How safe and effective is it to have your lenses replaced with artificial multifocal lenses when cataracts are not present?

Patients with your level of myopia are notoriously difficult to satisfy. Currently, you could take off your glasses are read pretty well compared to your distance vision.
The risk of clear lens replacement surgery is the same as for cataract surgery.
There is no perfect lens that gets you out of glasses 100% of the time for distance, intermediate, and near vision without side effects in 100% of patients.
A trial of multifocal contact lenses is often useful if you don't have cataract or have only a mild one. If you love the vision and want to see like that 100% of the day and night, then a multifocal implant or the new Symphony implant might be for you. If you don't like the night vision or feel things look waxy or feel the near vision is inadequate then don't pick a multi-focal. Most of my patients say the vision with the multifocal contact lens is exactly the same as the multifocal implant. 
I prefer the Crystalens/Trulign over multi-focals or Symphony for presbyopia correction. Starburst and Halos are almost unheard of with Crystalens/Trulign. The distance and intermediate (computer, dashboard, ATM, counter-tops) from over a 1000 of my patients are averaging ~99% of the time independence from glasses for those distances. Glasses independence for near vision seems to average about 70% of the time. 
The other thing to consider with Crystalens/Trulign is the lens seems very forgiving or the small changes in prescription the eye may have over time. Many surgeons's charge extra for astigmatism correction for multifocals and say that you need to have very little astigmatism for the lens to work well. So what then when things change a little?
The vision with Crystalens/Trulign seems to be more tolerant of macular degeneration or glaucoma that may develop later. 
You can often boost the near vision of Crystalens/Trulign by doing surgery first on the non-dominant eye and making the eye slightly myopic ( -.50 to -1.00). 

After the age of 50, most surgeons avoid LASIK and similar procedures in favor of intraocular lens surgery like multifocal lenses. This procedure is common and becoming more common as baby boomers are familiar with the idea of elective eye surgery to improve their vision and often don't want to wait until their cataracts are "ripe" to benefit from the latest lens technology. There are several types of multifocal lenses and some of more side effects. There are risks to any surgery including bleeding, infection, high or low intraocular pressure and others. This type of intraocular surgery is the most common surgery performed in the US and also has the distinction of being the most successful. Individual results, of course, can vary.  Talk to your doctor about whether you are a good candidate for this type of surgery and which lens might be best for your lifestyle.

Replacing your natural lens with a multifocal lens is generally safe, but is subject to all of the complications of cataract surgery, which is an identical procedure. One major drawback is that there is no way to show you ahead of time what your vision will be like with the multifocal lenses. Some people do not like the vision with multifocal lenses, because there is typically considerable glare at night.