@Coriander Very limited advice from -7+ dioptries, but what helped me stop it from decreasing further during start of uni (it'd climb up a dioptrie/dioptrie and a half for a while after) is therapy with higher dioptries for half a month every few months. Slowly climbing in dioptries (up to like -13 - -15) and training in reading the last line on the standardised test, until it becomes consistently good and increasing the dioptries. Plus doing a full eye relaxation excercise afterwards.
Tried doing the zog-recommendation excercises of changing eye focus for a while, etc. but that did nothing at all.