Eye tests are typically conducted by optometrists or ophthalmologists to evaluate a person's vision, assess their visual acuity, and determine any refractive errors or eye conditions. These tests involve reading charts, performing visual tasks, and using specialized equipment to measure aspects such as visual acuity, depth perception, color vision, and the health of the eye.
If you can provide more context or clarify the specific test you are referring to in relation to hot air balloons, I'll do my best to assist you further.