COMPARATIVE STUDY OF THE EFFICACY OF SELECTIVE LASER TRABECULOPLASTY FOR PSEUDOEXFOLIATION GLAUCOMA AND PRIMARY OPEN-ANGLE GLAUCOMA

Background. To compare the efficacy of selective laser trabeculoplasty (SLT) as treatment of pseudoexfoliation glaucoma (PG) and primary open-angle glaucoma (POAG) in a prospective clinical study.Methods. Ten eyes of 10 patients suffering from uncontrolled PG (PG group) and 10 eyes of 10 patients with uncontrolled POAG (POAG group) were treated with a frequency-doubled, Q-switched Nd:YAG laser (532 nm). The baseline characteristics were similar in both groups. The intraocular pressure (IOP) was measured before the treatment and 1day, 1 week, 1 month and 3, 6, 9, 12, 15, 18, 24, 30, and 36 months after the treatment. Success was defined as an IOP lowering, exceeding 20% of pretreatment IOP. Any modification of hypotensive medication led to exclude the eye from the study. Statistical analysis comparing the two groups was carried out using the independent-sample t test for continuous variables and the Log-Rank test for survival analysis. All tests were conducted considering p< 0.05 as significant.Results. The mean follow-up time was 22.8 months (SD 12.5) for the PG group and 24.3 months (SD 10.8) for the POAG group (n. s.). No significant difference was found between the two groups for mean pretreatment IOP (23.6 mm Hg [SD 5.7] in the PG group vs. 22.8 mm Hg [SD 2.4] in the POAG group) and for mean IOPs during the whole follow-up period. At all follow-up visits, the mean IOP reductions were smaller in the PG group than in the POAG group (7.0 mm Hg [SD 3.3] vs. 7.7 mm Hg [SD 2.0] at 24 months). However such difference was statistically signifficant only at 36 months (4.7 mm Hg [SD 1.1] vs. 8.3 mm Hg [SD 1.5]). At all follow-up visits, the mean percent IOP reduction was smaller in the PG group than in the POAG group (27.6% [SD 7.1] vs. 32.1% [SD 7.1] at 24 months). Furthermore, such a difference was statistically significant at 9, 12, and 36 months (21.8% [SD 1.6] vs. 34.1% [SD 4.7]). According to the Kaplan-Meier survival analysis, the 36-month success rate was 47% in the PG group and 59% in the POAG group, but the differences between the two groups were nonsignificant (p> 0.05).Conclusions. SLT is an effective procedure for lowering IOP, although within 3 years there has been a substantial failure rate in both PG and POAG eyes, and the success seems to decline faster in PG eyes.