The optician prescribes a corrective lens of power +2.5D. What does this mean?
1
The lens is a combo of 2 concave lenses, with powers 2D and 0.5 D
2
The lens is convex with power 2D
3
The lens is a combo of 2 convex lenses, with powers 2D and 0.5D
4
The lens is concave with power 2.5D