The acute effect of a single dose of green tea on the quality and quantity of tears in normal eye subjects
Received 10 January 2019
Accepted for publication 22 February 2019
Published 10 April 2019 Volume 2019:13 Pages 605—610
Checked for plagiarism Yes
Review by Single-blind
Peer reviewer comments 3
Editor who approved publication: Dr Scott Fraser
Ali M Masmali, Saud A Alanazi, Abdullah G Alotaibi, Raied Fagehi, Ali Abusharaha, Gamal A El-Hiti
Cornea Research Chair, Department of Optometry, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
Objective: The study aimed to investigate the acute effect of a single dose of green tea on the quality and quantity of tears in normal eye subjects.
Methods: Forty normal eye subjects (22 men and 18 women) aged 19–39 years were enrolled in the study. Also, an age matching control group (20 males and 20 females) was enrolled for comparison. McMonnies dry eye symptoms questionnaire and slit lamp were used for the exclusion criteria determination. Phenol red thread (PRT) test was performed on both eyes of each subject. A tear sample was collected from the lower tear meniscus of the right eye of each subject for the tear ferning (TF) test, which was performed before (30 minutes) and after (60 minutes) drinking green tea.
Results: The median PRT measurement after green tea consumption was lower (median [IQR]=23.50 [8.00] mm) compared to that before consumption (median [IQR]=27.00 [8.75] mm). In contrast, the median TF grade was significantly higher following green tea consumption than that before consumption (median [IQR]=2.65 [1.23] vs 1.50 [0.88] mm, respectively). The results show that TF grades increased in 97.5%, and the red phenol thread scores decreased in 80% of the subjects after green tea consumption compared to those before consumption. The PRT readings and TF grades were significantly different (P<0.05) before and after green tea consumption.
Conclusion: Drinking green tea could have a significant effect on the eye tear film quality. Tear quality appeared to decrease after green tea consumption.
Keywords: dry eye, tear ferning test, green tea, phenol red thread test, tear film, polyphenols
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