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 mm 2 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 mm 2 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. Electronic supplementary material The online version of this article (10.1007/s40123-019-0175-9) contains supplementary material, which is available to authorized users.

Standard automated perimetry using size III and size V stimuli in advanced stage glaucoma: an observational cross-sectional comparative study

“…3 Gardiner et al confirmed size V resulted in higher sensitivity at the same location, providing more reliable and less variable estimates of sensitivity in damaged visual fields. Their higher sensitivity was on average 5.6 dB-similar to our average of 6 dB and to the average of 6 and 7.6 dB reported by Morgan et al 22 and Choplin et al, 8 respectively.…”

“…Further, and not surprising, we found longer test durations for size V compared with size III and in keeping with other studies. 22 This reflects the greater visual response to the larger size V target. Thus, the more targets than can be detected and responded to, the longer the test time will be.…”

“…One recent study sought to gather patient perspectives and reliability based on clinical grounds while comparing size III and V stimulus sizes using a 24-2 test programme. 22 They concluded that adjustment of testing to use of size V increased their patient cooperation and was a valid option when attempting to gather more reliable perimetry results. From our clinical perspective, we found the results using size V to provide more visual field data to help inform clinical decision making and a grounding towards future disease monitoring.…”

“…This indicates less visual field loss for size V stimulus compared with the indication of absolute defects for size III stimulus when mean sensitivity values are low (<10 dB) and is indicative of the relationship between stimulus size and luminance. 22 Many perimeter parameters are such that at maximum luminance, the size III target has a calibrated range of 2-44 dB and the size V target has a range of 10-54 dB (10 dB difference). As expected, the larger stimulus size increases sensitivity and this is particularly so at greater eccentricities.…”

Utility of Central 10 Degrees Visual Field Test With Size V Stimulus in End-Stage Glaucoma

“…Under such conditions, changing the target from a generally used size III (0.43 degrees diameter; 4 mm 2 area) stimulus to a larger size V (1.72 degrees diameter; 64 mm 2 area) stimulus may be helpful. Despite several studies have investigated visual field test results using the size V stimulus in glaucoma, [5][6][7][8][9][10][11] little is known about the utility of the central 10 degrees visual field test with the size V stimulus in end-stage glaucoma. 3 For instance, a study compared central 10 degrees visual field test results using the size V stimulus with central 30 degrees visual field test results using the size III and V stimuli.…”