Abstract:

The adscription of the Optometry degree to the Faculty of Physics in the University of Valencia has given it a “basic sciences” bias, that many students perceive as disconnected from their future professional practice. Basic vision science and visual perception subjects, with their use of mathematical models and computing tools in the laboratory are viewed with particular hostility. We have found that encouraging the students to design clinical vision tests is a good way to show the relevance and applicability of these basic vision science disciplines to their future work as optometrists.

This is what we do in the lab sessions of the subject "Psychophysical Methods for Dectection and Follow up of Visual Pathologies" (PMD). The students must go through all the steps necessary to design and validate a contrast sensitivity test (CST), which is common in optometric practice. The students realize that designing such a test implies a series of decisions based in the knowledge of how the visual system works. They must analyze the problem, apply knowledge and skills acquired in different subjects, do bibliographical searches, work in group and critically analyze their results. The experience has been functioning for two academic years, with satisfactory results.

The lab groups usually involve 18 students or less. The task is carried out during 3 lab sessions, of 4 hours each. At the beginning of the first session, the teacher explains the task.

The work is organized in three basic stages:
a) The design stage. The students must make reasoned decisions on stimulus characteristics (spatial profile, color, contrast) and the psychophysical method to be used, and implement the test.
b) Testing stage. A reduced normative database must be obtained, and the repeatability and agreement with a reference technique, as well as the diagnostic capabilities of the test analyzed.
c) Analysis stage: The students must assess how well does the test work and decide if any of the decisions taken during the design stage should be revised.

The students organize themselves, assign the different tasks to different groups and discuss the different steps to be taken. Without collaborative work, it is impossible to generate the large number of stimuli nor to obtain the normative database. The technical difficulties (how to generate physically the stimuli, for instance) are minimized by the use of specific stimulus generating software (1,2). The teacher acts as a technical consultor, helping with the implementation of the psychophysical procedure if programming skills are required and asking the necessary questions to ensure the group does not miss fundamental issues.

The result is not just the immediate outcome of the exercise, that is, whether a functional CST has or has not been designed. In PMD, students are graded by their design, implementation and testing of a clinical test. This work, carried out in groups of four persons, requires the skills and knowledge practiced in the lab exercise. We have been also happy to ascertain that this experience has encouraged at least some students to begin research work.

References:
[1] MJ Luque, D de Fez, MC García-Domene y V Moncho. Tools for generating customized visual stimuli in visual perception labs using computer controlled monitors. Proc. ICERI 2013 Conf. 2013, 6200-6207.
[2] J Malo and MJ Luque. "COLORLAB: a color processing toolbox for Matlab", http://www.uv.es/vista/vistavalencia/software.html

Keywords:

Clinical psychophysics, problem-based learning.