Managing IOP Spikes After Cataract Surgery: A Shared-Care Guide

Managing patients through the weeks after cataract surgery is one of the most valuable things we do together in shared care. Most intraocular pressure (IOP) rises in this window are transient, but knowing the mechanisms behind them, and recognising when a spike needs escalation, is what protects the patient's vision. This is a short, practical guide to the post-cataract pressure spike: how to think about it, what to check, and when to pick up the phone.

Case study: raised IOP two weeks after cataract surgery

Consider a 64-year-old woman two weeks after uncomplicated cataract surgery in the right eye. Her day-one check was normal, with an IOP of 17 mmHg against a pre-operative baseline of 15. Now she reports mild, painless blurring. Acuity is 6/9, pinholing to 6/6, but her IOP has climbed to 32 mmHg.

The anterior chamber is deep and quiet, with no cells or flare. The cornea shows mild microcystic oedema and the IOL sits perfectly centred in the bag. Gonioscopy shows a wide-open angle through 360 degrees, with no retained lens material, pigment band or peripheral anterior synechiae (PAS).

Given the timeline, the quiet eye, and her use of prednisolone acetate 1% four times daily, this is highly characteristic of a steroid response. Management is to start a topical aqueous suppressant, such as timolol 0.25% twice daily, to bring the pressure down safely, while tapering the steroid or switching to a lower-potency agent such as FML three times daily under close review. A recheck within three days confirms the pressure has normalised.

Causes of post-cataract IOP elevation, by timeline

When you meet a raised post-op pressure, the timeline and the structural picture point you to the cause. A useful definition of a significant spike is an IOP above 30 mmHg that also exceeds baseline by more than 10 mmHg. These occur in roughly 3.7% of eyes in the first week after phacoemulsification, rising to about 5.2% in patients with pre-existing glaucoma and 4.6% in glaucoma suspects.

Open-angle mechanisms. Retained viscoelastic (OVD) typically presents acutely on day one, obstructing the trabecular meshwork. A steroid response tends to appear at two to three weeks. Lens-particle glaucoma can occur days to weeks later from retained fragments, while pigment dispersion or UGH (uveitis–glaucoma–hyphaema) syndrome may appear weeks, months or even years on.

Closed-angle mechanisms. Pupillary block is rare in pseudophakia (around 7 in 10,000) and is driven by severe inflammation and 360-degree posterior synechiae. Malignant glaucoma presents with a uniformly shallow or flat anterior chamber, driven by choroidal expansion and an abnormal transvitreal pressure gradient. Focal PAS and, rarely, suprachoroidal haemorrhage also sit in this group.

Toxic mechanisms. Toxic anterior segment syndrome (TASS) is an acute, sterile inflammatory reaction to an intraoperative toxin. It develops fast, within 12 to 48 hours, with diffuse corneal oedema, high IOP and fibrinous exudate, and must be distinguished immediately from infectious endophthalmitis.

Figures above are drawn from the American Academy of Ophthalmology's guidance on managing IOP spikes after cataract surgery (aao.org).

How to assess a post-op IOP spike: three checks

• Perform early gonioscopy. If pressure is unexpectedly raised weeks after surgery, look at the angle for hidden lens fragments, subtle PAS or pigment dispersion.
• Check for transillumination defects. Retroillumination of the iris can reveal defects pointing to IOL haptic chafing, especially where you see trace cells or micro-hyphaema.
• Differentiate the shallow chamber. If the anterior chamber is flat or uniformly shallow, separate pupillary block from malignant glaucoma by checking for a patent iridotomy and looking for choroidal effusions.

Two things optometrists commonly miss

• When you assess the anterior chamber, look specifically for retained viscoelastic. A tell-tale sign is cells that move less freely in the AC than you'd expect.
• If you regularly co-manage these patients, consider becoming a glaucoma-endorsed prescriber. It makes starting and adjusting treatment far more straightforward for you, and quicker for the patient.

When and how to refer to Re:Vision

If you see a post-op pressure spike, please get in touch — early contact is always better than waiting. You can reach me directly by phone or email, or refer through the Academy referral form on our website.

• An independent glaucoma prescriber can start drops and co-manage the patient with me.
• A therapeutic-endorsed optometrist is welcome to discuss the case, and we'll agree the right treatment together, case by case.

Thank you for the care you take with these patients through the post-operative period. If you ever encounter a refractory or suspicious pressure spike, don't hesitate to reach out for guidance or a prompt referral.

— Dr Divya Perumal