Target intraocular pressure for stability of visual field loss progression in normal-tension glaucoma

To determine the target intraocular pressure (IOP) level in normal-tension glaucoma (NTG) for visual field (VF) stability following trabeculectomy. Forty eyes of 40 patients who underwent trabeculectomy were enrolled in this study. Progression was determined by a decrease in the Advanced Glaucoma Intervention Study VF defect score of four or more points. The Kaplan-Meier life table method was employed to compare the postoperative VF stability with predetermined IOP levels. The mean postoperative follow-up period was 12 years. At the final visit, the IOP was reduced from 15.2 to 9.4 mmHg on average (P < 0.0001). Reductions in IOP of 20% from baseline were achieved in 70.0% of eyes. The cumulative probability of VF stability was 92.7% in patients having an IOP reduction of > 20%, whereas all patients in the poorly controlled IOP group showed progression (P < 0.0001). When IOP values of 9, 10, 11, and 12 mmHg were employed as the cutoff, the best VF prognosis was attained in eyes with a postoperative IOP of 10 mmHg. An IOP reduction of at least 20% from baseline or IOP a parts per thousand currency sign10 mmHg is recommended as the target postoperative IOP in progressive NTG.