Xen 45: Comparison Of Efficacy And Safety Between Ab Externo And Ab Interno Approaches

To compare the safety and efficacy of two different techniques (ab externo and ab interno) for implantation of the XEN®45 Gel Stent (Allergan Inc., CA, USA), a minimally invasive surgical device for the treatment of glaucoma. Previous studies are scarce and showed no differences in efficacy and safety between both approaches.

The diagnosis, surgical indication, surgical procedure and postoperative follow-up were carried out by glaucoma specialist at the Vall d'Hebron University Hospital, Barcelona, Spain.

A retrospective analysis of XEN®45 implants performed at Vall d'Hebron Hospital (both ab interno and ab externo) from March 2017 to March 2023 was conducted.

Primary outcomes included mean intraocular pressure (IOP) reduction at 6 months and 12 months and postoperative complications.

The secondary objectives of the study included the mean reduction of hypotensive drugs employed one year after the surgery for IOP control, the need for secondary needling and the progression of glaucoma 1 year after the surgery.

Statistical results were obtained using the SPSS® program.

41 ab interno and 40 ab externo were included. Both groups had similar baseline characteristics.The ab interno group showed a mean IOP reduction of 2.2±5.4 mmHg and 2.6±5.6 mmHg at 6 and 12 months, respectively, compared to a mean reduction of 11.1±8.5 mmHg and 10.3±8.6 mmHg in the ab externo group, with statistical significancy. There were no cases of hypotonic maculopathy nor choroidal detachment in both groups. Secondary needling was required in 11 and 7 cases in ab interno and ab externo groups, with no statistical significancy. Glaucoma progression was significantly higher in the ab interno group. Mean reduction in treatment use was 2.2±1.4 and 0.9±0.9 in ab externo and ab interno groups, with no statistical differences.

Both approaches for XEN implant were safe without vision-threatening complications. Moreover, mean IOP reduction was significantly higher at 6 and 12 months in the XEN ab externo compared to the XEN ab interno group. Progression of glaucomatous neuropathy was higher one year after in the Lower need of secondary needling and of glaucomatous medication were observed in the ab externo group, although not being significative.