Well OaW, I was answering "tke"'s initial message "Know your Cataract", and his question at its end asking if anyone had an idea about how to reach his PSC Cataract.
You ask me what blog it is, but unfortunately the whole blog is in french (and it doesn't usually deal with eye medicine either.).
"Ch" deals with the number of dilutions and is the most common unit in measures used in homeopathy (I think) - in France at least. Your doctor or pharmacist/chemist would know I reckon.