OPHTHALMOMETER MEASURING TECHNIQUE Aligning the Instrument Cover one of the patient’s eyes with the occluder. It is best to always start by measuring the right eye with the left eye covered. The instrument should be set to the VIEW setting with the lever which is up on the body of the instrument just in front of the eyepiece. This illuminates the eye. Position the instrument with the joystick and vertical height knob such that the crosshair is in focus and centered in the pupil.