Comparison of intraocular pressure fluctuation before and after cataract surgeries in normal-tension glaucoma patients

Purpose: Cataract surgeries have been shown to reduce intraocular pressure. We used a Sensimed Triggerfish (R) contact lens sensor to compare intraocular pressure levels and their fluctuation between before and after cataract surgeries in patients with normal-tension glaucoma. Methods: This was a prospective open-label study. Thirteen patients with normal-tension glaucoma were included. All patients underwent a 1-month washout and discontinued glaucoma medications during this study. In each eye, intraocular pressure fluctuations over 24 h were measured with the contact lens sensor before and at 3 months after the cataract surgery. We compared intraocular pressure levels and their fluctuation between before and after cataract surgeries. We used two approaches to evaluate the amplitude of intraocular pressure fluctuations: dual-harmonic regression analysis, and measurement of the difference between the maximum and the minimum value. Results: The mean pre-operative intraocular pressure was 14.7 +/- 2.2 mm Hg and mean post-operative intraocular pressure was 11.4 +/- 2.2 mm Hg. Cataract surgery significantly decreased intraocular pressure (p = 0.0005). In both methods, the post-operative fluctuations in intraocular pressure over 24 h were significantly smaller than their pre-operative counterparts (dual-harmonic regression analysis: p = 0.0171; difference between the maximum and the minimum: p = 0.0398). Conclusion: Cataract surgery decreased both intraocular pressure values and intraocular pressure fluctuations in normal-tension glaucoma patients.