This device is used for corrective vision (vision therapy) training and can be used to treat convergence insufficiency.
This Tranaglyph card comes with red/green glasses and instructions for treating binocular vision problems at home.
Please follow your optometrist's instructions and use under proper guidance.
There is a Chinese instruction manual in the package, the same as the instructions in the product description. Please let us know by email if you need an English translation of the manual.