Hydrophobic vs hydrophilic acrylic lens implants: pros and cons

What do hydrophobic and hydrophilic mean?

Both are foldable plastics used for an intraocular lens (IOL), the implant that replaces the natural lens during cataract surgery or refractive lens exchange. Hydrophilic means water-attracting: the polymer contains a substantial amount of water. Hydrophobic acrylic has a much lower water content, although it is not completely water-free.

A hydrophobic surface treatment changes the outside of a hydrophilic implant. It does not change the underlying water-rich material into bulk hydrophobic acrylic. Descriptions such as “hydrophobic-coated” and “hydrophobic acrylic” therefore need to be read carefully.

Material is separate from optical design. Either family can be used in lenses that correct astigmatism or provide different ranges of focus. Our lens implant guide explains these choices; the overview of implants available in Australia describes the wider range.

What are the main advantages and disadvantages?

Is capsule clouding the same as a cloudy implant?

No. Posterior capsule opacification (PCO) is clouding of the thin membrane behind the implant. The implant itself can remain clear. Remaining lens cells grow across this membrane after cataract surgery.

Trials and a large UK cataract registry generally favour hydrophobic acrylic for reducing PCO and the need for Nd:YAG laser capsulotomy. The implant’s sharp posterior edge, continuity of that edge, contact with the capsule and surgical factors also matter. Comparing two lenses does not isolate the material alone.

If PCO is causing symptoms, YAG posterior capsulotomy can open the cloudy membrane. It cannot remove calcium embedded in an implant. Before laser treatment, it is important to establish exactly where the opacity lies.

+

What is implant calcification?

+

Calcification means deposits of calcium-containing mineral form on or within the artificial lens. They can scatter light and cause haze, glare or reduced contrast. This is different from the original cataract returning: the natural lens has already been removed.

Two broad patterns are recognised. Primary calcification is associated with the implant material, manufacture or packaging, sometimes involving particular production batches. Secondary calcification develops in an altered environment inside the eye, including after certain further operations. An explanted lens may need laboratory examination to establish the deposit’s composition.

If calcification substantially affects vision, replacing the implant may be necessary. Drops and YAG laser generally do not clear mineral deposited within the acrylic. Mild changes without meaningful symptoms may instead be monitored.

What happened with older Oculentis lenses?

Certain historical Oculentis/LENTIS lenses developed delayed calcium deposits. These implants had a hydrophilic acrylic core with a hydrophobic surface. A 2017 recall notice covered affected lenses with expiry dates from January 2017 to May 2020; these are packaging expiry dates, not the dates they were implanted.

A large retrospective UK study published in 2026 followed records for 47,171 LENTIS lenses implanted from January 2010 to July 2015, with opacification identified up to January 2024. It recorded 2,426 opacified lenses, or 5.1% of that historical cohort. The average interval to diagnosis was about seven years. Most implants were multifocal.

That finding is a meaningful warning about those particular historical lenses. It is not a 5.1% risk for every hydrophilic implant, every Oculentis lens or current hydrophobic acrylic lenses. Retrospective follow-up also cannot guarantee that every case was captured. Patients with an old implant should check the exact model and manufacturing details rather than infer risk from the brand name alone.

Can retinal or corneal surgery with air or gas cause clouding?

There is a documented association, particularly with hydrophilic acrylic implants. Calcium deposits have been confirmed in lenses removed after vitrectomy with gas used to support a retinal detachment or macular hole. This has occurred in implants from several manufacturers, including hydrophilic lenses with a hydrophobic surface.

Air or gas is also used at the front of the eye to support an endothelial corneal graft. These operations include DMEK and DSAEK, which replace the cornea’s inner cell layer. Repeat injections of air or gas, called rebubbling, have been associated with greater risk in some studies.

+

The proposed explanation involves contact with air or gas, changes in the implant’s hydration and the chemical environment, and sometimes inflammation. It is not simply that a bubble scratches the lens. In retinal surgery the bubble usually sits behind the iris, but may reach the front of the eye; direct contact and the surrounding changes are relevant.

The risk is difficult to quantify. One DMEK series found calcification in 14 of 564 eyes (2.5%); another reported a higher frequency in a different group. Case series of affected retinal patients cannot establish the chance for everyone undergoing surgery. Occasional cases have also been reported in lenses described as hydrophobic, so lower susceptibility does not mean guaranteed protection.

When gas-dependent retinal surgery or endothelial graft surgery is foreseeable, this evidence supports discussing a suitable bulk hydrophobic acrylic implant. For someone who already has a hydrophilic lens, necessary retinal or corneal treatment can still proceed with individual planning; preventive lens exchange is not automatic.

