Systems and methods for displaying objects on a screen at a desired visual angle

1. A system in communication with a first device capable of receiving input from a camera attached to the first device, and a second device capable of displaying output, the system configured to:

pair a first device to a second device through an identifier;

receive, from the first device, data relating to characteristics of a camera operably coupled to the first device and relating to characteristics of an image obtained by the camera of a display device operably coupled to the second device;

determine a screen pixel length of the display device; and

transmit instructions to the second device to output for display at the display device an object at a desired visual angle in response to the data received from the second device and the screen pixel length, while the first device is positioned at an arbitrary distance from the screen.

2. The system of claim 1 , further configured to receive from the second device an indication of the screen pixel length of the display device.

3. The system of claim 1 , wherein the data relating to characteristics of the camera comprise a focal length and a sensor size of the camera.

4. The system of claim 3 , wherein the data relating to characteristics of the image obtained by the camera of the display device comprise a camera pixel height of the image and a camera pixel height of the display device within the image.

5. The system of claim 4 , wherein the system is further configured to determine a visual angle of the display device prior to transmitting the instructions to the second device to output for display at the display device the object.

6. The system of claim 1 , wherein the object displayed at the display device is an optotype, and wherein the system is further configured to receive an indication from one of: the first device or the second device of user input from a test subject proximate to the first device in response to the displayed optotype.

7. The system of claim 6 , wherein the system is further configured to determine, based at least in part on the indication of the user input provided by the test subject in response to the optotype displayed at the display device, at least one of: a diagnosis for the test subject, a lens prescription for the test subject, or information to be provided to a doctor to determine a diagnosis or a lens prescription for the test subject.

8. A method for conducting a vision test, comprising:

pairing a first device to a second device through an identifier;

receiving, by a system from the first device, data relating to characteristics of a camera operably coupled to the first device and relating to characteristics of an image obtained by the camera of a display device operably coupled to the second device;

determining, by the system, a screen pixel length of the display device; and

transmitting, by the system, instructions to the second device to output for display at the display device an object at a desired visual angle in response to the data received from the second device and the screen pixel length, while the first device is positioned at an arbitrary distance from the screen.

9. The method of claim 8 , further comprising:

receiving, by the system from the second device, an indication of the screen pixel length of the display device.

10. The method of claim 8 , wherein the data relating to characteristics of the camera comprise a focal length and a sensor size of the camera.

11. The method of claim 10 , wherein the data relating to characteristics of the image obtained by the camera of the display device comprise a camera pixel height of the image and a camera pixel height of the display device within the image.

12. The method of claim 11 , further comprising:

determining, by the system, a visual angle of the display device prior to transmitting the instructions to the second device to output for display at the display device the object.

13. The method of claim 8 , wherein the object displayed at the display device is an optotype, further comprising:

receiving, by the system, an indication from one of: the first device or the second device of user input from a test subject proximate to the first device in response to the displayed optotype.

14. The method of claim 13 , further comprising:

determining, by the system based at least in part on the indication of the user input provided by the test subject in response to the optotype displayed at the display device, at least one of: a diagnosis for the test subject, a lens prescription for the test subject, or information to be provided to a doctor to determine a diagnosis or a lens prescription for the test subject.

15. A non-transitory machine-readable storage medium comprising machine-readable instructions for causing a processor to execute a method for conducting a vision test, comprising:

pairing a first device to a second device through an identifier;

receiving, from the first device, data relating to characteristics of a camera operably coupled to the first device and relating to characteristics of an image obtained by the camera of a display device operably coupled to the second device;

determining a screen pixel length of the display device; and

transmitting instructions to the second device to output for display at the display device an object at a desired visual angle in response to the data received from the second device and the screen pixel length, while the first device is positioned at an arbitrary distance from the screen.

16. The non-transitory machine-readable storage medium of claim 15 , wherein the data relating to characteristics of the camera comprise a focal length and a sensor size of the camera.

17. The non-transitory machine-readable storage medium of claim 16 , wherein the data relating to characteristics of the image obtained by the camera of the display device comprise a camera pixel height of the image and a camera pixel height of the display device within the image.

18. The non-transitory machine-readable storage medium of claim 17 , wherein the object displayed at the display device is an optotype, and wherein the system is further configured to receive an indication from one of: the first device or the second device of user input from a test subject proximate to the first device in response to the displayed optotype.