Researchers based at Brigham and Women's Hospital and Harvard Medical School conducted a randomised, double-blind study from 1997 to 2011 of 14,641 US male doctors aged 50 and older.
Half took a common daily multivitamin, as well as vitamin C, vitamin E and beta carotene supplements. The other half took a placebo.
The researchers followed the participants to identify how many participants in each group developed new cases of two common eye diseases: cataract, which is a clouding of the eye's lens, and age-related macular degeneration (AMD), the deterioration of the eye's macula that is responsible for the ability to see fine details clearly.
The researchers found that in the placebo group 945 cases of cataract developed, which were self-reported and confirmed by medical records, while only 872 cases of cataract developed in the multivitamin group, representing a 9 per cent decrease in risk.
This risk was even lower, at 13 per cent, for nuclear cataract, which occurs at the centre of the lens and is the most common variety of cataract associated with the ageing process.
"If multivitamins really do reduce the risk of cataract, even by a modest 10 per cent, this rather small reduction would nonetheless have a large public health impact," said William Christen, the study's lead author and researcher from Harvard Medical School.
In terms of AMD risk, the researchers found there were 152 new cases of visually significant AMD in the multivitamin group compared to 129 in the placebo group, but the difference was not statistically significant.
"This finding of more cases of AMD in the multivitamin group than in the placebo group, although not statistically significant, does raise some concerns," said Christen.
"Clearly, this finding needs to be examined further in other trials of multivitamin supplements in both men and women," Christen added.
The study was published in Ophthalmology, the journal of the American Academy of Ophthalmology.