Piggyback lens implants: correcting vision after cataract surgery

Where does the extra lens sit?

During cataract surgery, the cloudy natural lens is removed and an artificial lens is usually placed inside its thin supporting capsule, called the capsular bag. A supplementary IOL sits in a different space: the ciliary sulcus, just behind the iris and in front of the existing implant.

The two implants have separate supports. The supplementary lens changes the eye's combined focusing power without requiring the original lens to be freed from its capsule. It is different from placing two ordinary cataract lenses together inside the bag, an older approach associated with clouding between the lenses.

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Why does the lens design matter?

If a lens made only for the capsular bag is placed in the sulcus, its edges or supporting arms may rub the iris, releasing pigment and causing inflammation, bleeding or raised eye pressure. This is a recognised source of complications.

Purpose-designed supplementary lenses have a shape and supports intended for that position, including clearance from the original implant and the iris. Some are single-piece lenses themselves, so “single-piece” alone does not tell you whether a lens is suitable. Its intended use, design, sizing and position are what matter.

Rayner Sulcoflex and 1stQ AddOn use different support designs. They are examples of this specialist category, not interchangeable implants chosen simply by brand preference.

What can Sulcoflex and AddOn correct?

Depending on the model, these lenses can correct remaining short-sightedness or long-sightedness. Toric versions also correct astigmatism: an uneven focusing power in different directions. A toric implant must remain aligned correctly to work well. The guide to toric lens implants explains that principle.

A supplementary lens is most useful when an accurate glasses prescription substantially improves the vision and the remaining prescription is the problem you want to address. It does not repair a damaged retina, treat dry eye or remove clouding of the capsule behind the original implant. Nor does it reliably solve every unwanted visual effect from a multifocal implant.

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Some supplementary models aim to extend the range of focus or reduce reading-glasses dependence. That is a different goal from correcting an unexpected distance prescription. Multifocal or extended-depth-of-focus options need their own discussion of contrast, glare and halos, especially if the original implant already splits light between several distances.

Who might be suitable?

A supplementary lens may be considered when the original implant is stable, the eye has suitable space and support, and the likely benefit is worth another intraocular operation. It can be useful when corneal laser treatment is unsuitable or when removing a well-fixed original implant would add difficulty.

Assessment normally includes the glasses prescription, corneal measurements, eye pressure, the position of the first implant and examination of the retina. Dry eye or other treatable causes of poor vision should be addressed before the final measurements. Previous cataract records and the original implant details are useful.

A shallow front chamber, narrow drainage angle, unstable capsule or weak supporting fibres, iris adhesions, inflammation or pressure problems may make the approach unsuitable. Previous retinal or corneal surgery can change the balance. Tell your surgeon about any likely future operation involving air or gas inside the eye, because this can matter for some hydrophilic lens materials.

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How long should I wait after cataract surgery?

There is no single waiting period that suits everyone. For a refractive correction, the eye should have healed sufficiently and repeated measurements should show a stable prescription. Decisions are usually made over weeks or months, rather than from the first postoperative glasses check alone.

A supplementary implant can sometimes be placed years later. The number of years since cataract surgery is less important than the current anatomy and reason for treatment. If a major implant problem is identified early, discuss it promptly: delaying every decision until an arbitrary date can make some alternatives harder.

If lens exchange remains a possibility, discuss it before having YAG laser to open a cloudy posterior capsule. An open capsule changes the risks and options for later surgery; it does not automatically rule out a supplementary lens.

How does it compare with glasses, laser or lens exchange?

Glasses or contact lenses may provide the correction without another operation. If they give comfortable vision and fit your needs, further surgery may offer little extra benefit. The article on glasses after cataract surgery explains why needing a prescription does not necessarily mean the operation went wrong.

Corneal laser correction, such as LASIK or PRK, changes the shape of the front of the eye. It may suit some stable prescriptions, provided the cornea and tear film are suitable. It has its own risks and healing requirements.

Repositioning the original toric lens may address astigmatism caused by rotation. Adding another lens is not automatically the first answer to a rotated implant.

Lens exchange removes and replaces the original implant. It may be more appropriate when the first lens itself is damaged, poorly positioned or has an optical design you cannot tolerate. Removing a lens that has become attached to its capsule can be more involved. See whether a lens implant can be replaced.

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What happens during the operation?

Your surgeon confirms the supplementary lens power from the current refraction and measurements, using a calculation appropriate to that lens and its position. Its power is not simply copied from your glasses prescription.

The folded lens is inserted through a small incision and its supports positioned in the sulcus. A toric model is aligned to the planned axis. The surgeon checks the relationship between the iris, supplementary lens and original implant. The anaesthetic and sedation plan is discussed beforehand.

Dr Chen's video below shows a 1stQ AddOn lens being implanted for an unexpected refractive result after cataract surgery. It contains close-up surgical footage.

Play operation · 4:08 →

What does treatment and recovery involve?

The operation is usually planned as day surgery. The original implant stays in its capsule; the extra lens is inserted through a small incision and positioned in front of it. The following is a planning guide, with your own instructions taking priority.

What is normal in the first few days?

Some grittiness, watering, mild discomfort and temporarily unsettled vision can occur. These should generally improve. Use your drops exactly as directed; do not stop them just because the eye feels comfortable. Reading and screens can be resumed as comfort allows, but driving requires both suitable vision and your surgeon's advice.

Increasing pain, increasing redness or worsening vision needs prompt assessment. Do not assume it is simply the lens “settling”. The warning signs are listed near the end of this article.

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What benefits and risks should I weigh up?

The main potential benefit is better vision without distance glasses while retaining a stable original implant. Published studies report improved prescriptions and unaided vision in selected patients. Much of the evidence comes from relatively small observational studies, which cannot guarantee your result or reliably quantify uncommon complications.

Risks include an inaccurate remaining prescription, lens movement or rotation, iris rubbing, inflammation, bleeding, raised pressure and swelling at the central retina. Infection, retinal detachment and lasting loss of vision are also possible after intraocular surgery. Further treatment may involve drops, repositioning, removing the supplementary lens or another operation.

Toric rotation deserves particular attention. An older Sulcoflex toric study reported frequent repositioning, whereas a small selected AddOn toric study found good alignment. These studies involved different lenses and patients and are not a head-to-head comparison of current products. Ask about the proposed model and how a rotation would be managed.

An additional implant can sometimes be removed without removing the first one, but “removable” does not mean risk-free or guaranteed to restore the previous situation. You may still need glasses afterwards, particularly for reading.

What should I ask at my consultation?

• What is causing my current difficulty, and how much does a glasses correction improve it?
• Why do you recommend an extra lens rather than glasses, laser, repositioning or exchange?
• Which exact model would you use, and what result is realistic for each eye?
• Are my capsule, iris, cornea, pressure and retina suitable?
• What is the plan if the lens rotates, the prescription remains off target or I dislike the result?
• What follow-up and total costs should I expect?

Bring your current glasses, medication list and any available cataract-surgery records. The aim is a useful improvement in your everyday vision with a balance of benefit and risk you understand.

When should I seek urgent help?

Contact your surgeon urgently for increasing or severe eye pain, increasing redness, a sudden drop in vision, marked light sensitivity, new flashes or a sudden shower of floaters, or a shadow or curtain across the vision. Eye pain with headache, nausea or vomiting also needs prompt assessment.

Do not wait for a scheduled review. If your surgeon cannot be reached, seek urgent ophthalmic care or attend the nearest emergency department. Do not drive yourself if your vision is affected.