Visual acuity is our visual system’s ability to distinguish details clearly from a distance and under specific conditions. Therefore, it shows us the possibility of seeing details of an object on a uniform background or of seeing that two very close objects are, in fact, separate.
Visual acuity is measured using optotypes that the patient has to identify using their far sight and also reading using their near sight. The most well known optotype is the Snellen test, which involves lines of letters or numbers ranging from large to small. The last line that a patient can read properly determines their visual acuity and it is described with a decimal value (1.0) or a percentage (100%).
Visual acuity measurement is an essential part of any eye test as it tells us the patients exact vision and, if it has gotten worse, it can show the existence of an eye pathology including cataracts, age-associated macular degeneration (AMD) and diabetic retinopathy.