Comparison of PRESERFLO Implantation Techniques using a New Small Posterior Incision versus a Standard Anterior Peritomy

Purpose: To compare the standard implantation technique of a new ab externo microshunt (PRESERFLO) to a posterior technique with a small incision. The standard anterior approach (A) requires a relatively large, 6-8 mm perilimbal peritomy. In contrast, the posterior approach (P) involves only a 2-3 mm snip incision 2 mm posterior to the limbus. Methods: Charts of 126 PRESERFLO patients (54 A and 72 P) were retrospectively analyzed. Follow-up was 270 days. We compared the surgical time, intraocular pressure (IOP), number of medications, and complications. Results: The preoperative IOP in A was 21.8±8.5 mmHg and 23.9±8.1 mmHg in P (p=0.08). The surgical time for A was 26±0.8 minutes and 10±0.4 minutes for B (p<0.001). Following a low-pressure phase during the first week, A and P had an IOP value of 10.8±5.9 mmHg and 10.6±4.5 mmHg at 30 days, respectively (p=0.62). IOPs remained at this level throughout the study (all intra-group p> 0.08). There were no inter-group differences in IOP at any visit (all p-values > 0.3). Patients in A and P took 3.2 ± 1.3 and 3.3 ± 1.0 pressure-lowering medications at baseline, respectively (p=0.4). These values declined to 0.2 ± 0.6 in A and 0.3 ± 0.7 in P at 270 days. Both groups had a similar number of revisions (13 (10.3%) versus 10 (7.9%, p=0.14)) and complications (26 (20.8%) versus 31 (24.6%, all p>0.25). Conclusion: The posterior PRESERFLO insertion technique was 2.6 times faster than the standard anterior technique and yielded similar results with a large reduction in IOP and medications and a safety profile favorable over traditional filtering surgery.