To evaluate circulatory melatonin levels by assessing nocturnal urinary excretion of 6-sulfatoxymelatonin (aMT6s) in patients with primary open-angle glaucoma (POAG) and to compare the high-tension group and the low-tension group.
This study included 80 eyes of 41 POAG patients and 87 eyes of 44 control subjects. POAG group was further classified into high-tension group and low-tension group according to the pretreatment intraocular pressure (IOP). The first urine in the morning was collected and aMT6s were measured using a commercial ELISA kit. Urinary aMT6s levels were expressed as ng aMT6s/mg creatinine. Differences in melatonin levels among the control and POAG subgroups were evaluated by generalized estimating equation adjusting age, sex, sleep duration, and intereye correlation.
Urinary aMT6s/creatinine ratio did not differ between POAG and control group (P=0.097). The difference in the aMT6s/creatinine ratio between the 3 groups—high-tension group with baseline IOP≥21 mm Hg (19.74±3.12 ng/mg), low-tension glaucoma group with baseline IOP<21 mm Hg (26.71±3.47 ng/mg), and control group (30.35±3.05 ng/mg)—was statistically significant (P=0.046). Post hoc analysis revealed that the difference between the control and high-tension glaucoma groups was significant (P=0.014), whereas the difference between the control and low-tension glaucoma groups was not (P=0.436).
This study found low melatonin levels in high-tension glaucoma compared with the control.
Inha Vision Science Laboratory, Department of Ophthalmology, Inha University School of Medicine, Incheon, Korea
J.Y.K. and A.R.J. contributed equally.
Presented at the 112th Annual Meeting of the Korean Ophthalmological Society 2014.
Supported by an Inha University Hospital Research Grant.
Disclosure: The authors declare no conflict of interest.
Reprints: Na Rae Kim, MD, PhD, Department of Ophthalmology, Inha University Hospital, 27, Inhang-ro, Jung-gu, Incheon 22332, Republic of Korea (e-mail: firstname.lastname@example.org).
Received February 23, 2018
Accepted October 13, 2018