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T.A. Labbe, A. Singh; Factors Associated With Intraocular Pressure Lowering After Selective Laser Trabeculoplasty . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5460.
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To determine if intraocular pressure lowering after Selective Laser Trabeculoplasty (SLT) can be correlated with clinical or demographic variables of glaucoma patients.
We performed a retrospective chart review of 20 consecutive patients who had Selective Laser Trabeculoplasty (SLT) performed by one glaucoma specialist. Follow–up ranged from 3 months to 18 months. Demographic and clinical information including age, race, maximum intraocular pressure, cup to disc ratio, central corneal thickness, angle width and iris insertion using the Spaeth gonioscopic grading system, pigmentation of the angle, and presence of an intraocular lens was recorded. In all patients, SLT was performed only after the patient was on maximal tolerated medical therapy. Pressure lowering medications were continued after the procedure. The difference between average intraocular pressure (IOP) before and after SLT was determined. Goldman applanation was used to measure IOP. Pearson’s correlation coefficient was then used to determine which clinical information correlated with a decrease in eye pressure after SLT.
The average decrease in IOP after SLT was 2.7 mm Hg with a standard deviation of +/– 3.2 mm Hg. The decrease in IOP after SLT ranged from 1 mm Hg to 13 mm Hg. We found that 75% of patients had a decrease in IOP after SLT. Over 60% of patients had at least a 2 mm decrease in IOP after SLT. Age, history of a previous cataract extraction, degree of pigmentation of the angle, number of glaucoma medications used prior to surgery, and being of African American origin all had low Pearson correlation coefficients of less than 0.1. On the other hand, there was a stronger Pearson’s correlation between the change in intraocular pressure and gonioscopic angle width (0.33), maximal recorded IOP (0.41), and central corneal thickness (0.19). A negative Pearson’s correlation of –0.49 existed between cup to disc ratio and average pressure change.
Our results suggest that patients with thicker corneas, higher pre–laser IOP, and wider angle widths may have the best IOP reductions after SLT. Advanced disease may decrease the effectiveness of SLT because high cup to disc ratio was negatively correlated with IOP reduction after SLT. On the other hand, we were unable to show a significant correlation between IOP lowering of SLT and age, history of a previous cataract extraction, degree of pigmentation of angle, number of glaucoma medications used prior to surgery, and being of African American origin.
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