Management practices and surgical techniques for ab externo less invasive glaucoma surgery: a literature review and expert recommendations.

Purpose: Subconjunctival bleb-forming devices (SBD) can provide greater intraocular pressure reductions than minimally invasive glaucoma surgery (MIGS) whilst remaining less invasive than traditional surgical techniques. However, variations in management practices and surgical techniques indicate the need for concise and clear guidance on these procedures in diverse patient populations. Here we describe current recommendations on the use of PRESERFLO MicroShunt, an ab externo SBD, according to a review of current literature and the opinions of 20 international glaucoma experts.

Methods: A literature search was performed to return all publications relating to the PRESERFLO MicroShunt, which were then reviewed to extract information or guidance on patient selection, pre-operative patient preparation, peri-operative practices and techniques, and post-operative management. Alongside the literature search findings, participants in an expert panel meeting discussed their current practices relating to these same four aspects of PRESERFLO MicroShunt use.

Results: PRESERFLO MicroShunt can be considered for the majority of patients with medically uncontrolled open-angle glaucoma, as well as in patients with uveitic glaucoma, advanced glaucoma and high myopia, adults with congenital glaucoma, and in some cases normal tension glaucoma patients. Prior to surgery, steroid drops may be given for 2-4 weeks if feasible, and acetazolamide may also be useful in patients with advanced glaucoma and high IOP. During surgery, a deep (8 mm) and wide sub-Tenon pocket is essential to surgical success. Mitomycin C is generally used at a concentration of 0.4 mg/mL for a minimum of 2-3 min. Intracameral bevacizumab and/or dexamethasone may be considered to increase the chance of surgical success. Post-operatively, antibiotics should be given for 7 days and steroid drops for 3-6 months. Monitoring visits may be less frequent than in patients undergoing trabeculectomy.

Conclusion: Management practices and surgical techniques for ab externo SBD vary, and surgeons must use their best clinical judgement based on the requirements of the individual patient. However, here we provide some recommendations for patient selection and pre-, peri- and post-surgical management based on the opinions of experts in the use of PRESERFLO MicroShunt, which we hope will prove useful in optimizing surgical outcomes.