Purpose: To assess the impact of medPlan®, a medication reminder mobile application in glaucoma patients in Benin City, Nigeria.Methods: In a randomized control trial with 2 months follow-up period, 200 patients receiving drug therapy for glaucoma were  randomized into either into a control or study group. The study group comprised participants who made use of a medication reminder mobile application, medPlan®, while the control group consisted of those patients who did not use the application. Adherence to medication was measured for all the patients in both groups. Data was collected using a carefully designed questionnaire and statistically analyzed.Results: This study recorded 100 % response rate from the participants. In the study group, 56 % were very adherent while 18 % were moderately adherent, and 26 % were non-adherent respondents as against 45 % very adherent, 13 % moderately adherent and 42 % non-adherent respondents from the control group. In addition, 78 % of those in the study group agreed that there was improvement in their medication adherence since they started using the medication reminder application. This showed a significant positive impact of the medication reminder application (p = 0.0110) on adherence to medication.Conclusion: Medication adherence was improved in glaucoma patients who used medPlan®, a smartphone medication reminder application. This study lays a foundation for further research on medication reminder mobile applications. Keywords: Glaucoma, Smartphone, Medication adherence, Impact, Medication reminder, medPlan®