Posterior Capsule Opacification, Nd:YAG Capsulotomy and IOL Dislocation
Last updated: November 2026
Months or years after a perfect cataract operation, patients return with blurred vision. The usual cause is posterior capsule opacification (PCO), a quick laser fix; less often, the lens itself has moved.
Posterior capsule opacification
- Lens epithelial cells grow onto the posterior capsule: Elschnig pearls (regenerative) or fibrosis.
- Risk is higher in children, uveitis, diabetes, and with round-edged or hydrophilic IOLs; a sharp-edged optic and good cortical clean-up reduce it.
- Symptoms: gradual blur, glare, loss of contrast, "my cataract has come back".
Nd:YAG capsulotomy
| Step | Practical points |
|---|---|
| Before | Confirm PCO explains the vision loss (check the macula, OCT if in doubt). Check IOP; brimonidine or apraclonidine before the laser reduces the IOP spike. |
| Settings | Start low (about 1–2 mJ per pulse) and increase only as needed; focus just behind the capsule to avoid pitting the IOL. |
| Pattern | Cruciate or circular opening about 3–4 mm, matched to the undilated pupil. |
| After | Check IOP at about 1 hour in glaucoma patients; short course of topical steroid if needed. |
Complications: IOP spike, IOL pitting, cystoid macular oedema, retinal detachment (higher in high myopes: warn about flashes and floaters), IOL dislocation through a large opening.
IOL dislocation
| Type | Cause | Management |
|---|---|---|
| Early (weeks) | IOL out of the bag or sulcus-placed lens after a capsule complication | Reposition, or exchange |
| Late in-the-bag (years) | Progressive zonular weakness: pseudoexfoliation, high myopia, uveitis, previous vitrectomy, retinitis pigmentosa | Reposition and scleral fixation of the bag-IOL complex, or exchange for an iris-fixated, scleral-fixated (for example Yamane technique) or anterior chamber IOL |
Symptoms include fluctuating vision, monocular diplopia, or an edge of the lens visible in the pupil. A lens dropped into the vitreous needs vitreoretinal surgery.
Where residents slip
- YAG for blurred vision that is actually macular oedema.
- Focusing on the IOL and pitting it.
- Not warning high myopes about retinal detachment symptoms after YAG.
Test yourself: flip cards
Related: IOL Lens Types Explained: Monofocal to Trifocal, Pseudoexfoliation Syndrome and Glaucoma, Lasers in Ophthalmology Made Easy: Time, Colour and Use.
Key sources
- Findl O, et al. Interventions for preventing posterior capsule opacification. Cochrane Database Syst Rev. 2010
- Yamane S, et al. Flanged intrascleral intraocular lens fixation with double-needle technique. Ophthalmology. 2017;124:1136-1142
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