Nick To be honest, it is my fault i should have added it vitamin D. Thank you for your comment and i am glad i made you curious. To respond on your question, generally the eye is the other organ other than the skin which directly exposes in the sunlight.
You know apart from the problems in case of any lack of vitamin D such as osteoporosis, in the eye can be seen uveitis, macular degeneration, and dry eye syndrome.
EXTRA: In an animal-based study, where they tried to find if vitamin D has any benefit in glaucoma, they found that the anti-inflammatory effects of vitamin D could protect endothelial cells from metabolic damage and oxidative stress. So, can be used alongside with the eye drops