Could be medication side effect - especially lexapro. Could be side effect from herbal remedy or over the counter meds - especially weight loss products, motion sickness patch, others. Watch out for angle closure glaucoma (mid dilated, fixed or sluggish pupils, severe eye pain, headache, halos around lights, vision loss, vomiting.) Occasionally, certain other toxic substances around the house can make you feel ill and affect pupil size. She could also just be overmedicated. Basically, you need to see your primary care doctor first and an ophthalmologist also.
Michael Kutryb, MD