In the case of hyperopia, the situation is slightly more complex. In this refractive error rays of light from a distant object are brought to a focus behind the eye. This is because the eye is either too short in axial length (‘from front to back’) or because the cornea (see above) is relatively flat or insufficiently curved and as a consequence does not have sufficient focusing power. Additional power is required therefore and hence positive or plus lenses are required.
The complicating factor in hyperopia is that younger patients can supply some or all of the additional power required by a process of accommodation in which the crystalline lens inside the eye changes its shape and compensates for the refractive error. The ability to do so however declines with age and ultimately all hyperopic patients will require optical correction both for distance and for reading.