A.M. Bovell

Selective laser trabeculoplasty versus argon laser trabeculoplasty: results from a 1-year randomised clinical trial

Aims: To compare selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT), in terms of intraocular pressure (IOP) lowering, in patients with open-angle glaucoma. Methods: 176 eyes of 152 patients were enrolled in this study, 89 in the SLT and 87 in the ALT groups. Patients were randomised to receive either SLT or ALT treatment to 180° of the trabecular meshwork. Patients were followed up to 12 months after treatment. The main outcome measured was IOP lowering at 12 months after treatment, compared between the SLT and ALT groups. Results: No significant difference (p = 0.846) was found in mean decrease in IOP between the SLT (5.86 mm Hg) and ALT (6.04 mm Hg) groups at 1 year or at any other time points, nor were there any significant differences in the rate of early or late complications between the two groups. Conclusions: SLT is equivalent to ALT in terms of IOP lowering at 1 year, and is a safe and effective procedure for patients with open-angle glaucoma.

Baseline IOP predicts selective laser trabeculoplasty success at 1 year post-treatment: results from a randomised clinical trial

Background/aims: The efficacy and safety of selective laser trabeculoplasty (SLT) has been found to be equivalent to argon laser trabeculoplasty (ALT). Since SLT produces significantly less disturbance to the trabecular meshwork and is theoretically more repeatable than ALT, it has potential to replace ALT as the standard procedure to treat medically uncontrolled open angle glaucoma. This study’s objective is to determine factors that predict successful SLT at 1 year post-treatment. Methods: As part of a randomised clinical trial comparing the efficacy and safety of SLT to ALT, data on 72 SLT patients were collected, and successful SLT defined as having an SLT induced intraocular pressure (IOP) reduction of ⩾20% at 1 year post-treatment follow up. Results: 43 out of the 72 patients who had completed their 1 year follow up visit had an IOP reduction of ⩾20% from baseline. No glaucoma risk factors studied predicted successful SLT. The amount of trabecular meshwork pigmentation was not a significant predictor. However, it was discovered that baseline IOP strongly predicted SLT success (odds ratio = 1.16; p = 0.0001). Conclusion: SLT success was significantly predicted by baseline IOP but not by age, sex, other glaucoma risk factors, type of open angle glaucoma, or by degree of trabecular meshwork pigmentation.

Long term effects on the lowering of intraocular pressure: selective laser or argon laser trabeculoplasty?

OBJECTIVE Selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT) are used to lower intraocular pressure (IOP) in patients with open-angle glaucoma (OAG). We report long-term follow-up data comparing SLT to ALT. DESIGN Follow-up of prospective randomized clinical trial. PARTICIPANTS Patients with glaucoma from the practices of three ophthalmologists at the University of Ottawa. METHODS We randomized 176 eyes of 152 patients with uncontrolled IOP on maximal tolerated medical therapy (MTMT, with or without previous ALT) to undergo either SLT or ALT. Data were available for 142 eyes at 3 years, 134 eyes at 4 years, and 120 eyes at 5 years. The primary outcome was change in IOP from pretreatment baseline. RESULTS Comparison of baseline parameters was similar in the two groups. Lowering of IOP were similar at 3 years (SLT -6.7 ± 7.1 vs ALT -6.1 ± 5.1); at 4 years (SLT 7.0 ± 7.7 vs ALT -6.3 ± 5.0); and at 5 years (SLT -7.4 ± 7.3 vs ALT -6.7 ± 6.6). There was no statistically significant change in IOP in either of the two groups. Medication changes were equivalent in each group. A number of interventions were required in both groups, cumulatively, over the 5-year follow-up period (49 SLT and 33 ALT). Survival analysis indicated that the time to 50% failure in each group was approximately 2 years. CONCLUSIONS The IOP-lowering effect of SLT and ALT was similar over 5 years in this group of patients with open-angle glaucoma on MTMT.

Familial occurrence of pigment dispersion syndrome

BACKGROUND Pigment dispersion syndrome affects up to 4% of the white population. It is characterized by the presence of transillumination defects, Krukenbergs spindle and dense trabecular meshwork pigmentation. Open-angle glaucoma will develop in as many as 50% of affected patients. In this study we describe the familial occurrence of pigment dispersion syndrome in six North American pedigrees and the phenotypic characteristics with respect to pigment dispersion syndrome and glaucoma. METHODS Probands with pigment dispersion syndrome were identified in glaucoma clinics at university eye centres in Ottawa and Durham, NC. Families with two or more affected members were evaluated. All willing members in each family underwent a thorough clinical examination and were classified as affected with pigment dispersion syndrome, suspect or unaffected. The previous medical records were reviewed to obtain the past medical and ocular history, including risk factors for glaucoma. RESULTS All six families are white. Three families show at least two generations of affected members. Of the 43 subjects examined 58% were women. All 14 affected members showed moderate to heavy trabecular meshwork pigmentation and either Krukenbergs spindle or transillumination defects. The affected members were also considerably more myopic (mean spherical equivalent for the right eye -4.72 dioptres) than the suspect group or the unaffected group (mean spherical equivalent -0.79 D and +1.19 D respectively) (p < or = 0.001), and the intraocular pressure was higher for the affected than the unaffected group (mean for the right eye 20 mm Hg vs. 16 mm Hg) (p = 0.004). Half of those affected also had open-angle glaucoma. INTERPRETATION We have identified and phenotypically characterized six North American families with autosomal dominant pigment dispersion syndrome. Our ultimate goal is to identify the gene(s) that causes this disorder in order to clarify its molecular etiology and pathophysiology. This may give rise to a molecular classification of the disease as well as provide the foundation for genetic testing and new treatment approaches.