Individuals being referred from screening events randomized to "no intervention" received the standard approach to offering free follow-up examinations (patient education, standard counseling, appointment information packet, reminder phone calls).

In addition to receiving the standard approach above, individuals being referred from screening events randomized to "Voucher Without Value Information" received a personal voucher.

In addition to receiving the standard approach above, individuals being referred from screening events randomized to "Voucher With Value Information" received a personal voucher, which differed from the voucher in the second arm since it included a statement of value.

Patients being referred for follow-up received standard materials, counseling, and reminders as in the 'no information' group and were provided with a physical voucher they were told is redeemable for free follow-up appointment at Johns Hopkins Hospital. The voucher included the patient's name, the screener's name, and an expiration date 90 days from the date of screening.

These participants were told: "I am going to give you this voucher for a completely free appointment and a free pair of glasses if you need them. So, with this voucher, both the exam and the glasses will be completely free."

The primary endpoint was attending a follow-up appointment, either on the initially scheduled or on a rescheduled date within 90 days of the date of screening. Individuals who did not meet this endpoint either stated that they were not interested in follow-up at the screening event itself, cancelled or did not show for their appointments on 3 occasions, stated that they were not interested in follow-up when study staff attempted to reschedule, or did not show for an appointment and could not be reached for rescheduling after 3 attempts.

Binary indicator for completion of the initially scheduled appointment.