50 y/o, WF. Near sighted. Routine eye exam today. Have worn contacs for many yrs, 5.0 power for 7 yrs. Wear reading glasses over contacs PRN, currently 2.5 power. Have had increasing difficultly seeing @ a distance over past yr. Exam today revealed eyes reversing, now 4.25. MD said not common, but can occur, stating various medical reasons, eg diabetes , certain meds. I have no medical problems, & do not take any meds other than Ibuprofen on occasion. Left office with 4.25 power contacs, & could see much better, maybe 30%. ?- how common is this, & what other reasons could cause this to happen?