Eye-tracking is a technique for monitoring and analyzing the movement of a person's eyes as they interact with stimuli such as images, videos, or user interfaces. This method uses specialized hardware and software to precisely track the direction and duration of eye fixations and movements.

In usability studies, the eye-tracking method enables researchers to understand how users interact visually with user interfaces, websites, or products by revealing patterns of attention, areas of interest, and navigation strategies. By capturing and analyzing eye movement data, researchers can gain valuable insights into user behavior, attention processes, and cognitive workload, which ultimately supports the design and optimization of user interfaces and digital products.

Formative evaluation in the field of usability of medical devices is about assessing the user-friendliness of a product during the development phases. The aim is to identify usability problems at an early stage so that iterative improvements can be made to the design. This process usually involves conducting usability tests with potential representative users. The feedback can be used to gain insights that can then be used to improve the design.

Summative evaluation, on the other hand, is carried out as soon as the respective product is nearing completion or has already been completed. The focus of this evaluation is the overall assessment of the user-friendliness and safety of the product based on predefined criteria or standards. The summative evaluation often includes formal testing, including a usability test and validation studies. This ensures that the product meets the legal requirements and the needs of the users