long-sightedness. What is a vision defect? An eye is described as having a vision defect when it has less than normal vision. The term is very imprecise, as a vision defect can have a wide variety of causes [...] The visual impairment caused by other sight defects, such as night blindness or amblyopia, cannot be corrected. What is amblyopia? Amblyopia is a vision defect where the visual loss cannot be corrected by

acuity is also an absolute necessity when using magnifying vision aids. In order to correct vision defects, ophthalmologists and opticians need to determine the corrected visual acuity (lat. visus cum co