Well the complicated bit is pretty important, it's not...

Well the complicated bit is pretty important, it's not simply making it better for existing customers (as you're right that wouldn't result in any growth as everything would be canabalised), but it makes the procedure accessible to a significantly larger market (many multiples larger), which explains the very high growth rates we've observed in the USA so far. Only a small number of the top doctors could perform the old procedure, and due to the difficulty and lack of efficiency/ease it really wasn't worthwhile from the perspective of maximising profits by doctors. Of course it was still performed due to the high efficacy and safety in addition to not requiring any sort of implant or testing (highly desirable for a patient), but most doctors would simply have done another procedure due to these issues.

The new device makes it one of the fastest procedures now, unlocking a much larger addressable market and accessing many doctors who wouldn't have used the old device. Now doctors can get the high efficacy and safety and lack of implants/tearing without having to compromise on speed and efficiency. This is especially important for combo -cataract but also standalone procedures as well. The company presents this quite well, with a graphic on most presentations of the previous addressable market, and the much larger addressable market (majority being cataract surgeons) who can now access this procedure thanks to the changes.