Classification of CNV type based on Morphometric Weight.

We define the type of CNV based on the mean morphometric weight during a three month window. A MW≥0.75 throughout the window indicates that most stalk cells lie between BrM and the RPE (in the sub-RPE space) and do not contact the POS. We therefore assign the time window to Type 1. A MW≤0.25 throughout the window indicates that most stalk cells lie between RPE and the POS (in sub-retinal space) and do not contact BrM. We therefore assign the time window to Type 2 CNV. 0.25<MW<0.75 usually indicates that stalk cells occur in both the sub-RPE and sub-retinal spaces. In a few exceptional cases (Table S10) with 0.25<MW<0.75, most stalk cells lie between neighboring RPE cells rather than in either the sub-RPE or sub-retinal spaces (discussed in the Stable Type 3 CNV subsection in supplementary Text S5).