Measuring eye refraction

A device for vision prescription measurement, the device comprising:

• a housing;
• an image acquisition unit disposed in the housing and configured to automatically measure a distance between a patient and the housing;
• a display on at least part of an external surface of the housing, the display being configured to present one or more visual targets sized and shaped to represent perfect vision, the visual targets including Vernier targets;
• a processor disposed in the housing, the processor configured to determine accurate sizes and shapes of the one or more visual targets based on the measured distance;
• wherein the display is configured to instruct the patient to indicate whether the patient can accurately read the visual targets and, if not, to move closer to the housing until the patient can accurately read the visual targets;
• wherein the image acquisition unit is configured to automatically measure the distance between the patient and the housing at least one additional time at a final distance at which distance the patient can accurately read the visual targets;
• and
• wherein the processor is configured to calculate a vision prescription for the patient based on the visual targets and the final distance between the patient and the mobile device, and the display is configured to display the calculated vision prescription.

A method of vision prescription measurement, the method comprising:

• measuring, with a mobile device, a distance between a patient and the mobile device;
• presenting, on a display of the mobile device, one or more visual targets sized and shaped to represent perfect vision;
• determining, using the mobile device, accurate sizes and shapes of the one or more visual targets based on the measured distance;
• measuring, using the mobile device, the distance between the patient and the mobile device at a final distance corresponding to the patient accurately reading the visual targets;
• determining, using the mobile device, a vision prescription for the patient based on the visual targets and the final distance.