People who replace cigarettes with vaping or other non-combustible nicotine products may remain at a higher risk of developing serious eye diseases than those who quit nicotine altogether, according to a new South Korean study.

The research, conducted by Korea University College of Medicine, tracked 32,316 former smokers using South Korea’s National Health Insurance database for an average of 4.6 years.

Participants were divided into two groups: those who completely stopped using nicotine and those who switched to alternative nicotine products, including e-cigarettes.

During the follow-up period, researchers identified 6,328 new cases of eye disease. The incidence rate was 41.1 cases per 1,000 person-years among participants who quit nicotine completely, compared with 44 cases per 1,000 person-years among those using nicotine alternatives.

After adjusting for other factors, researchers found that users of alternative nicotine products had a 7% higher overall risk of developing eye diseases.

The greatest increase was seen in diabetic retinopathy, with the risk 24% higher among users of nicotine alternatives. Researchers also found an elevated risk of disorders affecting the eye’s focusing ability.

The findings were published in the American Journal of Ophthalmology.

The researchers said the results suggest that switching from cigarettes to vaping or other nicotine alternatives may reduce exposure to smoke but does not eliminate the risk of eye disease. They concluded that completely quitting nicotine may provide greater protection for long-term eye health.