During the FDT, what should the patient focus on?

The correct choice emphasizes the importance of the patient's focus during the Frequency Doubling Technology (FDT) test, which is used to assess the visual field. When the patient focuses on the black dot in the middle of the screen, it ensures that their attention is directed to a central point, allowing the test to accurately measure their peripheral vision.

This focus is crucial because the FDT evaluates the ability to detect visual stimuli in the peripheral visual field while keeping the central vision stable. By concentrating on the black dot, the patient is less likely to be distracted by other visual elements, such as the colored circles or any other patterns on the screen, which could lead to inaccurate results.

In the context of this test, the role of the black dot is to serve as a fixation point; it helps maintain stability in eye movement, thus providing a reliable measurement of the visual field. This process ensures that the evaluation of vision is consistent and that any potential issues can be identified effectively.