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It's the leading cause of irreversible blindness worldwide, and it is predicted to affect 76 million people by the end of the year.
There is still no proven cure for the disease, but treatment can reliably slow or halt deterioration in most cases.
Up to 50% of those affected are not even aware.
Testing is available, but people need to have vision checks to detect the condition which is much like high blood pressure — silent, but potentially damaging.