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Comparison of 1-year surgical outcomes of combined cataract surgery and gonioscopy-assisted transluminal trabeculotomy (GATT) versus cataract surgery and iStent Inject

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Evaluate the efficacy, safety, and complication rates of phacoemulsification cataract surgery when combined with either gonioscopy-assisted transluminal trabeculotomy (GATT) or iStent Inject.


This is a retrospective case-control study to compare the surgical outcomes of combined phacoemulsification cataract surgery with either GATT (phaco-GATT) or iStent Inject (phaco-iStent). Both groups had at least 1-year follow-up. The primary outcome measures were IOP and number of glaucoma medications (NGMs) at 1 year. Secondary outcomes measures were best corrected visual acuity (BCVA) and intra- or postoperative complications within the first year of follow-up. Success was defined as intraocular pressure (IOP) < 21 mmHg and ≥ 20% reduction in IOP at 1 year regardless of the NGM.


Each group included 37 patients. The median baseline IOP (24 vs 17) and NGM (3 vs 2) were higher in the phaco-GATT group (p < 0.001). Phaco-GATT achieved a 38% (p < 0.0001) reduction in IOP compared to 13.2% (p < 0.001) in the phaco-iStent group at 1-year follow-up. The reduction in IOP and NGM was significantly higher in the phaco-GATT group (p < 0.01). After adjusting for baseline IOP, the reduction in IOP at 12 months was still significantly higher in the phaco-GATT group (p = 0.042). At 1 year, 86.4% of patients in the phaco-GATT group met the success criteria compared to 35.1% in the phaco-iStent group. Safety outcomes were slightly favourable in the phaco-iStent group.


Phaco-GATT and phaco-iStent showed a significant reduction in IOP and NGM, with phaco-GATT having a significantly higher reduction. Phaco-iStent appears to have a higher safety profile and is probably preferable in monocular patients and those with a high risk of bleeding.

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Correspondence to Imran Masood.

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All procedures performed in studies involving human participants were in accordance with the ethical standards of the Sandwell and West Birmingham NHS Trust and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

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Imran Masood is consultant to Glaukos. Glaukos had no knowledge, awareness, influence or involvement in our study. Specifically, there was no funding received from Glaukos for this study. Velota Sung, Pravin Pandey, Abhijit Mohite and Hisham Hamze have nothing to disclose.

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Hamze, H., Mohite, A.A., Pandey, P. et al. Comparison of 1-year surgical outcomes of combined cataract surgery and gonioscopy-assisted transluminal trabeculotomy (GATT) versus cataract surgery and iStent Inject. Graefes Arch Clin Exp Ophthalmol 259, 3035–3044 (2021).

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