Fornix-Based versus Limbus-Based Conjunctival Flap in Trabeculectomy: A Quantitative Evaluation of the Evidence

Abstract

ObjectiveTo evaluate the efficacy and tolerability of limbus-based (LBCF) compared with fornix-based conjunctival flaps (FBCF) for trabeculectomy in the treatment of patients with uncontrolled glaucoma.MethodsA comprehensive literature meta-analysis was performed according to the Cochrane Collaboration methodology to identify controlled clinical trials comparing LBCF with FBCF in trabeculectomy. The efficacy measures were the weighted mean differences (WMDs) for intraocular pressure reduction (IOPR), the reduction in glaucoma medications, and the relative risks (RRs) for success rates. Tolerability estimates were measured by RR for adverse events. The pooled effects were calculated using the random effects model.ResultsSixteen controlled clinical trials meeting the predefined criteria were included in the meta-analysis. A total of 1,825 eyes from 1,392 patients with medically uncontrolled glaucoma were included. The WMD of the IOPR from baseline was 1.12 (95% CI: −0.88 to 3.12) when comparing LBCF with FBCF. LBCF was associated with numerically greater but non-significant IOP lowering efficacy than FBCF (P = 0.270). LBCF was comparable with FBCF in the reduction of glaucoma medication, with a WMD of 0.15 (−0.05 to 0.36) at the follow-up endpoint (P = 0.141). The pooled RR comparing LBCF with FBCF were 1.08 (0.94, 1.23) for the complete success rate and 1.01 (0.92, 1.10) for the qualified success rate. Rates of adverse events did not differ significantly between LBCF and FBCF.ConclusionsThere is no significant difference in IOP lowering, number of glaucoma medications, or proportion of patients who reached the IOP target between LBCF and FBCF trabeculectomy. Both incision techniques may contribute equally to adverse events.

The impact of conjunctival flap method and drainage cannula diameter on bleb survival in the rabbit model

“…Our study showed that conjunctival flap method did not have a significant impact on bleb survival in the rabbit model. The results of our study fall in line with previous retrospective human studies [ 6 , 18 – 20 ] which showed no major differences in efficacy between the two methods. It appears that surgical skill and preference are the main factors that should determine conjunctival flap approach in the rabbit model.…”

The Ahmed shunt versus the Baerveldt shunt for refractory glaucoma: a meta-analysis

“…The authors’ reported means and standard deviations (SD) of the IOPR were directly used. When these were not available, they were computed as follows: IOPR = IOP baseline - IOP endpoint , SD IOPR = (SD baseline 2 + SD endpoint 2 - SD baseline × SD endpoint ) 1/2 [ 19 ]. The secondary outcome measure was the difference in reduction between glaucoma medications.…”

Limbus- Versus Fornix-Based Trabeculectomy for Open-Angle Glaucoma Eyes with Prior Ocular Surgery: The Collaborative Bleb-Related Infection Incidence and Treatment Study

“…In a previous meta-analysis report about limbus- and fornix-based trabeculectomies, IOP reduction appeared to be the same or superior in limbus-based trabeculectomy 13 . If the difference of the rates of surgical failure was 20%, the minimum sample size was calculated to be 151 eyes with a one-sided significance level of 0.05 and a power of 0.8.…”

“…By contrast, avascular and cystic blebs created by limbus-based trabeculectomy procedures may contribute to the surgical outcome in these cases. Although there are many retrospective and prospective studies about the comparison of surgical outcomes between limbus- versus fornix-based trabeculectomy, most of the studies have not shown significant better surgical outcomes with limbus-based trabeculectomy than fornix-based trabeculectomy 13 14 15 16 17 18 19 20 21 22 23 24 . This may be due to the small sample size or the use of patients with various backgrounds that comprised low and high risk factors.…”