Laser trabeculoplasty: an investigation into factors that might influence outcomes

Objective

To examine the effectiveness of argon (ALT) or selective (SLT) laser trabeculoplasty (LTP) in lowering intraocular pressure (IOP) and to determine whether patient-related factors had any impact on outcome.

Design

Retrospective review.

Participants

500 patients treated with LTP over 14 years.

Methods

This study was conducted at Sunnybrook Health Sciences Centre, University of Toronto. Five patient-related characteristics were used as dependent variables—age, race, gender, pseudophakic status, and pseudoexfoliation. IOP decrease and treatment failure at 12 months were the main outcome variables.

Results

500 eyes of 500 patients were included, 350 after ALT and 150 after SLT. The mean ± standard deviation baseline IOP was significantly higher in the patients treated by ALT than in those treated by SLT (24.2 ± 5.4 versus 22.2 ± 4.6, p < 0.0001) at baseline but not at 1 year (19.6 ± 5.1 versus 19.5 ± 6.1, p = 0.41). When the final IOP was examined by multiple regression analysis, there was a significant effect in favor of ALT over SLT (p = 0.03) and for patients with higher baseline IOPs (p < 0.0001). No significant effect was found for any of the demographic subgroupings. However, when the outcome variable was success or failure, only the baseline IOP remained significant.

Conclusions

Specific patient characteristics do not significantly influence LTP outcome after 12 months of follow-up. The most powerful predictor of either final IOP or clinical success was a higher baseline IOP, but ALT may have a better ability to lower IOP.