Objective: To compare pretrabeculectomy and posttrabeculectomy progression rates in normal-tension glaucoma in 6 subfields of the central 30 visual field.

Methods: A retrospective study. Methods: Clinical records of 34 patients with normal-tension glaucoma (12 males and 22 females) with progressive visual field loss undergoing successful trabeculectomy were studied. The time course of the mean deviation (MD) and mean of total deviation in the superior/inferior arcuate, paracentral, and cecocentral subfields were analyzed using a linear mixed-effects model.

Results: Patients' age, intraocular pressure (IOP), MD, and pretrabeculectomy and posttrabeculectomy follow-up averaged 57.7 ± 9.6 years, 15.7 ± 1.7 mm Hg, -12.7 ± 5.5 dB, and 4.6 ± 1.5 and 5.7 ± 1.2 years, respectively. Average IOP was lowered by 6.1 ± 3.3 to 10.3 ± 2.7 mm Hg (5-14 mm Hg) over the postoprerative period with MD change rate of -0.25 dB/y (P < 0.003), which was slower (P < 0.001) than the preoperative one (-0.70 dB/y). The preoperative mean of total deviation change rate (-0.31 to -1.35 dB/y) improved postoperatively in the superior and inferior paracentral subfields (P < 0.001), whereas it remained unchanged in the inferior cecocentral/arcuate subfields (P > 0.10). The postoperative rate of progression showed no significant variation in these subfields.

Conclusions: The rate of progression significantly varied among the 6 subfields preoperatively. It was significantly slowed down in the superior subfields by surgical IOP reduction, but not in the inferior cecocentral/arcuate subfields.