Cataract and Abnormalities of the Lens

Bellows, John G.

doi:10.1097/00006324-197606000-00012

Cited by 20 publications

(11 citation statements)

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“…In some instances lenticular ascorbate concentration may also be low. In rat lens, for example, it is barely detectable (11). In view of the proposal that aqueous humor ascorbate functions as a scavenger of photochemically produced *°2 and its derivatives, the mechanism of such scavenging in low ascorbate situations is intriguing.…”

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confidence: 99%

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Light-induced damage to ocular lens cation pump: prevention by vitamin C.

Varma¹,

Kumar²,

Richards³

1979

Proc. Natl. Acad. Sci. U.S.A.

179

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The cation pump activity of the ocular lens was damaged by exposure to light in the presence of riboflavin phosphate. The intensit of ight was similar to that used for reading purposes. The observed light-induced damage was due to superoxide or its derivatives, the superoxide being produced photochemically. Such damage was attenuated by vitamin C in amounts comparable to that in the aqueous humor. Thus, a new role for the high ascorbate level present in the anterior chamber fluid and the lens has been suggested. Ascorbate in other tissues also might have this novel physiological function of protecting against damage due to superoxide and its derivatives produced during normal cellular oxidation. The concentration of ascorbic acid (vitamin C) in the aqueous humor of man, monkey, and many other animals is one of the highest among the various body fluids (1). The prevalence of this high level of ascorbate has been attributed to the ability of the ciliary epithelium to transport this compound actively from the plasma to the posterior chamber through the blood aqueous barrier (2). For reasons undefined at the present time, the concentration of ascorbate is also high in tissues surrounding the aqueous humor-namely, the cornea and the lens. The concentration in the latter tissue in many instances is second only to that in adrenals (1). Although the importance of ascorbic acid in hydroxylation reactions is known in many tissues, the relevance of a high ascorbate level in the aqueous humor and the lens is not precisely known, although it has been suggested that photochemical oxidation of ascorbic acid in the anterior chamber serves to provide hydrogen peroxide to the lens. The peroxide, in turn, may regulate the tissue hexose monophosphate shunt through the following series of interlinked reactions

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confidence: 99%

“…Rat lenses were used in these experiments to minimize the effect of endogenous ascorbate, the native level of ascorbate in the lenses of this species being negligible (11). Animals weighing 100 g were killed by decapitation and the lenses were dissected out after enucleation.…”

mentioning

confidence: 99%

Light-induced damage to ocular lens cation pump: prevention by vitamin C.

Varma¹,

Kumar²,

Richards³

1979

Proc. Natl. Acad. Sci. U.S.A.

179

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“…Numerous reports have confirmed the clinical impression that either a low calcium-phosphorus ratio is the single factor common to all the above patients [1], or increased calcium-phosphorus product, despite hypocalcemia, play a role in cataract formation [3]. As early as 1944, cataracts, histologically identical to hypoparathyroid cataracts, were induced in vitamin D-deficient rats upon elevation of the dietary phosphate to calcium rate [12]. This mechanism is compatible with the deposition of calcium-phosphate salts in the lens, and therefore the incidence of cataracts is expected to increase with elevation of the serum calcium-phosphorus product.…”

Section: Discussionmentioning

confidence: 99%

A Rapidly Progressive Cataract in a Patient with Autoimmune Hypoparathyroidism and Acute Liver and Renal Failure

Haviv

Safadi²,

Zamir

1999

Am J Nephrol

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Cataract is a well-known complication of hypoparathyroidism, albeit the mechanism is obscure. The progression of cataract is typically slow in patients with idiopathic hypoparathyroidism. We describe a case of an extremely rapid evolution of typical hypocalcemic cataracts in a patient with familial autoimmune hypoparathyroidism during acute idiopathic hepatic and renal failure, while serum calcium and phosphorus were unbalanced. Physicians and ophthalmologists must be aware of cataracts developing rapidly in the setting of such metabolic derangements.

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“…It is well known that cataracts arise fol lowing retinitis pigmentosa in human eye [Bellows and Bellows, 1975]. From the above data, it can be inferred that in the human eye with retinitis pigmentosa, the lens is exposed to abnormal vitreous and aqueous humors which may contain poten tially harmful substances which are normally prevented from entering the eye by bloodocular barrier(s).…”

Section: Discussionmentioning

confidence: 99%

Effect of Sodium Iodate Injection on the Development of Galactose Cataract in the Rat

Taura

Reddy²

1988

Ophthalmic Res

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The effect of sodium iodate injection on the development of galactose cataract in the rat was investigated clinically and biochemically. Galactose cataracts were induced in animals which had been injected with a single dose of sodium iodate and compared with those given a saline injection. The degeneration of retinal pigment epithelium was observed electron microscopically after sodium iodate injection. A slit lamp examination of the lens showed that, in animals injected with sodium iodate, galactose-associated lens alterations progressed faster, and mature cataract development was achieved earlier than in the saline-injected animals. Biochemical data which indicated a significantly higher concentration of Na⁺ and lower concentration of K⁺ in lenses of sodium iodate-injected animals confirmed the above clinical data. The level of galactitol was higher in lenses of sodium iodate-injected than those of saline injected animals. Acceleration of the development of galactose cataract following sodium iodate injection is apparently due to the higher level of galactose entering the aqueous humor because of breakdown of blood-ocular barriers.

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Cataract and Abnormalities of the Lens

Cited by 20 publications

References 0 publications

Light-induced damage to ocular lens cation pump: prevention by vitamin C.

Light-induced damage to ocular lens cation pump: prevention by vitamin C.

A Rapidly Progressive Cataract in a Patient with Autoimmune Hypoparathyroidism and Acute Liver and Renal Failure

Effect of Sodium Iodate Injection on the Development of Galactose Cataract in the Rat

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