Purpose: Executive function and visual search are linked to a number of activities of daily living including driving and mobility. Using a computerised version of the Trail Making Test B (TMT-B), we compared the executive function and visual search ability of older adults with glaucoma to age-similar controls and identified which visual function tests best predict TMT-B performance. Novel low-contrast and shifting-target variations of the test were incorporated to explore the effects of different levels of test complexity. Methods: Thirty-one older adults with mild to moderate glaucoma (mean age = 71.2 years [SD 6.9]; better-eye mean deviation [MD]: median = −1.9 dB [IQR = −1.2 to 0.4], worse-eye MD: median = −11.1 dB [IQR = −14.0 to −7.7]) and 24 age-similar controls (mean age = 71.9 years [SD 6.6]) with normal vision participated. The groups were matched in age, sex, and cognitive status (mini-mental state examination [MMSE]). Participants underwent measurements of visual acuity, contrast sensitivity (CS), visual fields, and visual processing speeds using the useful field-of-view (UFoV). Participants then completed four variations of a computerised TMT-B test, with different levels of complexity based on target contrast (high/low-contrast) and shifts in target position (fixed/shifting locations). Linear mixed-effect models were used to explore the effects of group, target contrast and shift on TMT-B completion time. Results: The glaucoma group took 17.3s longer than controls to complete the TMT-B (P = 0.028). All participants took 6.5s longer to complete the low- compared to the high-contrast tests (P = 0.012), and 10.6s longer for the shifting TMT-B compared to the fixed version (P < 0.001). There was no interaction effect between group, contrast, or target shift on completion time. Across all tests and participant groups, longer completion time was associated with slower UFoV processing speeds (divided attention: P = 0.003; selective attention: P = 0.006). Poorer CS was associated with longer completion times for the low (P = 0.007), but not the high-contrast tests. Conclusions: Our findings suggest that older adults with mild to moderate glaucoma have poorer visual search ability and executive function relative to controls. However, decreasing target contrast or shifting target position did not exacerbate the effects of glaucomatous visual impairment on performance. The UFoV was a strong predictor of TMT-B performance.