SITA standard testing with Humphrey visual field analyzer versus full threshold testing with frequency doubling perimetry: a comparison of patient preference and perception

Abstract

Purpose: To compare patient preference for Swedish Interactive Threshold Algorithm (SITA) standard 24-2 protocol in Humphrey visual field analyzer (HVF) and full threshold N-30 protocol in frequency doubling perimetry (FDP) by primarily evaluating their perception about the test procedure and test targets along with surveying the factors that influence the patient concentration during perimetry and elements that determine the level of perimetry task difficulty. Methods: This study enrolled a subset of subjects from the Chennai Glaucoma Study. Each subject underwent a comprehensive ophthalmic examination after which they were randomly allocated to perform HVF and FDP with a 30-minute interval between the two procedures. SITA standard 24-2 protocol in HVF and full threshold N-30 protocol in FDP were used. This was followed by the administration of a questionnaire that mainly assessed the components such as (a) the patient preference for test procedure and test targets, (b) the factors influencing the patient concentration during perimetry performance, and (c) the impression about the level of perimetry task difficulty. The patient responses from the survey for each of the subcategories were obtained and analyzed using Chi-square test. Results: A total of 42 subjects with a mean age of 59.7 (SD 9.7) years were included, among which 18 (42.86%) were male and 24 (57.14%) were female. Thirty-two (76.19%) subjects felt both FDP and HVF were easy to perform, eight subjects (19.05%) felt that both perimetry techniques were difficult to perform, and two subjects (4.76%) found FDP procedure was easier than HVF, whereas the distribution was not statistically significant (Chi-square, p = 0.7). Pressing the button as a response to peripheral stimulus perception and inability to maintain steady central fixation for prolonged duration were the most commonly reported factors that influenced the level of difficulty of the perimetry tasks. A dark room ambience set for performing HVF was preferred by 32 (76.20%) subjects. Conclusion: There was no significant difference in the patient preference for test procedure and peripheral test targets. A black central fixation as in FDP and dark room ambience set for HVF were preferred.