The goal of this multicenter non-inferiority randomized controlled trial is to compare the efficacy of phacoemulsification with intraocular lens implantation (PEI) combined with goniotomy (GT) and PEI combined with medical therapy (MED) in the treatment of medically-controlled primary open-angle glaucoma (POAG) with cataract. The main questions it aims to answer are:

• Whether the PEI+GT was non-inferior to PEI+MED with regard to the intraocular pressure lowering effect in medically-controlled POAG.
• Whether the PEI+GT has value of health economics. Participants will be randomized to receive either PEI+GT or PEI+MED, and followed up with a 1-year period as a primary outcome.

Glaucoma is the leading cause of irreversible blindness worldwide, with primary open-angle glaucoma (POAG) remaining the most common subtype.

Although there are various methods to treat POAG, medication remains the first choice. However, medication therapy has several limitations, such as multiple adverse effects, poor compliance, and high costs. Therefore, it is imperative to explore treatment modalities that reduce medication burden and improve patients' quality of life.

Minimally invasive glaucoma surgery (MIGS) has been widely employed in clinical practice in recent years and become the mainstream surgical approach for POAG treatment. Among them, various forms of Schlemm's canal-based procedures, which were commonly known as ab interno trabeculotomy or goniotomy (GT) have garnered clinical significance due to their advantages of simplicity, minimal invasiveness, low complication rates, and rapid recovery. These procedures can also be combined with phacoemulsification with intraocular lens implantation (PEI). Currently, several GT techniques have been reported using different devices with different ranges of incision. The investigators have proved that a 120-degree GT with or with PEI were effective enough to treat patients with POAG with or without cataract, providing a comparable efficacy with 240 or 360 degree GT. The 120-degree is characterized by not only its efficacy, but also its fewer complications, faster procedure and quicker recovery. Although the techniques have been implemented clinically, further research is needed to evaluate their economics value in terms of reducing patient dependence on medication, relieving the economic burden of glaucoma medications, and improving the quality of life.

Therefore, a non-inferiority randomized controlled trial (RCT) will be conducted in medically controlled POAG patients with cataract, comparing PEI+GT to PEI combined with medication therapy (PEI+MED). The trial aims to validate the effectiveness of GT in reducing medication use, lightening the burden on patients, and providing a novel treatment approach.

Inclusion Criteria:

1. 40 ≤ Age ≤ 85 years, gender unrestricted.
2. Diagnosed with POAG.
3. Controlled IOP under 1 to 4 topical hypotensive medications, IOP ≤ 24 mmHg
4. Mean deviation (MD) for perimetry ≥ -16dB.
5. Presence of clinically significant cataract and best-corrected visual acuity measured using the ETDRS chart ≤ 0.63.
6. Voluntary participation of the patient in this study, signing an informed consent form, and agreeing to follow-up visits according to the study protocol.

Exclusion Criteria:

1. Any history of intraocular surgery or ocular trauma.

2. Presence of other types of glaucoma, including primary angle-closure glaucoma and various forms of secondary glaucoma (e.g. secondary angle-closure, pigmentary, steroid-induced, angle-recession, neovascular, inflammatory, and pseudoexfoliation syndrome).

3. Presence of severe ocular diseases of various types that affect the acquisition of ocular parameters or interfere with perimetry.

4. Axial length > 28 mm.

5. Monophthalmia (best-corrected visual acuity of the non-study eye < 0.01).

6. Coexistence of severe systemic diseases affecting the entire body.

7. Pregnant or lactating women.

   • If both eyes of a patient meet the criteria, the eye with worse visual acuity will be selected for inclusion.