Some surveys have shown a link, but others which followed people over longer terms have not. Inadequate vitamin C
Low vitamin C intake and serum levels have been associated with greater cataract rates. However, use of supplements of vitamin C has not demonstrated benefit. Medications
Some medications, such as systemic, topical, or inhaled corticosteroids, may increase the risk of cataract development. Corticosteroids most commonly cause posterior subcapsular cataracts. People with schizophrenia often have risk factors for lens opacities (such as diabetes, hypertension, and poor nutrition) but antipsychotic medications are unlikely to contribute to cataract formation. Miotics and triparanol may increase the risk. Post-operative
Nearly every person who undergoes a vitrectomy—without ever having had cataract surgery—will experience progression of nuclear sclerosis after the operation. This may be because the native vitreous humor is different from the solutions used to replace the vitreous (vitreous substitutes), such as BSS Plus. This may also be because the native vitreous humour contains ascorbic acid which helps neutralize oxidative damage to the lens and because conventional vitreous substitutes do not contain ascorbic acid. Accordingly, for phakic patients requiring a vitrectomy it is becoming increasingly common for ophthalmologists to offer the vitrectomy combined with prophylactic cataract surgery to prevent cataract formation. Other diseases
Diagnosis
Classification
Cataracts may be partial or complete, stationary or progressive, hard or soft. Histologically, the main types of age-related cataracts are nuclear sclerosis, cortical, and posterior subcapsular.Nuclear sclerosis is the most common type of cataract, and involves the central or nuclear part of the lens.
Riboflavin is involved in maintaining normal circulating levels of homocysteine; in riboflavin deficiency, homocysteine levels increase, elevating the risk of cardiovascular diseases. Redox reactions
Redox reactions are processes that involve the transfer of electrons. The flavin coenzymes support the function of roughly 70-80 flavoenzymes in humans (and hundreds more across all organisms, including those encoded by archeal, bacterial and fungal genomes) that are responsible for one- or two-electron redox reactions which capitalize on the ability of flavins to be converted between oxidized, half-reduced and fully reduced forms. FAD is also required for the activity of glutathione reductase, an essential enzyme in formation of the endogenous antioxidant, glutathione. Micronutrient metabolism
Riboflavin, FMN, and FAD are involved in the metabolism of niacin, vitamin B6, and folate. The synthesis of the niacin-containing coenzymes, NAD and NADP, from tryptophan involves the FAD-dependent enzyme, kynurenine 3-monooxygenase. Dietary deficiency of riboflavin can decrease the production of NAD and NADP, thereby promoting niacin deficiency. Conversion of vitamin B6 to its coenzyme, pyridoxal 5-phosphate synthase, involves the enzyme, pyridoxine 5-phosphate oxidase, which requires FMN. An enzyme involved in folate metabolism, 5,10-methylenetetrahydrofolate reductase, requires FAD to form the amino acid, methionine, from homocysteine.Riboflavin deficiency appears to impair the metabolism of the dietary mineral, iron, which is essential to the production of hemoglobin and red blood cells. Alleviating riboflavin deficiency in people who are deficient in both riboflavin and iron improves the effectiveness of iron supplementation for treating iron-deficiency anemia. Synthesis
Biosynthesis
Biosynthesis takes place in bacteria, fungi and plants, but not animals.