Spontaneous Intraocular Pressure Reduction in Normal-Tension Glaucoma and Associated Clinical Factors

Abstract

To investigate the intraocular pressure (IOP) reduction in certain normal-tension glaucoma (NTG) patients and clinical factors associated with this reduction. Methods: Fifty-four NTG patients who met the following enrollment criteria were selected: IOP <21 mm Hg during a 24-hour pressure curve and throughout the subsequent 12 months; examined every 1 to 4 months for at least 3 years with no ocular hypotensive therapy. For each patient, the eye with the higher mean IOP during the 24-hour pressure curve was selected for this study. Results: Six patients had an IOP reduction which was defined as a significant decrease ( P < .05) of IOP over time, determined by the Spearman rank correlation coefficient method. These 6 eyes were rated positive for subsequent IOP reduction. The IOP reduction was correlated to clinical factors by means of a logistic multiple regression analysis (LOGIST procedure using PC-SAS), which demonstrated that the larger difference between the maximum IOP and the minimum IOP during the initial 24-hour pressure curve and the absence of disc hemorrhage showed significant correlation with IOP reduction ( P = .026 and P = .013, respectively). The odds ratios were 2.05 per 1 mm Hg increase of difference between the maximum IOP and the minimum IOP during the initial 24-hour pressure curve and 1.13 for the absence of disc hemorrhage. Conclusions: The current study demonstrated that a significant reduction of IOP over time is not uncommon in NTG patients. One ninth of the NTG patients in this study showed a significant IOP reduction during a 3-year follow-up period.