The perfect visual field test: does it exist?

Abstract

The role of standard automated perimetry in glaucoma monitoring is irrefutable. White on white standard automated perimetry has been used in clinical practice since 1970 with the Octopus Perimeter. 1 Subsequently, Andres Heigl and his colleagues were instrumental in the development of what is arguably the most used perimetry test and analysis method in current clinical practice and research, the Humphrey Field Analyser. 2 It has undergone many improvements since its inception. Measures were developed to improve the accuracy, make the tests easier to perform, enhance efficiency, and establish a robust system to enhance the reliability. In this current issue of Malaysian Journal of Ophthalmology, we have two articles which have highlighted the issue of enhancing the reliability of Humphrey visual field (HVF) results. In the first article, Mahayana et al. investigated the reliability parameters after three repeated HVF tests in the same patient spread over several days. They concluded that it required three perimetry examinations for the learning effect to diminish. Interestingly, while factors such as duration of test, fixation loss, and false-positive rates improved with each subsequent test, there was no sta-tistically significant change in global indices. This indicates the robustness of the algorithm for glaucoma detection irrespective of the learning effect. In other words, the defects in pathological field loss are not possible to learn. The second article investigated the effect of instructional videos on patients doing HVF for the first time. This is an important article which highlights how the artefact of learning effect can be minimised in perimetry through the use of demon-stration videos. It is especially pertinent in patients undergoing perimetry for the first time. The findings of improved reliability parameters after watching the instructional videos were particularly evident in patients from lower educational levels. Performing a HVF test is tedious at best for a patient.