Allergic Contact Dermatitis from Eyedrops
This is a clinical conundrum which really demands every single bit of your clinical diagnostic skills. When we think about periorbital skin changes, we think about atopic dermatitis, allergic contact dermatitis and dermatomyositis. First, think atopic derm. usually on the lower lids, usually associated with diffuse, poorly demarcated lichenification on the lower lid (with occasional upper lid involvement) and often with other stigmata of atopic dermatitis (such as Dennie-Morgan folds, allergic shiners and nasal creases). The heliotrope rash of dermatomyositis is in the distribution of the orbicularis oculi muscle (which, incidentally, may be tender because of the underlying myositis), is swollen and pinkish-violet. It is almost always symmetrical.
This patient has an asymmetrical rash that looks like she suffered from drippage on her left side, it is lichenified, the rash extends well beyond the orbicularis and is far more prominent on the lower lid than the upper. There are no other stigmata of atopic dermatitis. Given this clinical picture, the best bet would be allergic contact dermatitis.