Objectives: To determine the agreement and correlation of visual acuity between Rapid Eye Screening Test (REST) app and Early Treatment Diabetic Retinopathy Study (ETDRS) tumbling ‘E’ chart.

Methods: A visual acuity tool was designed for Android and iOS users based on ETDRS. A pilot study was conducted involving 101 subjects. Visual acuity of each subject was tested using ETDRS chart and crossover to REST at 3 meters or vice versa.

Results: Mean visual acuity using ETDRS was 0.086 ± 0.194 for right eye (RE) and 0.085 ± 0.196 for left eye (LE) while REST measurement was 0.091 ± 0.182 for RE and 0.098 ± 0.203 for LE. There was significant and strong direct correlation between visual acuity using ETDRS and REST in both eyes (RE: r = 0.829; p < 0.001, LE: r = 0.871; p < 0.001). The 95% limits of agreement between the two charts was ±0.11 LogMAR for right eye and ±0.10 LogMAR for left eye. Time taken for REST was significantly shorter than ETDRS (p < 0.001).

Conclusion: REST is accurate and time-saving, thus potentially ideal for mass screening in remote area.

Background: Persons who inject drugs (PWID) are at high risk for hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection, particularly in Tijuana, Baja California, Mexico, where HCV prevalence among PWID is above 95%. PWID also demonstrate low access and use of health services. mHealth intervention tools may prove effective for reducing disease risk and increasing access to health services for PWID. However, knowledge of cell phone access within this population is needed before designing such interventions.

Methods: We aimed to determine the prevalence and correlates of cell phone access among PWID enrolled in the ‘El Cuete’ cohort study in Tijuana. Participants were asked for detailed contact information at baseline—including a cell phone number if available—to facilitate retention. Interviews obtained socio-demographic data, health information, and lifetime/recent drug and sexual risk behaviors. Logistic regression was used to assess factors independently associated with providing a cell phone number.

Results: Of 735 participants enrolled, 16% of participants had access to a cell phone at baseline. Mean age was 37 years old, ranging from 18–63. Sixty two percent of participants were male, 96% were Hispanic, and 27% reported recent homelessness. Higher education and a monthly income≥2500 pesos were associated with higher odds of cell phone access. Inversely, homelessness, daily injection drug use, and older age were associated with lower odds of cell phone access.

Conclusions: Cell phone access among PWID in Tijuana is low and should be considered in the design of mHealth interventions targeting this population.