Avoid the bridge of the nose, the area between the eyebrows and the forehead for facial fillers, and above all don't go to an unlicensed injector to save money

Top value
Evidence B
Buys life
Free
Takes minutes
No willpower

In plain words

Among people who went blind after a filler injection, more than half had it in the nose, followed by between the eyebrows, the forehead and the nasolabial folds, and over 80% involved hyaluronic acid. Only about 20% of the people who lost sight recovered it fully, just over 10% partly, and nearly 20% also had brain injury. No rescue method works reliably at present, so the only option is to avoid these areas beforehand.

Cost: Free. You just have the injection somewhere else, or don't have it.
What you get: Cases reported in journals around the world were pooled and counted. From January 2015 to September 2018 there were 48 new cases of partial or complete vision loss after filler injection. The most common site of the incident was the nose, at 56.3%. Next came between the eyebrows at 27.1%, the forehead at 18.8% and the nasolabial fold (the groove running from the nose to the corner of the mouth) at 14.6%. In 81.3% of cases the filler was hyaluronic acid. Skin changes occurred in 43.8%. Central nervous system complications (problems in the brain) occurred in 18.8%. 10 cases (20.8%) recovered their vision completely, 8 (16.7%) partially, and the rest did not recover. The authors concluded that management differs widely between centers and that no treatment has been proven to work consistently.
Notes: These figures come from counting the cases reported in journals one by one. They include only the people who had a problem, not the total number of people who got injections. So there is no way to calculate “the chance of going blind from one injection”; all that can be seen is which sites have more incidents and that afterward it is mostly impossible to recover. That is also why the evidence is rated B. What proper facilities do to lower risk is routine anyway: find out first how the blood vessels run beneath the area to be injected, use a blunt-tipped cannula rather than a sharp needle, inject a small amount at a time while withdrawing, and have hyaluronidase ready beforehand. Every one of these requires that the person doing it is a trained doctor, which is also the reason not to go through unofficial channels. Before having it done, check first as in §28.2 (check the facility's license and the attending physician).
Evidence grade: B : Supported by research but without a precise number, or based on small or single studies.
Sources: Beleznay K et al. (2019). Update on Avoiding and Treating Blindness From Fillers: A Recent Review of the World Literature. Aesthet Surg J. https://doi.org/10.1093/asj/sjz053

Translated from the Chinese original. Original book, section 28, tip 3. This section is about health and medicines. It is general information, not a substitute for a doctor’s diagnosis or prescription. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer