The article is a bit confusing imo. It mentions myopia and also retinal detachment, and sort of implies a link between the two but not does not explain that at all.
The more myopic you are, the higher your risk of retinal detachment, and other eye issues and diseases.
The eye elongating sufficiently will cause the retina to at least partially detach; its size cannot increase, but the surface area of the thing it is attached to is increasing.