Review Question - QID 210575

A 21-year-old woman presents to her primary care doctor for an initial visit. She is a Syrian refugee and arrived in the United States 2 weeks ago. She has been living in refugee camps throughout Jordan and Turkey for the past 2 years. She has a 3-year-old son and reports that she has limited her food intake in order to ensure that her son has adequate nutrition. She reports decreased vision most noticeable over the past 6 months that is worse in low-light settings. She also reports severe dry eyes that have not improved with eye drops. She has no known past medical history and takes no medications. Her body mass index is 18.1 kg/m^2. On exam, she appears lethargic but is able to respond to questions appropriately. She has dry mucous membranes and decreased skin turgor. Her conjunctiva appears dry, thickened, and wrinkled. There is a small corneal ulcer on the lateral aspect of the left eye. This patient's symptoms are most consistent with a deficiency in a vitamin that contributes to which of the following processes?