Prevention of MBD is simple and can be accomplished by conforming in three main areas.These being.
The supply of sufficient UVB light, with the lack of sunlight in captivity that Iguanas need to stay healthy, you must substitute full spectrum UVB lights of at least 5% UVB output and also check the output which can start to diminish at around 6-12 months, cards / metering equipment, are available that can check the UVB output at a very reasonable price, or if in any doubt replace anyway.
A good healthy diet is required to supply the calcium and vitamins needed to stay healthy, see the care sheet for diet details and also keep in mind that it is sometimes necessary to supplement calcium and vitamins if the intake is down for some reason.
Iguanas need to be at the correct temperature to digest the food and utilize the calcium intake, again further details are in the care sheet section.
So therefore there are no reasons at all why there should ever be cases of MBD in the Iguanas kept by competent Iguana keepers, unless of course you have recently acquired one that is showing early signs due to mistreatment from a previous owner, in which case veterinarian examination would be beneficial to confirm the extent and also to advise on the calcium dosage required to regain health.
Also in extreme cases where you have rescued or adopted an Iguana that is obviously well into the stages of MBD, but again the vet is the best person to advise on the extent of the disease and the treatment.
It would obviously be of great help if the vet you choose is experienced in reptilian care, and you may find help in picking one that is, by asking in forums, reptile groups, asking other owners or alternatively by phoning local vets and asking first if they have good reptilian experience.
There are also links to help you find a vet on my main page and also on my banners and links pages.