can also adjust the amount of prism that is simulated with each step, as well as the overall size of the dots.

Learn more about the nuances of a patient's binocular vision by configuring the Worth 4 Dot test for different custom working distances, to help determine if a patient is, for example, fusing at near, then suppressing beyond a certain distance.

Isolate and adjust the brightness for each eye, to help confirm your suspicions!

In addition to the standalone screening tool, nested in the Testing category, you can also directly integrate Worth 4 Dot into some of NVT's Interactive Exercises, like Exploratory Vectographs, Exploratory Flat Vergence, Exploratory Flat Jump Duction, as well as all Multiple Choice Stereo Vergence variants. This allows clinicians to monitor their patients' binocular status throughout a therapy session, rather than just an isolated moment in time. Then it becomes less of a test and more of a real-time binocular status monitor, providing valuable insight as to exactly when suppression, fusion, or diplopia occurs during functional activities.

That's a pretty powerful evolution of that simple little test that Claud Worth first came up with over 100 years ago.

Give it a try and let us know what you think!