Selective laser trabeculoplasty reduces mean IOP and IOP variation in normal tension glaucoma patients

Abstract

Purpose: To evaluate the effect of selective laser trabeculoplasty (SLT) in normal tension glaucoma (NTG) patients.

Patients and methods: A retrospective review was performed of NTG patients who had undergone SLT at the Duke University Eye Center between 12/2002 and 7/2005. For each eye of each patient at pre-laser and post-laser time points, the IOP measurements were summarized by mean, standard deviation, and range. Then for each of these descriptive statistics, the differences between pre-laser and post-laser values were obtained. Statistical analysis was performed using a random effects model.

Main outcome measures: difference in mean IOP, standard deviation of IOP, and range of IOP.

Results: Thirty-one eyes of 18 patients were included for analysis. The average of the mean pre-operative IOP measurements was 14.3 +/- 2.6 mmHg compared to 12.2 +/- 1.7 mmHg (P < 0.001) post-operatively. The mean pre-operative standard deviation was 1.9 +/- 0.9 mmHg compared to 1.0 +/- 0.6 mmHg (P = 0.002) post-operatively while the mean IOP range prior to treatment was 4.5 +/- 2.5 mmHg compared to 2.5 +/- 1.9 mmHg (P = 0.017) after treatment.

Conclusion: In this pilot study, SLT was found to lower mean IOP and intervisit IOP variation in NTG patients. Given the importance of IOP variation and its association with glaucoma progression, measurement of IOP variation following treatment with SLT may be considered.

Keywords: NTG; SLT; glaucoma; laser.

Figure 1

Boxplot of mean IOP pre-SLT vs post-SLT in NTG patients.

Figure 2

Boxplot of standard deviation pre-SLT vs post-SLT in NTG patients.

Figure 3

Boxplot of range of IOP pre-SLT and post-SLT in NTG patients.