A study conducted in Japan has found that cataract surgery increases melatonin secretion at three months post-op. Cataract surgery with intraocular lens (IOL) implantation may increase patients’ nonvisual light perception and improve their circadian alignment, which also increased the concentrations of melatonin secretion. Researchers have noted that this will combat low concentrations of melatonin secretion, which has been associated with depression, diabetes, cognitive impairment and breast cancer.

The study divided 169 adult patients (mean age of 75.7) into four groups: two intervention groups that consist of prompt surgery with either clear or yellow IOLs and two control groups of delayed surgery with either clear or yellow IOLs. At three months post-op, concentration of urinary melatonin excretion in patients who received clear IOLs was higher than the control group. However, the researchers found no significant difference in melatonin secretion between the two prompt surgery groups or between patients receiving clear or yellow IOLs.

While they believe further research is required to compare the effects of blue light-blocking IOLs, the researchers presume the effects of cataract surgery on melatonin secretion using blue light-blocking IOLs might be weaker because of reduced nonvisual light perception. Nevertheless, they report a beneficial effect of cataract surgery in the short-term.