Previous studies have shown that high concentrations of omega-3 fatty acids have been found in the eye’s retina and that the nutrient could help to prevent vision damage. Now, a new investigation further suggests that omega-3s may help to protect against age-related macular degeneration (AMD).

According to the Centers for Disease Control and Prevention (CDC), AMD damages a person’s central vision which affects the retina.

The researchers studied the amount of fish and shellfish – rich in omega-3s – that more than 2,300 participants consumed over one year. All of the subjects were between 65 and 84 years old and completed an assessment that categorized them into four groups. These included no AMD, early AMD, intermediate-stage and advanced AMD.

Sheila K. West, PhD, the study’s lead researcher, said that overall, the results “[corrorborate] earlier findings that eating omega-3-rich fish and shellfish may protect against advanced AMD.” She added that although all of the participants ate an average of one serving of fish or shellfish per week, those who were in the advanced stage of this disease were much “less likely to consume high omega-3 fish and seafood” compared to all of the other participants.

The CDC reports that nearly 2 million Americans who are at least 40 years old suffer from AMD.