Expediency of the Automated Perimetry Using the Goldmann V Stimulus Size in Visually Impaired Patients with Glaucoma

Abstract

Introduction: White-on-white standard automated perimetry (AP) uses a white round stimulus with 0.43° diameter and 4.0 mm² area (Goldmann size III). Patients with low vision have difficulty seeing such a small stimulus and are often tested with perimetry using the size V stimulus with 1.72° diameter and 64 mm² area. We undertook an observational case-control study to compare the performance of patients on AP using two differently sized stimuli.

Methods: Patients with glaucoma and visual acuity worse than 20/100 underwent AP using the standard size III stimulus Swedish Interactive Threshold Algorithm (SITA) standard test and size V stimulus full threshold test. All patients were familiar with the procedure, having done the test at least twice previously. Another group of glaucoma patients with visual acuity better than 20/40 served as controls. The main outcome measures included test time, mean retinal sensitivity (MRS), foveal sensitivity (FS), fixation loss (FL), false positive (FP), false negative (FN), and the patient's subjective preference.

Results: Fifty patients were included in the study. Most preferred the size V stimulus target size test. For glaucoma patients, test time was shorter with size III; MRS and FS were higher with size V; FL, FP, and FN did not differ between the tests.

Conclusion: AP with stimulus size V may be a good alternative to standard size III in selected visually debilitated patients who report difficulty undergoing a standard SITA 24-2 test.

Keywords: Automated perimetry; Glaucoma; Psychophysics; Stimulus size; Visual field.

Fig. 1

a Printout of the SITA 24-2 test result using the regular stimulus size III. b Printout of the full threshold FASTPAC with stimulus size V

Fig. 1

a Printout of the SITA 24-2 test result using the regular stimulus size III. b Printout of the full threshold FASTPAC with stimulus size V