Well, bad eyesight may refer to higher than a -6.00(600 degree) of myopia. From the result of your optical test, containing some terms and abbreviations, some numbers on your eyeglass prescription mean different but specify your prescription. "OD" and "OS" mean the "right eye" and "left eye". Sphere (SPH, amount of lens power), cylinder(CYL, amount of lens power for astigmatism), axis( added magnifying power) and prism( amount of prismatic power), both of which help to correct nearsightedness or farsightedness. In general, sphere, add and cylinder power will appear in diopters. Your degree is normal. I have -3.00 prescription eyeglasses, and go to my optician regularly to see some possible increase of the degree. In addition, the sharpness of our vision will decline with the deepening diopter, extended axial length and some fundus' pathological deterioration. As we all know, eye fatigue has a lot of eye health hazards. The more time you sit in front of your computer or TV, the higher your degree.