My contact lens prescription is significantly different from my glasses prescription. Is this normal?
A small difference. Is normal. A significant difference would be unusual but it could just be the way it is written in a different format.
Yes. It is due to a differing vertex distance or where the corrective lens is placed in relationship to the corneal surface - this is normal.
My contact lens prescription is different from my glasses prescription. Is it supposed to be like that?
Yes. Especially if you are very nearsighted or farsighted, your contact lens and glasses should have different prescriptions. The optics behind this phenomenon cannot be explained in this short space, but the difference between glasses and contacts is always greater with larger prescriptions. As long as you see well with both, they are probably right for you.
Yes. The optical principle is lens effectivity. As any lens is moved away from your eye it becomes inherently more powerful (positive) the inverse is also true, as a lens is moved to eye, becomes weaker (negative). So contacts and glasses are adjusted accordingly only if it will affect the final clinical outcome.
Close. Commonly it is slightly higer like -4.50 and -5.00 but this depends in part on the goal and how long since your last examination. Also at your age there is the issue of bifocals due to near vision needs. Useful to check with your ophthalmologist for the best information on this.
Not really. The contact lens rx is determined from a refraction for glasses - sometimes trial fitting is necessary since the actual numbers are different due to an optical property called vertex distance.
No. The power is different from the glasses to contact lens due to the different distances of the correction from the eye. Also contact lens rx requires a base curve and diameter, which is determined during a contact lens fitting.
Slightly tricky. Mostly straightforward if there is no astigmatism but a little involved if there is astigmatism. I assume you are ordering lenses online and will need that conversion. There is also some experience functions depending upon the type of lens. Check with your ophthalmologist to get this done for you. Optometrists are unlikely to do it as they prefer to sell you lenses.