The machine that can see the image is a medical device called an "Auto Refract-Keratometer". It can tell if you are nearsighted, farsighted, or have astigmatism, and to what extent. It serves as a source of test results and can also be used to measure visual acuity.
The eye collects light from the outside world, bends it, and focuses it so that it can see clearly. However, if the eye does not refract light properly, it can become nearsighted, farsighted, or astigmatic.
Expanded Information
Computerized optometry can be used as diagnostic optometry for soft corneal contact lenses, which does not require dilation of the pupils and can quickly measure the refractive error. Computerized optometry instrument optometry results are all automatically printed, without conversion, generally a few seconds to a few minutes to determine a patient, and can quickly determine the degree of refractive error, for lens correction to provide a more accurate refractive error and interpupillary distance.
The accuracy of the brain optometry is affected by many factors, such as the patient's head and eyes are not well coordinated, moving around, the eye gaze optometry within the target is not concentrated enough, so that the relaxation of the adjustment is not enough, will inevitably affect the accuracy of the results of the refractive error test, and even repeat the examination of the degree of difference is large.