Effects of ascorbic acid on UV light-mediated photoreceptor damage in isolated rat retina

Abstract

Concerns have been raised about whether operating microscopes and endoillumination used during ophthalmic surgeries contribute to retinal damage. Despite the recognition that ascorbic acid (vitamin C) helps to protect the eye from light and the abundance of vitamin C in the retina, artificial aqueous humors used during surgery only contain the antioxidant glutathione. To test whether inclusion of antioxidants other than glutathione in surgical solutions might help to preserve retinal integrity, we studied the effects of vitamin C on acute toxicity in isolated rat retinas. Male Sprague-Dawley rats (PND 30+/-2) were sacrificed for retinal isolation. In the presence or absence of vitamin C (1 or 3 mM), retinas were exposed to 302 nm ultraviolet B (UVB) light for 1 h and were incubated for a total of 5 h at 30 degrees C. Retinal damage was assessed by morphological examination and biochemical assay measuring the amount of lactate dehydrogenase (LDH) released from injured cells. In control retinas, LDH release was significantly increased after UVB exposure. The presence of 1 mM vitamin C in the incubation media significantly reduced LDH release during the post-incubation period following UV exposure. No difference was found between 1 and 3 mM vitamin C. Microscopic examination revealed that disorganization in the outer nuclear layer after UVB exposure was markedly attenuated by administration of 1 mM vitamin C. Vitamin C (1 mM), a concentration found in the anterior chamber in humans, but not glutathione, prevented phototoxic injury following UV exposure. Although vitamin C itself cannot be used in intraocular irrigating solutions because of adverse interactions with iron released during bleeding, inclusion of antioxidants equivalent to vitamin C should be considered to help protect the retina from intraoperative light toxicity.

Involvement of Illumination in Indocyanine Green Toxicity After Its Washout in the Ex Vivo Rat Retina

“…Similar degeneration is also observed in ex vivo retinal preparations. We previously found that isolated retinas exposed to ultraviolet B radiation exhibit phototoxicity that is limited to the ONL 42. In the present study, illumination for 3 h after ICG exposure induced remarkable morphological damage that was predominant in the ONL without affecting neurons in either the GCL or INL.…”

The Dysfunction of the Trabecular Meshwork During Glaucoma Course

“…The aqueous fluid has 0.1–0.2% of the concentration of plasma proteins but a higher concentration of amino acids than plasma. Ascorbate (Ringvold et al, ) and lactate concentrations (Tokuda et al, ) as well as bicarbonate are also high in the AH (Gerometta et al, ). Glutathione and vitamin C defend against free radicals in‐ and outside of cells (Cardoso et al, ).…”

Sensitivity of Ocular Anterior Chamber Tissues to Oxidative Damage and Its Relevance to the Pathogenesis of Glaucoma

“…Ascorbate, lactate, and bicarbonate concentrations are also high in the AH. [5][6][7] The rate of AH production is approximately 2 to 2.5 mL/min. Approximately 1% of the AC and 3% of the posterior chamber volume of AH is replaced each minute.…”