Objective: To identify and assess strategies for evaluating the impact of mobile eye health units on health outcomes. Design: Systematic literature review. Setting: Worldwide. Participants: Peer-reviewed journal articles that included the use of a mobile eye health unit. Main outcome measure(s): Journal articles were included if outcome measures reflected an assessment of the impact of a mobile eye health unit on health outcomes. Results: Six studies were identified with mobile services offering diabetic retinopathy screening (three studies), optometric services (two studies) and orthoptic services (one study). Conclusion: This review identified and assessed strategies in existing literature used to evaluate the impact of mobile eye health units on health outcomes. Studies included in this review used patient outcomes (i.e. disease detection, vision impairment, treatment compliance) and/or service delivery outcomes (i.e. cost per attendance, hospital transport use, inappropriate referrals, time from diabetic retinopathy photography to treatment) to evaluate the impact of mobile eye health units. Limitations include difficulty proving causation of specific outcome measures and the overall shortage of impact evaluation studies. Variation in geographical location, service population and nature of eye care providers limits broad application.