Effect of Cataract Surgery on Melatonin Secretion in Adults Aged 60 and Over
A study by ophthalmologists and epidemiologists from Nara University in Japan, recently published in JAMA Ophthalmology, examined the relationship between cataract surgery, the use of clear and yellow intraocular lenses, and the level of melatonin secretion.
Study Objectives
The perception of light by photosensitive retinal ganglion cells plays a significant role in synchronizing the circadian rhythm. Low concentrations of melatonin are associated with depression, diabetes, cognitive impairment, and breast cancer.
Cataract surgery, which leads to increased light perception, may affect melatonin secretion, but to date, there has been no randomized clinical trial to verify this hypothesis. The aim of the cited work was therefore to determine whether cataract surgery modifies melatonin secretion three months post-surgery in older adults.
Study Population
The study was conducted between July 2014 and June 2017. It included 169 patients, of whom 97 (57.4%) were men; their average age was 75.7 (SD 6.7) years. All enrolled patients were ≥ 60 years old, had not previously undergone any cataract surgery, and had cataracts classified as grade ≥ 2 according to the Lens Opacities Classification System III.
Methodology and Course of the Study
Patients were randomized in a 1:1:1:1 ratio. Group 1 had surgery at the earliest possible date and received a clear intraocular lens (IOL). Group 2 also had surgery without delay and received a yellow IOL. Group 3 had delayed surgery and received a clear IOL. In group 4, surgery was also delayed and a yellow IOL was implanted. The intervention group consisted of individuals from groups 1 and 2, whereas the control group consisted of participants from groups 3 and 4. Urinary melatonin excretion was measured in the intervention group three months after surgery, and in the control group before the delayed surgery.
Results and Conclusion
The average melatonin excretion in urine was significantly higher in the intervention group compared to the control group (p = 0.007). The difference between average urinary melatonin excretion between patients in groups 1 and 2 was not statistically significant (p = 0.48).
The results of this study thus support the hypothesis that cataract surgery leads to increased melatonin secretion, with no differences observed between the clear and yellow IOLs in this regard.
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Source: Nishi T., Saeki K., Miyata K. et al. Effects of cataract surgery on melatonin secretion in adults 60 years and older: a randomized clinical trial. JAMA Ophthalmol 2020 Mar 5, doi: 10.1001/jamaophthalmol.2020.0206 [Epub ahead of print].
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