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

Mohammed K El Mallah¹, Molly M Walsh², Sandra S Stinnett², Sanjay G Asrani^2
1Ocala Eye, Ocala, Florida, USA; ²Duke University Eye Center, Durham, North Carolina, USA

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: SLT, NTG, laser, glaucoma