Abstract
PURPOSE: To determine the cost (loss of visual function associated with the procedure) and benefit (long-term preservation of the visual field) of glaucoma surgery. METHODS: We included 100 patients who underwent glaucoma surgery (Baerveldt glaucoma implant [BGI], n = 61; trabeculectomy [TE], n = 39). Preoperatively, the median (interquartile range [IQR]) standard automated perimetry mean deviation (MD) was -12 (-16 to -6) dB. We analysed the change in visual acuity (BCVA) and MD due to the procedure and, in a subset with at least 5 years of perimetric follow-up both pre- and postoperatively (n = 20), the change in rate of progression (ROP; time rate of change in MD). For the surgery-induced change in ROP, we also performed a meta-analysis including the current and previously published studies. From the surgery-induced decrease in MD and change in ROP, we calculated the average postoperative duration needed for the benefit to surpass the cost. RESULTS: Mean (standard deviation) MD decline was 1.3 (2.7) and 1.0 (2.3) dB for BGI (p < 0.001) and TE (p = 0.009), respectively; no significant surgery-induced changes in BCVA were found (p = 0.08 and p = 0.12, respectively). In our study, surgery was associated with a non-significant deceleration of ROP (from -0.37 [0.52] to -0.15 [0.48] dB/year; p = 0.23). The meta-analysis, based on eight studies, showed an overall surgery-induced change in ROP of 0.44 (95% confidence interval 0.25 to 0.64; p < 0.0001) dB/year. CONCLUSION: Glaucoma surgery significantly reduces the progression velocity in glaucoma. On average, the benefit of glaucoma surgery surpasses the cost after approximately 1.5 years.