In Melb you wouldn't be on anti-malarials, but in the tropics in some places people use them, and the older ones would dilate the irus over time letting in more light. Maybe the new ones don't have the side effects, - haven't used them. Posted some time back, (don't know where now), about how my new darker sunglasses became too dark after I stopped taking the pills and the eyes reverted back. If you take any medication, for anything, check out the side effects over time on your eyes.