Selective Laser Trabeculoplasty (SLT): Predictors of Failure

Abstract

PURPOSE. SLT is widely used to control intraocular pressure (IOP) in glaucoma. We wished to determine predictive factors for long term success of SLT performed by full time faculty at a University Eye Clinic in Dallas. METHODS. Charts of patients with primary open angle glaucoma who underwent SLT between 2001 and 2011 were reviewed retrospectively. Those with follow up < 3 months, prior ALT/SLT, filtering procedure or inadequate data were excluded. The dependent variable was time to failure after SLT. Failure was defined as any additional medication, ALT/SLT, or glaucoma filtering surgery. All patients were treated with 360° SLT. Logistic regression and receiver operating characteristic (ROC) analysis was performed to assess correlation between time to failure after SLT and age, pre-op IOP, C/D ratio, visual field defect (VFD), family history of glaucoma, refractive error, hypertension, diabetes, number of medications, laser energy used, central corneal thickness. Results. Evaluable data was obtained on 189 patients; mean age 64, 44% male, 56% female, 49% white, 32% black, 12% Hispanic and 7 % others. 29.6% (56/189) were classified as SLT failures. Failure and non-failure patients had equal follow-up duration of median 2 yr. Age and laser energy were not significant predictors of SLT. In multivariable logistic regression models, statistically significant risk factors associated with SLT failure were family history of glaucoma (odds ratio (OR) = 1.7, 95% CI: 1.1-2.7, p=0.02), higher pre-op IOP (OR =1.1, 95%CI: 1.0-1.15, p=0.03), and moderate to severe VFD (OR =2.6, 95% CI: 1.3-5.2, p=0.006); ROC AUC = 0.71 (95% CI : 0.62-0.80). CONCLUSIONS. SLT results were better in patients without family history of glaucoma and who had lower pre-op IOP and mild to moderate visual field defects.