One in 100,000 cases of blindness with orbital decompression is just a guess.
That it is because it is unlikely that 100000 orbital decompressions have been performed in the history of mankind. Now if that is the number then the risk of blindness from all causes is much, much higher than 1 in 100000. It is realistically much more like 1 case of blindness for every 500 orbital decompressions. Even this risk is acceptable for someone who is disfigured by thyroid eye disease. However, for a cosmetic concern, the enthusiasm to accept this risk may be much less. Without an actual photograph it is hard to know if you are appropriately concerned or inappropriately concerned with the prominence of your eyes.
Cosmetic orbital decompression
Orbital decompression is for treatment of bulgy eyes, which can result from other causes besides Graves disease, such as congenital. Risk of major complications (such as blindness) is extremely low (one in 100,000 or less). I have more information on my website link provided. See an oculoplastic surgeon for evaluation.