I am a -5.75 in both eyes. i don't know what is considered severe but just out of curiousness. should i be worried about retinal detachment later in life?

Not severe: This is higher than most, but not severe but does not protect you from never having retinal problems. I recommend a full dilated eye exam once a year to be safe and earlier if you note any new significant changes in vision.

Higher Risk: Being that near-sighted does pose a higher risk of retinal detachment than someone without near-sightedness. Nonetheless, the risk is still very low. The best way to address this concern is to get an annual dilated eye exam by an ophthalmologist to check for any signs that could predispose to a retinal detachment, such as lattice degeneration.