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To manage the increasing prevalence of glaucoma, we need access to effective and safe medical and surgical treatments that can lower the intraocular pressure (IOP) – so far the only proven strategy to slow disease progression. Treatment typically starts with eye drops or a laser procedure, but many patients will eventually require surgery. Traditional surgery is time-consuming and carries significant risks, whereas microinvasive glaucoma surgery (MIGS) has emerged as a safer, earlier option that could potentially prevent or delay more invasive procedures such as a trabeculectomy. Additionally, many patients with glaucoma develop cataract, and MIGS procedures can be conveniently performed together with the cataract operation. Although MIGS is now widely adopted, concerns about bias remain as many studies are industry-funded. The benefit of combining MIGS with cataract surgery is also debated, especially in advanced glaucoma. Moreover, research is scarce for pseudoexfoliation glaucoma (PEXG), common in the Nordic countries and harder to treat, with a poorer prognosis than other open-angle glaucoma types.

In this thesis, we evaluate the efficacy and safety of the trabecular MIGS procedures iStent inject® (iStent) and Kahook Dual Blade® (KDB) across various stages and subtypes of glaucoma. We show that KDB is effective and safe when combined with cataract surgery, whereas its efficacy as a stand-alone procedure is lower. Therefore, we do not recommend the stand-alone approach in patients with advanced or uncontrolled glaucoma.

Furthermore, iStent and KDB demonstrate comparable outcomes, showing effectiveness not only in mild to moderate disease but also in advanced stages and in PEXG. Our results show that trabecular MIGS combined with cataract surgery is effective even in patients with markedly elevated IOP and/or on maximum tolerated therapy. These patients, previously considered candidates for bleb-forming surgery, may instead begin with trabecular MIGS combined with cataract surgery. Many patients undergoing trabecular surgery have previously received laser trabeculoplasty (LTP), and we show that LTP does not seem to negatively affect the surgical outcomes of cataract surgery combined with KDB.

Finally, surgical success can be enhanced if iStent or KDB is added to the cataract operation, and in stable glaucoma patients this will mainly be due to greater medication reductions. Postoperative IOP spikes can also be reduced by more than half by adding iStent or KDB.

In summary, this thesis demonstrates that trabecular MIGS as a stand-alone procedure offered only moderate success and often required further interventions. Therefore, we do not recommend the stand-alone approach in patients with advanced or uncontrolled glaucoma. When performed together with cataract surgery, our data show that trabecular MIGS is both effective and safe – even in patients with markedly elevated IOP and/or on maximum tolerated therapy. In more stable glaucoma patients with lower preoperative IOP levels and a low rate of progression, combining trabecular MIGS with cataract surgery can be considered when medication reduction is a clinical goal. This approach also lowers the risk of early IOP spikes, and both iStent and KDB perform equally well, with comparable outcomes in PEX and non-PEX eyes.