BACKGROUND cognitive test scores and visual acuity are strongly associated in older people. This may be due to poor vision limiting performance on cognitive tasks specifically requiring vision, or an association between visual and neurodegenerative disorders. OBJECTIVE to explore, using data from the Newcastle 85+ cohort study, the impact of sight impairment (SI) on Mini-Mental State Examination (MMSE) scores and whether reduced scores among SI participants are limited to tasks requiring vision. RESULTS of 839 participants aged 85 years, 44 (5.2%) were registered SI. Median (inter-quartile range) sMMSE scores were 25 (22-29) for SI and 28 (25-29) for non-SI participants (P=0.006). SI participants had lower subscale scores on tasks requiring vision (P<0.001 for each) but also for some subscale scores not obviously requiring vision: orientation (P=0.018) and repetition (P=0.030). Excluding visual items, there was no significant difference in MMSE scores between those with/without SI. CONCLUSION SI may be an obstacle to older people completing cognitive assessments including tasks requiring vision. People with SI also scored lower on some tasks not obviously requiring vision. An association between cognitive impairment and SI may exist beyond simply being unable to see the test material in cognitive tests.