Riboflavin Deficiency Induces Ocular Surface Damage

Abstract

Purpose: To examine the conjunctiva and cornea of riboflavin-deficient rats with scanning (SEM) and transmission (TEM) electron microscopes. Materials and Methods: Three-week-old Wistar Kyoto rats were fed a riboflavin-deficient diet (0.05 mg riboflavin/100 g) for 3 months. As a recovery experiment, rats which had been on a riboflavin-deficient diet for 3 months were given water with 1 mg riboflavin/300 ml for 2 months. The conjunctiva and the cornea were examined with SEM and TEM. Results: The serum riboflavin level was significantly lower in the riboflavin-deficient group than in the controls. In rats on a riboflavin-deficient diet for 3 months, SEM showed decreased microvilli and microplicae in the superficial epithelium of the conjunctiva and a decrease in the number of goblet cells. The cornea showed many dark cells and a marked decrease of microvilli and microplicae. In the riboflavin-deficient rats, TEM of the conjunctiva showed a decrease of microvilli and microplicae in the most superficial epithelial cells, a decrease in the layers of the epithelium and a marked decrease in the number of goblet cells, while the cornea had decreased microvilli and microplicae in the superficial epithelium, dark wing cells, loss of the basement membrane and hemidesmosomes of basal cells, cell debris and degenerative stroma cells and deposits of dense bodies in the subepithelial layer of the stroma. In rats recovered from riboflavin deficiency, the conjunctiva and cornea showed no abnormalities. Discussion: Riboflavin plays a role in the development and maintenance of the surface structures of epithelial cells. Riboflavin may also be necessary for the development and maintenance of goblet cells. Conclusion: Riboflavin is essential for maintaining the structure and function of the ocular surface.

Impression cytology with scanning electron microscopy: a new method in the study of conjunctival microvilli

“…9,10 Riboflavin, zinc, vitamin E, vitamin A, and magnesium deficiency was found to cause alterations of microvilli and goblet cells of the corneo-conjunctival epithelium in rats. [25][26][27] This suggests that the exchange of nutrients between the tear film and the conjunctival epithelium is altered in this condition. However, it is not known whether the alteration originates in microvilli or goblet cells.…”

Corneal cross-linking

“…22 In addition to direct damage to microbes, mechanisms of action include increased corneal resistance to M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT enzymatic degradation 141 , prevention of microbial replication via intercalation of riboflavin with the pathogen's DNA, 107 generation of reactive oxygen species with direct cytotoxic effects, 79,80 and alteration the ocular surface to be a more hostile environment for microbes. 145 In vitro and animal studies demonstrate efficacy of cross-linking as adjunct treatment of challenging keratitis pathogens such as methicillin-resistant Staphylococcus aureus, 101,131 Candida albicans, Aspergillus fumigatus, 129 Fusarium solani, 36 and Acanthamoeba 10 [ Table 2]. …”

Riboflavina: uma vitamina multifuncional

“…Vascularização e opacidade na córnea e até mesmo cataratas têm sido relatadas em animais alimentados com dietas pobres em riboflavina. Acredita-se que fotorreceptores dependentes de riboflavina (criptocromos) desempenham uma função importante na adaptação ao escuro e, portanto, a dieta de riboflavina poderia influenciar na adaptação ao escuro através desses fotorreceptores por interação com a vitamina A ou de forma independente 17,18 . Finalmente, a deficiência de riboflavina pode interferir no metabolismo de outros nutrientes, principalmente no metabolismo de outras vitaminas B, tais como folato, cianocobalamina (vitamina B 12 ) e piridoxina (vitamina B 6 ) 13 .…”