iStent inject and Kahook goniotomy come out level, on a small trial

Design

prospective single-surgeon randomised controlled trial

Population

68 eyes (35 phaco-iStent inject, 33 phaco-Kahook Dual Blade) with open-angle glaucoma or ocular hypertension

Primary outcome

intraocular pressure reduction and surgical success at up to 12 months, mean follow-up 8 ± 2.4 months

Effect

IOP 19.37 to 16.58 mmHg vs 18.15 to 15.46 mmHg, about 14% in each (P = .355 at 6 months); complete success 68.8% vs 62.5%

Sixty-eight eyes with open-angle glaucoma or ocular hypertension were randomised by a single surgeon between 2024 and 2025 to phacoemulsification with iStent inject implantation (35 eyes) or with Kahook Dual Blade goniotomy (33 eyes). Mean follow-up was 8 ± 2.4 months.

Intraocular pressure fell by about 14 per cent in both arms with no difference between them (P = .355 at six months): from 19.37 ± 4.03 to 16.58 ± 3.64 mmHg with iStent and 18.15 ± 3.76 to 15.46 ± 3.15 mmHg with the Dual Blade. Mean medication burden fell to zero in both groups. Complete surgical success at six months was 68.8 per cent and 62.5 per cent. Corneal oedema and hyphaema were the commonest adverse events and were more frequent after goniotomy, though all resolved without further surgery.

With 68 eyes, one surgeon and eight months of follow-up, this cannot establish equivalence — it can only say that no difference was visible at this size. What it does support, and what matters more in practice, is that both procedures eliminated topical medication in most eyes. Where that holds, the choice between them turns on cost and on the hyphaema and corneal oedema profile, and the Kahook Dual Blade is substantially cheaper, which is the deciding consideration in most Indian units.

• Do not read this as equivalence — 68 eyes cannot establish it
• Note the medication burden went to zero in both arms; that is the outcome patients feel
• Expect more hyphaema and corneal oedema after Dual Blade goniotomy, self-limiting in this series
• Where both are available, let cost and the adverse event profile decide
• Treat the follow-up as short; both procedures need durability data beyond a year

Why it matters

Both canal-based procedures are being sold on comparative superiority claims that a trial this size cannot support either way.

Don't overread it

A single-surgeon randomised trial of 68 eyes with a mean of eight months' follow-up — underpowered for any between-group comparison.

The statistics, in plain English

P = .355 in a trial of 68 eyes means no difference was detected, not that none exists — a trial this size would miss anything short of a large effect. The authors also note follow-up thinned over time, which makes the twelve-month figures less reliable than the six-month ones.

Read the rest in the app

You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.

Get Daily Doctor — free

Scan to keep reading on your phone. No account needed to start.