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Br J Ophthalmol. 2018 Nov 15. pii: bjophthalmol-2018-312257. doi: 10.1136/bjophthalmol-2018-312257. [Epub ahead of print]

Genetic variants in a sodium-dependent vitamin C transporter gene and age-related cataract.

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Cataract Services, Aravind Eye Hospital, Madurai, India.
Department of Genetics, Dr.G.Venkataswamy Eye Research Institute, Aravind Medical Research Foundation, Madurai, India.
Cataract Services, Aravind Eye Hospital, Pondicherry, India.
Community Ophthalmology Department, Dr.Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, Delhi, India.
Dipartimento di Scienze Otorino-Odonto-Oftalmologiche e Cervico Facciali, Universita` degli Studi di Parma, Parma, Italy.
Centre for Public Health, Queen's University Belfast, Belfast, UK.
Faculty of Epidemiology & Population Health, London School of Hygiene & Tropical Medicine, London, UK.
Faculty of Epidemiology & Population Health, London School of Hygiene & Tropical Medicine, London, UK



Cataract is a major health burden in many countries and a significant problem in India. While observational studies show lower cataract risk with increasing dietary or plasma vitamin C, randomised controlled trials of supplements have been negative. Genetic variants in vitamin C transporter proteins (SLC23A1), especially rs33972313, may provide evidence on a causal association of vitamin C with cataract.


We used data from a randomly selected population-based study in people aged 60 years and above in north and south India. Of 7518 sampled, 5428 (72%) were interviewed for socioeconomic and lifestyle factors, attended hospital for lens imaging and blood collection and were subsequently genotyped for rs33972313 and rs6596473. Mixed or pure types of cataract were graded by the Lens Opacity Classification System III as nuclear (2404), cortical (494) or posterior subcapsular cataract (PSC) (1026); 1462 had no significant cataract and no history of cataract surgery and 775 had bilateral aphakia/pseudophakia.


rs33972313 was associated with cortical (OR 2.16; 95% CI 1.34 to 3.49, p=0.002) and PSC (OR 1.68; 95% CI 1.06 to 2.65, p=0.03) but not with nuclear cataract. In analyses of pure cataracts, associations were found only between rs33972313 and pure cortical cataracts (OR 2.29; 95% CI 1.12 to 4.65, p=0.03) ‚ÄČand with a standardised cortical opacity score. There was no association with rs6596473 and any cataract outcomes.


Using an established genetic variant as a proxy for lifetime ascorbate concentrations, our results support a causal association of vitamin C with cataract.


ascorbate; epidemiology; genetics; lens and zonules

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