Multifocal IOL: Patient Selection and Photic Phenomena

Multifocal IOL designs split light between distance and near foci to reduce the need for glasses after cataract surgery.

The trade-off is lower contrast and more halos and glare, especially at night.

Therefore, patient selection decides satisfaction more than the lens itself.

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How a Multifocal IOL Works

Diffractive designs divide light between foci with concentric steps.

Refractive designs use zones of different power.

Bifocal lenses give distance and near, and trifocal lenses add an intermediate focus.

Also, the brain must learn to ignore the out-of-focus image, which takes time.

Benefits of a Multifocal IOL

Systematic reviews found that patients with multifocal lenses need glasses less often than those with monofocal lenses.

Also, near vision is better without correction.

Therefore, motivated patients who want freedom from glasses may be well served.

Photic Phenomena With a Multifocal IOL

Halos and glare around lights are common, and they are most bothersome at night.

Contrast sensitivity falls slightly, even when acuity is good.

Also, most patients adapt with time through neuroadaptation, but a minority stay bothered.

Because the effect is part of the design, explain it before surgery.

Choosing the Right Multifocal IOL Candidate

Good candidates have healthy eyes, realistic expectations and a wish for spectacle independence.

Check the ocular surface, the macula, the optic nerve and the cornea carefully (see dry eye disease).

Patients with macular disease, glaucoma or irregular corneas are poor candidates.

Also, think twice for night drivers and for patients with demanding visual tasks.

Counselling Before Surgery

Describe the halos in clear terms and show a simulation if you can.

Explain that a small residual error may need glasses or laser enhancement.

Also, discuss the chance of a lens exchange if the patient cannot adapt.

Because surprise causes dissatisfaction, give the same message in writing.

Causes of Dissatisfaction With a Multifocal IOL

Residual refractive error is the most common cause and the easiest to fix.

Dry eye, posterior capsule opacification and decentration also reduce quality (see YAG laser capsulotomy).

Negative dysphotopsia and other lens-related effects may add (see negative dysphotopsia).

Therefore, look for the cause before you blame the lens.

Managing the Unhappy Patient

Treat the surface and refine the refraction first.

Wait for neuroadaptation over several months.

If symptoms persist, an IOL exchange is possible but carries risk (lens exchange is possible but carries risk).

Alternatives

Monovision, extended depth of focus and enhanced monofocal lenses suit some patients.

Each has its own trade-offs.

Also, a monofocal lens with spectacles remains a safe option.

Types of Multifocal IOL

Diffractive lenses split light by steps on the optic.

Refractive lenses use annular zones with different powers.

Also, hybrid designs combine the two approaches.

Because designs differ in distance and near performance, pick one that fits the patient’s needs.

Neuroadaptation

The brain learns to suppress unwanted images over weeks to months.

Most patients notice fewer halos with time.

Also, a stable ocular surface and a clear capsule speed the process.

Therefore, advise patience and avoid early lens exchange.

Ocular Surface and Multifocal IOL Outcomes

Dry eye reduces the quality of the image, and multifocal optics make this more obvious.

Treat blepharitis and meibomian gland disease before surgery.

Also, check the tear film with staining and tear breakup time.

Because the surface limits quality, optimize it first.

Biometry and Astigmatism

Accurate biometry is essential, since multifocal lenses tolerate little residual error.

Correct corneal astigmatism above half a diopter with a toric design or a relaxing incision.

Also, plan laser enhancement if a small error remains.

Therefore, expect a more careful workflow than for a monofocal lens.

Posterior Capsule Opacification

Even mild opacity reduces contrast and increases halos.

A laser capsulotomy often restores quality.

Also, schedule the laser early in patients who complain of blur.

Because opacity is common, include it in counseling.

Alternatives for Spectacle Independence

Extended depth of focus lenses give less near vision but fewer halos.

Monovision uses one eye for distance and one for near.

Also, enhanced monofocal lenses offer a modest range without added halos.

Therefore, match the option to the patient’s priorities.

Practical Screening Questions

Ask what the patient does all day, and how much they dislike glasses.

Ask about night driving, reading in dim light and fine work.

Also, ask how they feel about halos around lights.

Because the answers show priorities, they help you decide between lens types.

Then record the discussion in the chart.

For the latest studies, see the PubMed results for multifocal IOL.

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References

1. de Vries NE, Nuijts RMMA. Multifocal intraocular lenses in cataract surgery: literature review of benefits and side effects. J Cataract Refract Surg. 2013;39:268-278.
2. Calladine D, Evans JR, Shah S, Leyland M. Multifocal versus monofocal intraocular lenses after cataract extraction. Cochrane Database Syst Rev. 2012;(9):CD003169.
3. Woodward MA, Randleman JB, Stulting RD. Dissatisfaction after multifocal intraocular lens implantation. J Cataract Refract Surg. 2009;35:992-997.
4. Alio JL, Plaza-Puche AB, Fernandez-Buenaga R, Pikkel J, Maldonado M. Multifocal intraocular lenses: an overview. Surv Ophthalmol. 2017;62:611-634.