COMPARATIVE EFFECT OF GLYCERIN AND GREEN TEA ON INTRAOCULAR PRESSURE AMONG HEALTHY ADULTS: A COMPARATIVE CROSS-SECTIONAL STUDY

Abstract

Background: Intraocular pressure (IOP) is the only modifiable risk factor for glaucoma and plays a vital role in maintaining ocular health. Both glycerin and green tea have been reported to reduce IOP through different mechanisms; however, direct comparison of their effects remains limited.

Objective: To compare the effect of oral glycerin and green tea on intraocular pressure among healthy adults.

Methodology: A comparative cross-sectional study was conducted at the Department of Ophthalmology, University of Lahore Teaching Hospital, Lahore, from March to June 2026. A total of 120 healthy participants aged 25–35 years were enrolled through non-probability purposive sampling and equally allocated into glycerin (n=60) and green tea (n=60) groups. Baseline IOP was measured using a non-contact tonometer. Participants in the green tea group received 200 mL of freshly brewed green tea, while those in the glycerin group received oral glycerin (1–1.5 g/kg body weight). IOP was recorded at baseline, 60 minutes, and 120 minutes after intervention. Data were analyzed using SPSS version 27. Friedman and Wilcoxon signed-rank tests were applied, with p<0.05 considered statistically significant.

Results: Both interventions significantly reduced intraocular pressure (p<0.001). Glycerin produced a rapid and greater reduction in IOP at 60 minutes, followed by a partial rebound at 120 minutes. In contrast, green tea demonstrated a gradual and sustained reduction in IOP throughout the observation period. The pattern of IOP reduction was statistically significant in both right and left eyes.

Conclusion: Both glycerin and green tea effectively reduced intraocular pressure. Glycerin showed a stronger short-term ocular hypotensive effect, whereas green tea produced a more sustained reduction over time. These findings suggest that glycerin may be useful for rapid IOP reduction, while green tea may serve as a supportive natural intervention for maintaining ocular health.