Right now im looking at disruption of endogenous retinoic acid production, which serum retinol might not accurately reflect.
I was looking at a somewhat recent study, and they were not sure if there was a centrally synthesized location being the liver or intestine. I’ve already seen enough studies bacteria could contribute to retinoic acid production or takeaway from.
Vitamin A and the eye: an old tale for modern times
Clinical presentations associated with vitamin A deficiency persist in poor regions globally with the same clinical features as those described centuries ago. However, new forms of vitamin A deficiency affecting the eyes, which have become widespread, as a result of modern societal habits are of increasing concern. Ophthalmic conditions related to vitamin A deficiency require the combined attention of ophthalmologists, pediatricians, internists, dermatologists, and nutritionists due to their potential severity and the diversity of causes. As the eyes and their adnexa are particularly sensitive to vitamin A deficiency and excess, ocular disturbances are often early indicators of vitamin A imbalance. The present review describes the clinical manifestations of hypovitaminosis A with an emphasis on so-called modern dietary disorders and multidisciplinary treatment approaches. The present review also discusses the relationship between retinoic acid therapy and dry eye disease.
Increased suspicion of hypovitaminosis A due to ocular surface symptoms and signals should direct prompt investigation of nutritional and digestive problems followed by interdisciplinary management allowing early diagnosis and treatment of the causes and effects of the majority of diseases related to hypovitaminosis A.
There have been concerns regarding the reliability of blood concentration measurements as the liver is able to sustain normal levels even in extremely vitamin A-deficient states
Hypovitaminosis A should be suspected in all cases of night blindness, ocular surface foreign body sensation, and photophobia without other evident causes. Crying without tearing is another relevant symptom of hypovitaminosis A. Recurrent hordeolum, meibomian gland dysfunction identified by gland dropout or inflammation with thickened lipid secretion, corneal epithelial defect, conjunctiva metaplasia (where Bitot’s spot is an advanced form and a hallmark), and diffuse punctate keratitis also represent signs suspicious for hypovitaminosis A.
This was pulled from another paper,
“Various animal tests have revealed that tretinoin (all-trans-retinoic acid) is very efficient in reversing xerophthalmic changes compared to retinol [113].”