- Medically Reviewed by: Mr Mfazo Hove, Consultant Ophthalmic Surgeon
- Author: Mr Mfazo Hove
- Published: December 12, 2024
- Last Updated: October 8, 2026
TL;DR: A temporary rise in eye pressure after ICL surgery can often be controlled with treatment, although some eyes need longer-term medication or further procedures.¹ Long-term glaucoma caused by an ICL is uncommon, particularly with modern central-port lenses, which have a small opening for fluid flow.² ³ The safeguards are careful lens sizing, checking the optic nerve, which carries visual information from the eye to the brain, before surgery, and measuring your eye pressure throughout the life of the implant.
An implantable collamer lens (ICL) is a lens placed inside the eye to correct your prescription.
Raised eye pressure is a risk factor for glaucoma, but it is not the same as glaucoma. Glaucoma involves damage to the optic nerve and can also occur when eye pressure is within the usual range.⁴
Pressure is measured, not assumed, at every visit, for the life of the implant.
Eye Pressure After ICL Surgery
The best study of this question followed 638 eyes after ICL surgery. Pressure rose to 22 mmHg or above in 33 eyes, about 5%, typically around 12 days after surgery. The abbreviation mmHg means millimetres of mercury, the unit used to measure eye pressure.¹
The causes were:
- A response to steroid eye drops in 64% of cases.
- Retained gel used during surgery in 15%.
- Pupillary block, where fluid flow behind the iris, the coloured part of the eye, is obstructed, in 12%.
- Two eyes with pre-existing glaucoma that had not been diagnosed before surgery.¹
In 31 of the 33 eyes, pressure returned to normal with medical treatment alone.¹
Two lessons follow:
- Pressure must be checked at the early reviews.
- The optic nerve must be examined properly before surgery, so that existing glaucoma is found rather than blamed on the ICL.
Why Modern ICLs Have Reduced the Risk
Older ICLs needed a small laser opening in the iris to prevent pupillary block. Central-port lenses for short-sight allow fluid to pass through the lens itself, removing the need for that opening and reducing the risk of pupillary block.² ³
This design does not prevent every cause of raised pressure. A response to steroid eye drops or retained surgical gel can still cause pressure problems.¹
Long-sighted lenses usually still need the opening. Blue Fin Vision® creates it with a YAG laser, a type of laser used to make a small opening in the iris, at Harley Street before surgery. This is included in the fee.
Long-Term Glaucoma Risks
The vault is the gap between the ICL and your natural lens. If this gap is too large, the lens can narrow the drainage angle, the area between the iris and cornea where fluid drains from the eye. The cornea is the clear front surface of the eye.
Over the years, pressure problems can arise from this narrowing or from pigment rubbed from the iris clogging the drainage system.⁵
The vault is not fixed. It changes gradually over time, which is why it is measured throughout the life of the implant rather than once.⁶
How Blue Fin Vision® Monitors Pressure
At Blue Fin Vision®, our eye clinic assesses your eyes before surgery and monitors pressure throughout your follow-up care.
- Before surgery. Your drainage angle, optic nerve and anterior chamber, the fluid-filled space between the cornea and iris, are assessed. The lens is sized to a safe vault.
- Follow-up protocol. Following a three-year audit in which routine same-day pressure checks and day-one reviews did not change management, Blue Fin Vision® revised its follow-up protocol.
- Early reviews. Your consultant contacts you the day after surgery, with an examination arranged whenever clinically indicated. Pressure is measured at one week, one month, three months and twelve months.
- Urgent symptoms. Pain, headache, nausea or blurred vision after surgery require urgent assessment. Sudden severe eye pain, particularly with blurred vision, headache or nausea, can be a medical emergency. Do not drive yourself or wait for your next scheduled appointment.⁴
- For life. Under the ICL Lifetime Monitoring Protocol™, pressure is checked at every monitoring visit. A vault outside our 250 to 750 micrometre target range triggers a consultant review at no additional cost. A micrometre is one-thousandth of a millimetre.
- If glaucoma is found. Glaucoma unrelated to the ICL falls outside the Protocol and is managed through our glaucoma care service. The Protocol states that boundary plainly, because a promise that covers everything usually means nothing.
Glaucoma often develops without noticeable symptoms, so regular checks remain important even when your eyes feel comfortable.⁴
Further Reading
Read these supporting resources before your consultation:
- Our ICL risks page.
- Our phakic intraocular lens information, covering lenses implanted while your natural lens remains in place.
- Our ICL surgery checklist.
References
- Senthil S, Choudhari NS, Vaddavalli PK, Murthy S, Reddy JC, Garudadri CS. Etiology and management of raised intraocular pressure following posterior chamber phakic intraocular lens implantation in myopic eyes. PLoS One. 2016;11(11):e0165469. doi:10.1371/journal.pone.0165469. PMID:27855172.
- Packer M. The Implantable Collamer Lens with a central port: review of the literature. Clin Ophthalmol. 2018;12:2427-38. doi:10.2147/OPTH.S188785.
- Montés-Micó R, Ruiz-Mesa R, Rodríguez-Prats JL, Tañá-Rivero P. Posterior-chamber phakic implantable collamer lenses with a central port: a review. Acta Ophthalmol. 2021;99(3):e288-e301. doi:10.1111/aos.14599.
- NHS. Glaucoma [Internet]. NHS; 2025 Jun 13 [cited 2026 Oct 6].
- Fernandes P, González-Méijome JM, Madrid-Costa D, Ferrer-Blasco T, Jorge J, Montés-Micó R. Implantable collamer posterior chamber intraocular lenses: a review of potential complications. J Refract Surg. 2011;27(10):765-76. doi:10.3928/1081597X-20110617-01.
- Schmidinger G, Lackner B, Pieh S, Skorpik C. Long-term changes in posterior chamber phakic intraocular collamer lens vaulting in myopic patients. Ophthalmology. 2010;117(8):1506-11. doi:10.1016/j.ophtha.2009.12.013.
ABOUT THE AUTHOR
Mr Mfazo Hove
Consultant Ophthalmic Surgeon
MBChB MD FRCOphth CertLRS
Mr Mfazo Hove is a Consultant Ophthalmic Surgeon with experience spanning more than 57,000 procedures. He completed 6.5 years of specialist training at Moorfields Eye Hospital and served for five years as a consultant at the Western Eye Hospital, Imperial College Healthcare NHS Trust. He is the founder of Blue Fin Vision®, a consultant-led private ophthalmology practice operating across London, Essex, and Hertfordshire. His clinical expertise encompasses advanced cataract surgery, refractive lens replacement, laser vision correction, and implantable Collamer lenses (ICL).
A ZEISS Key Opinion Leader, Mr Hove is a respected international speaker with five invited engagements across seven cities in 2026:
- ZEISS China tour (Changsha, Shanghai, and Hangzhou, April – ZEISS APAC User Meeting)
- RCOphth Annual Congress – May – Manchester
- ZEISS EMEA User Meeting (Istanbul)
- ZEISS Lausanne User Meeting (Lausanne)
- European Society of Cataract and Refractive Surgeons Annual Congress (ESCRS, London)
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