Presbyopic patients can use their bifocal or reading glasses during visual acuity testing or simply a +2.50 over the counter reading glasses.
 
Myopic children see very well at near but near testing will not detect the myope who needs reading glasses for the blackboard or distance.  This is overcome by testing children with +2.50 add at near, this will blur the myopic children and disclose the need for distrance glasses.  This +2.50  lens has no visual affect on vision testing of the children without myopia.