How can the spectacle correction be determined if the patient is unable to communicate?
When the patient is not able to read a letter chart but has the mental capacity to understand, then the letters can be pointed to on a corresponding card. If the patient lacks the mental capacity to communicate, the optician, using objective means, determines the spectacle correction. Either the reflected light from the back of the eyes is observed using a special light called a retinascope or a measurement of the spectacle correction can be taken with an auto-refractor.
