This number can cause strain for reading if you do not use it and strain for distance vision as well. Not uisng this number can also cause a accomodative spasm. This number can also lead to squinting of eyes.
-2.75 number can even be needed for distance vision by people who are straining their eyes or are working on a laptop or pc the whole day.
You can use contact lenes instead of glasses and this number can be removed by the use of laser lasik surgery or contoura lasik surgery.
The axial length of the eye is more than normal by 0.8 mm in with this number which can be measured by a IOL master scan. This kind of number increases the risk of having a retinal deatchment, lattices or holes in the reinta. A retina exam every year is necessary.