ABSTRACT. To study the effect of exogenous vitamin E on its plasma and eye tissue levels, we administered 100 mg/kg of dl-a-tocopherol either by intravenous, intramuscular, or oral routes in 3-day-old newborn kittens. Controls did not receive the drug. a-Tocopherol levels in the plasma, retina, choroid, and vitreous were analyzed by high-performance liquid chromatography at selected intervals following drug administration. Our results showed that after intravenous administration of vitamin E, the retinal atocopherol levels increased 300 and 500% the baseline value at 2 and 4 h, respectively. By contrast, comparable retinal levels were achieved at 24 h following intramuscular administration and 72 h following oral administration. In the intravenous group high retinal levels were maintained up to 168 h, while in the intramuscular and oral groups retinal levels continued to increase up to 192 h. Irrespective of route of administration, the retinal concentration of atocopherol remained high even when the plasma levels were declining; plasma levels did not reflect retinal levels at any time. Following exogenous vitamin E administration, a-tocopherol levels increased both in the choroid (4 to 6 times the control) and in the vitreous (1.5 to 4 times the control). Significant differences in tocopherol levels were also seen between the eyes in the same animal in all groups. Our studies suggest 1) a single dose of vitamin E by intravenous, intramusuclar, or oral routes increases retinal levels from 3 to 5 times the control levels. However, peak retinal levels are achieved earlier by parenteral than by the oral route. 2) In addition to the retina, a significant amount of vitamin E is transferred to the choroidal and vitreal tissues. 3) Plasma level does not reflect retinal level. 4) Following vitamin E supplementation by any route, the retinal a-tocopherol levels could vary significantly between the eyes in the same animal. (Pediatr Res 22: 16-20,1987) Abbreviations administered in these studies for its antioxidant effect in the retina and the lungs, respectively (8,9). Although the local concentration of a-tocopherol is considered crucial for its antioxidant effect, little is known about the disposition of vitamin E in the eye tissue following exogenous administration. Nishida and Tagari (10) reported that in preterm neonates, retinal levels increased 30 h after intramuscular administration of vitamin E; however, plasma levels were not presented herein. We measured a-tocopherol levels in the retina, choroid, and vitreous obtained at autopsy from 12 preterm infants (1 I). In these cases high serum levels were associated with high retinal levels, but because of wide variation in the time of oral vitamin E administration and the age at death, no correlation could be established between the serum and retinal values. Other than these two studies, to our knowledge, there are no reports examining retinal levels of vitamin E in human neonates. Although both oral and parenteral preparations of vitamin E have been used in clinic...
Background to describe the effect of ultraviolet rays dissipated during corneal collagen crosslinking on cataract development in keratoconus patient in Cairo, Egypt. Methods We performed a descriptive prospective study that will assess the influence of uneventful corneal collagen crosslinking in management of keratoconus on the crystalline lens clarity in one hundred Eye by oculus pentacam nucleus staging (PNS) for patients attending the specialist eye hospital at the military medical complex of Kobri el Kobba in collaboration with Al-Azhar university hospitals diagnosed from January 2021. Results Our study reported that corneal collagen crosslinking has a highly significant effect in developing lens opacities specially the older age and small AC depth and reported also its affection on visual acuity. Conclusion Corneal collagen cross linking as a method of stabilizing keratoconus progression results in significant changes and increase in the densitometry of the crystalline lens which is a problem that increase the risk in the development of cataract, this is particularly in patient more exposed to ultraviolet rays and pre CXL high lens densitometry.
SUMMARY Twelve antineoplastic drugs were evaluated for their toxicity when used in vitrectomy infusion fluid. These drugs may have implications in the prevention of cellular proliferation inside the eye.
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