Protective role of oral antioxidant supplementation in ocular surface of diabetic patients

Abstract

Aim: To investigate the effect of vitamin C and E supplementation in the levels of nitrite, nitric oxide (NO) related metabolite, and ocular surface parameters in diabetic patients. Methods: 50 patients with non-insulin dependent diabetes mellitus were given vitamin C (1000 mg/day) and vitamin E (400 IU/day) supplementation for 10 days. Nitrite levels in tears were measured by photometric determination before and after vitamin supplementation. Tear function parameters (Schirmer test I, BUT, ocular ferning test) and brush cytology analysis of the conjunctival epithelium were also evaluated. Results: Nitrite levels were found to be significantly reduced (p<0.05) after 10 days of vitamin C and E supplementation. Improved values for Schirmer test, BUT test, and ocular ferning test were also found. Goblet cell density and grading of squamous metaplasia showed a significant improvement. Conclusions: Oxidative stress and free radical production are elevated in diabetes mellitus. Antioxidants, such as vitamin C and vitamin E, probably have an important role in reducing the oxidative damage produced by nitric oxide and other free radicals and improving the ocular surface milieu.

Increased expression of advanced glycation end-products and their receptor, and activation of nuclear factor kappa-B in lacrimal glands of diabetic rats

“…In addition, a clinical study indicated that antioxidant therapy can improve some parameters on the ocular surface of diabetic patients [38]. However, it remains to be clarified whether symptoms associated with the lacrimal gland and/or tear film dysfunction observed in diabetic patients could be improved or reversed by anti-AGE strategies.…”

Optical quality of the diabetic eye: a review

“…[16][17][18][19][20][21][22][23][24][25][26] Some ocular manifestations of DM are associated with lachrymal gland dysfunction and have been related to dry eye. Several clinical studies have demonstrated that people with DM are more vulnerable to dry eye than healthy subjects.…”

“…Dogru et al 17 showed, however, that the conjunctival metaplasia was due to a loss of neurotrophic effects as a result of corneal hypoesthesia, glucose level fluctuation, and metabolic control insufficiency. DM is often associated with increased oxidative stress and free radical production, 23,24 which may damage epithelial tissues such as the conjunctiva and the lachrymal glands. As the tear film is rich in several antioxidants such as ascorbic acid (vitamin C), found in high concentrations in the eye, Peponis et al 24 demonstrated that orally administered antioxidant supplements for a period of 10 days improved the tear film stability and secretion, and the antioxidant properties of vitamins C and E could protect the ocular surface from the attack of free radicals and preserve the integrity of the epithelium.…”

“…86,87 Even though there are no studies evaluating the impact that these factors could have on HOAs in people with DM, these do have a thicker and more convex lens, [54][55][56] can develop premature cataracts, [9][10][11] and suffer a series of changes associated with lachrymal gland dysfunction and dry eye syndrome. [16][17][18][19][20][21][22][23][24][25][26] Patients with DM who undergo laser-assisted in situ keratomileusis are also at a significantly higher risk of developing postoperative epithelial complications, and refractive results tend to be worse compared with healthy people. 88 Few authors have investigated HOAs in people with DM.…”

Diabetes, Oxidative Stress, Antioxidants and Saliva: A Review

“…Experimental study on diabetic rats suggested that nutritional vitamin E supplementation helps fatty acids metabolism and lower lipid peroxidation in rat tissues (50). Oral vitamin C and vitamin E has the ability to lower the oxidative stress in eye (51) and the vascular endothelia function get better in type1 and not type 2 diabetes (52). Vitamin C and Vitamin E, probably have an important role in reducing the oxidative www.intechopen.com Diabetes, Oxidative Stress, Antioxidants and Saliva: A Review 307 damage produced by nitric oxide and other free radicals.…”