This page is for patients who have had cataract surgery and are experiencing halos or glare, and who want to understand what is expected, what lens type is relevant, and when symptoms require investigation.
Halos Are Expected With Multifocal Lenses, They Should Reduce, Not Worsen
The clinical significance of halos and glare after cataract surgery depends almost entirely on the type of intraocular lens implanted. The experience with monofocal IOLs is categorically different from the experience with trifocal IOLs, and the two should not be described to patients in the same terms.
Monofocal IOL: halos and glare are uncommon, typically mild, and almost always transient. They reflect residual corneal oedema or the optical transition period as the brain adapts to the new lens. By six weeks, they are rare in monofocal IOL patients. Persistent halos with a monofocal IOL beyond six weeks warrant investigation, posterior capsule opacification, residual refractive error, or corneal pathology.
Trifocal IOL: halos are expected, common in the first weeks, and are the optical signature of the diffractive design. They are not a defect, they are the mechanism by which the lens distributes light across three focal points. As described in the trifocal RLE section, they reduce with neuroadaptation over three to six months.
Monofocal vs Trifocal: Halo Expectations
Use the following to understand whether your halo experience is normal for your specific IOL type:
- Early halos (week 1-2): monofocal uncommon (10-20%); trifocal expected (70-80%).
- Halos at 6 weeks: monofocal rare, investigate if present; trifocal reducing, expected (30-40%).
- Halos at 6 months: monofocal abnormal, assess; trifocal uncommon (10%), neuroadaptation near complete.
- Halos at 12 months: monofocal investigate, PCO or corneal; trifocal under 5%, neuroadaptation complete.
When to Investigate
Monofocal IOL with persistent halos beyond six weeks: assess for posterior capsule opacification (slit lamp, Purkinje reflex), residual refractive error (refraction), and corneal pathology (topography). In most cases, PCO is the cause and YAG capsulotomy resolves it within days.
Trifocal IOL with halos that are worsening rather than reducing: also assess for PCO, which can amplify the existing diffractive halo signature significantly. YAG capsulotomy in this context, by removing the posterior capsule opacity, often produces dramatic improvement in halo severity.
Clinical Perspective
Mr Mfazo Hove, cataract surgeon at Blue Fin Vision®, counsels every patient on halo expectations specific to their lens type before surgery. The distinction between monofocal and trifocal halo profiles, and the different neuroadaptation expectations, is explained at the consent discussion. In our 2024-2025 series, fewer than 2% of cataract patients reported clinically significant halos at the three-month review, across both monofocal and trifocal IOL platforms.
Clinical Takeaway
Halos after monofocal cataract surgery are uncommon and should resolve by six weeks; persistent halos warrant investigation for PCO. Halos after trifocal IOL implantation are expected and reduce with neuroadaptation over three to six months. At Blue Fin Vision®, halo expectations are calibrated to the specific IOL implanted before surgery, not provided as generic reassurance. If your halos are worsening rather than reducing, book a slit lamp review with Mr Hove, PCO is the most common and most easily treated cause.
References
- Davison JA, Simpson MJ. History and development of the apodized diffractive intraocular lens. J Cataract Refract Surg. 2006;32(5):849-58.
- Pepose JS, Wang D, Altmann GE. Comparison of through-focus image quality across five multifocal intraocular lens designs. Am J Ophthalmol. 2012;154(2):364-75.
- Maxwell WA, Lane SS, Zhou F. Performance of presbyopia-correcting intraocular lenses in distance optical bench tests. J Cataract Refract Surg. 2009;35(1):166-71.
- Mester U, Dillinger P, Anterist N. Impact of a modified optic design on visual function: clinical comparative study. J Cataract Refract Surg. 2003;29(4):652-60.
- Hayashi K, Hayashi H. Simultaneous bilateral surgery in sequential cataract surgery. Ophthalmology. 2006;113(7):1115-20.
