Your father most likely has dry
eye syndrome. Mine lead to corneal erosion. There is an explosion of research now on Lactoferrin for many purposes: ulcers, gastrointestinal flora balance, antibacterial, anti-inflammatory, osteoporosis, autoimmune disorders such as arthritis, dry eye syndrome, et al.
Here is a url that might interest you re dry eye syndrome:
This particular study used 270 mg per day.