A person with hyperopia has a near point that is further away than the typical near point for someone their age, and hence the person is unable to bring an object at the typical near point distance into sharp focus. A
corrective lens can be used to correct hyperopia by imaging an object at the typical near point distance onto a
virtual image at the patient's actual near point, at distance . From the
thin lens formula, the required lens will have
optical power given by P \approx \frac{1}{D}-\frac{1}{\mathit{NP}}. The calculation can be further improved by taking into account the distance between the
spectacle lens and the human eye, which is usually about 1.5 cm: P = \frac{1}{D-0.015\;\text{m}}-\frac{1}{\mathit{NP}-0.015\;\text{m}}. For example, if a person has and the typical near point distance at their age is , then the optical power needed is where one
diopter is the
reciprocal of one meter. ==References==