In summary, see the vet to rule out more serious causes. If it is due to senile fat atrophy or past trauma and vet simply wants to watch it, then also monitor her eye for dry eye since an enophthalmic eye tends to have dryness. You had asked about supportive supplements: artificial tears, increased water intake, omega-3 supplementation have all been shown by studies to help with dry eye.
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Joanne, Colorado,  2020