Study results demonstrate lower IOP achievable with 360-degree versus 180-degree SLT
In addition to comparing the two techniques, Dr Shibata and colleagues also looked at the efficacy of SLT as an adjunct treatment of medically diagnosed openangle glaucoma. She noted, "Our results agreed with previous reports that SLT is effective in further lowering IOP in patients whose condition is uncontrolled by medical therapy."
A total of 54 patients were included in the study, 29 of whom were treated with 180degree SLT (35 eyes) and 25 of whom were treated with 360degree SLT (34 eyes). Followup of the patients was performed at 1 week, 1, 3, 6 months and then every 3 months thereafter. During each follow-up examination the team measured the patients' IOP and compared each of these measurements with the pretreatment IOP in each group. Additionally, the absolute IOP and percentage IOP reduction from baseline (the IOP reduction rate) were compared between the two groups.
"We investigated the relationship between the efficacy of SLT and patient characteristics, including pretreatment IOP, the number of pre-treatment glaucoma medications, age, glaucoma subtypes and total laser energy received," added Dr Shibata. "To compare long-term outcomes between the two groups, SLT success was defined as IOP reduction by 20% or more of pre-treatment IOP without additional medications, laser or surgery. The success rate was analysed by Kaplan-Meier survival analysis with a logrank test."
Results and discussion
"During the follow-up period, post-treatment IOP values after 360-degree SLT were significantly lower than pre-treatment level," said Dr Shibata. "Besides, the IOP reduction rate in 360-degree SLT remained significantly higher than that in 180-degree SLT." The team also noted that the lower the pretreatment IOP was, the lower the reduction rate became in 360degree SLT. Additionally, the Kaplan-Meier survival analysis demonstrated a higher success rate post 360degree SLT.
"The most surprising outcome was that IOP reduction rate in 360-degree SLT was greater than 20% until 9 months after SLT even though it was an adjunctive therapy. This may have significance for surgeons as some may choose to use 360degree SLT not only as initial therapy but also as an adjunctive therapy," concluded Dr Shibata.
Dr Maho Shibata is ophthalmologist at the Department of Ophthalmology, Osaka Medical College, Osaka, Japan and specializes in glaucoma and ocular blow flow (in particular optic nerve head blood flow). She may be reached by Email: email@example.com
Dr Shibata has indicated she has no financial interests in the subject matter.
1. M. Shibata et al., J. Glaucoma, 2012;21(1):17–21.