The diplopia field test is currently valid not so much in the diagnosis as in the monitoring of oculomotor paralysis and diplopia. It enables the field of gaze to be accurately detailed and is therefore useful for determining the areas of fusion and diplopia in the different gaze positions. In reality, what is studied is whether in different gaze positions there is single vision, binocular vision or diplopia, so that we can discover where these areas begin and end and therefore their location and extent.

The study of the diplopia field is not a diagnostic test in the sense of detecting the pathological muscle or muscles, but it allows its quantification and evolution, being relatively easy to perform.

Under normal conditions, the binocular field of gaze has the shape of an ellipse covering about 140º on the horizontal axis and 125º on the vertical axis. There is an area common to both eyes, central, with an extension of about 120º and in the shape of a diamond. On either side of this area is a crescent or temporal crescent corresponding to the area of monocular vision.

As indicated in the introduction, the instrument used to study the diplopia field has usually been the Goldman campimeter. Less frequently, the Tubingen campimeter and the arc perimeter were used. The Hess and Lancaster screens have not been used as they do not have the necessary extension to explore the extremes of the different positions. The Goldman campimeter allows theoretical displacements of up to 90° in the temporal field and 60° in the nasal field, which is beyond the range of the Hess and Lancaster screens.

There is currently no possibility to purchase a Goldman campimeter.

The current systems implemented use a radial scanning algorithm, with the number of radii scanned being variable. This method makes it impossible to map the diplopia field with any accuracy. In short, the diplopia field can be represented as a surface to be delimited, so trying to delimit it by scanning radii is an impossibility. Therefore, a new scanning algorithm has been designed which consists of delimiting the diplopia field by measuring its extension in each of the 23 horizontal lines into which the area it would theoretically occupy has been divided. In this way we can know precisely what the left and right limits are.

This is why the need for a system that allows the detailed mapping of the diplopia field, the areas of fusion and the areas of monocular vision has been assessed. The aim is to help the doctor in a simple, efficient and reproducible way. Thus, to fulfil these purposes, the following requirements must be met:

1. Simplicity of configuration and use.
2. Efficiently usable by ophthalmologists, neurologists and other personnel who need it.
3. Possibility of personalised configuration of the scanning screen and the size, shape and colour of the core.
4. Goldman's standard sizes of the core, with the possibility of adjusting them to the scanning distance and size of the screen.
5. Scanning algorithm consisting of scanning 23 horizontal lines to know the left and right boundaries.
6. Possibility of studying the field of gaze, the binocular field of vision and the field of diplopia, or any combination.
7. Possibility of changing the speed at which the token moves, both in angular velocity, degrees/second, and in millimetres/second.
8. Ability to change the direction of movement of the token.
9. Possibility to move the tell-tale automatically or manually.
10. Possibility of scanning in such a way as to cover the entire field of vision of the gaze.
11. System for recording all scanning parameters: distance, size and colour of the screen, size of the baton used, its shape and colour, type of scanning performed, responses made, variations in the response of each axis.
12. A system for printing out the tests carried out, including both graphical and numerical data.
13. System for comparing the tests carried out in such a way that the evolution of a point or group of points can be followed through the different scans.
14. Possibility to perform the test in an automated or completely manual way.
15. Possibility to perform and archive all test data.