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Original Investigation
March 5, 2020

Effects of Cataract Surgery on Melatonin Secretion in Adults 60 Years and Older: A Randomized Clinical Trial

Author Affiliations
  • 1Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan
  • 2Department of Epidemiology, Nara Medical University School of Medicine, Nara, Japan
JAMA Ophthalmol. 2020;138(4):405-411. doi:10.1001/jamaophthalmol.2020.0206
Key Points

Question  Does cataract surgery affect melatonin secretion in patients aged 60 years and older undergoing their first cataract surgery?

Findings  In this randomized clinical trial, 169 patients with cataracts were randomized to receive prompt cataract surgery with a clear or yellow artificial intraocular lens or delayed surgery with a clear or yellow intraocular lens. Urinary melatonin excretion values were significantly higher in the cataract surgery group at 3 months after the operation than the control group.

Meaning  The results of this study suggest that increased light perception by cataract surgery may align the internal biological rhythm with the external environment accompanied by increased melatonin secretion.

Abstract

Importance  Cataract surgery, which increases perception of light, may increase melatonin secretion. Melatonin secretion has been associated with depression, diabetes, cognitive impairment, and breast cancer. To date, no evidence from a randomized clinical trial exists to support this cataract surgery hypothesis.

Objective  To determine whether cataract surgery modifies the melatonin secretion at 3 months after cataract surgery in 169 adult patients.

Design, Setting, and Participants  A parallel-group randomized clinical trial was conducted at a single referral center from July 1, 2014, to June 30, 2017. Data were analyzed from January 1, 2018, to March 31, 2019. Patients were aged 60 years or older, had no history of cataract surgery, and had cataracts with grade 2 or higher nuclear opacifications based on the Lens Opacities Classification System III. Analyses were based on intention to treat.

Interventions  Patients were randomized 1:1:1:1 to receive cataract surgery using artificial clear intraocular lens (IOL) or yellow IOL. Group 1 received prompt surgery with clear IOL, group 2, prompt surgery with yellow IOL, group 3, delayed surgery with clear IOL, and group 4, delayed surgery with yellow IOL. The intervention group consisted of groups 1 and 2, and the control group consisted of groups 3 and 4.

Main Outcomes and Measures  Urinary melatonin excretion in the intervention group was measured at 3 months after surgery, and urinary melatonin excretion in the control group was measured before delayed surgery.

Results  Of the 169 randomized patients, 97 were men (57.4%). The mean (SD) age was 75.7 (6.7) years. Mean urinary melatonin excretion was calculated as standardized urinary concentration, the ratio of urinary concentration to urinary creatinine concentration (nanograms per milligram of creatinine), in the intervention group after cataract surgery. Mean urinary melatonin excretion was significantly higher than in the control group (adjusted mean difference of creatinine concentration, 0.159 log ng/mg, 95% CI, 0.045-0.273; P = .007) independent of baseline urinary melatonin excretion and potential confounders. Subgroup analysis comparing group 1 with group 3 revealed that concentration of urinary melatonin excretion in patients who received clear IOLs was higher than the control group by creatinine concentration 0.212 log ng/mg (95% CI of the difference, 0.058-0.365; P = .008). However, the difference between patients in group 2 and group 4 was not significant (adjusted mean difference for creatinine excretion, 0.083 log ng/mg, 95% CI, –0.087 to 0.253; P = .33). The difference of concentration of mean urinary melatonin excretion between patients in group 1 and those in group 2 was not significant (95% CI of the difference for creatinine concentration, –0.19 to 0.40 log ng/mg; P = .48).

Conclusions and Relevance  The findings in this study support the hypothesis that cataract surgery increases melatonin secretion. The effect of clear IOLs vs yellow IOLs on these outcomes was not shown to be different.

Trial Registration  UMIN-CTR Identifier: UMIN000014559

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