What are glistenings, and do modern hydrophobic lenses still develop them?

Glistenings are tiny fluid-filled spaces within the lens material. Under the examination light they look like fine sparkling points. They are different from calcium deposits and from the haloes caused by some optical designs.

Older hydrophobic acrylic formulations, particularly some older AcrySof lenses, often developed glistenings. More glistenings can increase light scatter, but visible glistenings do not necessarily mean poorer vision. A nine-year comparison found more glistenings in its hydrophobic lens group without a corresponding relationship to measured visual acuity or contrast sensitivity.

Polymer chemistry and manufacturing have since changed. Three-year randomised comparisons of newer hydrophobic lenses show that glistenings can be markedly reduced and that visual performance can remain good. Those results apply to the tested models and follow-up periods. “Glistening-free” may describe a grading threshold; it should not be read as a lifetime guarantee that no microscopic change can occur.

Surface or subsurface light scattering is another material change that can produce a whitish appearance in some hydrophobic lenses. Its significance depends on severity and symptoms. The number of letters read on a chart alone may not capture a patient’s difficulty with glare.

Are there other material differences worth considering?

Inflammation: laboratory and older clinical work found favourable surface-cell responses with some hydrophilic implants. However, surface findings do not establish that every hydrophilic lens causes less inflammation or is preferable in uveitis. A recent randomised uveitis trial found no significant six-month inflammatory or visual advantage between its tested materials.

Optics and reflective symptoms: refractive index and colour dispersion vary with the polymer. A higher refractive index can allow a thinner optic, while a lower-dispersion material can reduce separation of colours. These are engineering properties, not proof of better everyday vision. Lens edge, optical design, pupil size and position influence unwanted shadows or other light phenomena; material alone does not predict them.

Silicone oil: oil used in some retinal operations is different from gas. It can adhere to an implant and affect clarity. Older laboratory comparisons found less oil adhesion on some hydrophilic lenses than on hydrophobic acrylic, with silicone implants showing the greatest adhesion. These were tests of specific lenses, not patient risk percentages. Hydrophobic acrylic should not be described as oil-proof; a silicone implant is also a different material from either acrylic family.

Handling and stability: softness, unfolding speed, surface adhesion, the supporting arms and the delivery system influence insertion and positioning. A material’s advantages for handling do not establish superior long-term vision or astigmatic stability across all models.

How should patients weigh the choice?

Ask about the exact model and polymer, not just whether the lens is “premium” or has a hydrophobic surface. Hydrophobic acrylic usually offers a persuasive balance when reducing later capsule clouding and avoiding hydrophilic calcification are priorities.

The discussion should also consider the eye’s cornea and retina, possible future surgery, optical design, astigmatism, the desired range of focus and the model’s clinical record. Many hydrophilic lenses function well; their useful properties should be weighed against their particular risks.

Both families have been used for decades. The uncertainty concerns individual formulations and newer models, especially when complications can appear many years later. Short-term good vision and accelerated laboratory ageing are useful evidence, but they cannot prove that a lens will remain unchanged for life.

+

What if I already have a hydrophilic lens or a cloudy implant?

A clear, well-functioning lens does not need replacement simply because it is hydrophilic. Keep your implant card or operation record and tell future retinal or corneal surgeons which lens is present. If you notice gradual deterioration, arrange an examination: the cause could be the capsule, the implant, the cornea, the macula or another problem.

A lens exchange is a more involved operation than the original cataract surgery. A previously opened posterior capsule can make exchange more complex and may require vitrectomy or a different method of supporting the replacement. When opacity appears to be within the implant, review it before proceeding with YAG laser. Our lens exchange article explains the options and risks.

For a recalled historical model, the treating surgeon can check the recall’s exact scope and recommend appropriate monitoring. A recall does not by itself mean an implanted lens must be removed.

What should optometrists look for and communicate?

• Record the model, implant date and, where available, batch details. Check whether a “hydrophobic” description refers to the surface or the bulk material.
• Ask about vitrectomy with gas, DMEK/DSAEK and rebubbling, and note the timing of deteriorating vision.
• Examine the implant as well as the posterior capsule. Pupillary-zone granular haze or diffuse changes within the optic warrant review; a normal-looking capsule does not exclude material opacity.
• Document visual acuity, refraction, symptoms and slit-lamp findings. Consider corneal and macular causes alongside the implant, with imaging when indicated.
• Refer suspected implant opacity for ophthalmic assessment before routine YAG capsulotomy, and communicate any previous capsulotomy.

These findings prompt assessment; they do not establish the deposit’s chemical composition or the need for exchange by themselves.

When does a change in vision need urgent assessment?

Seek urgent eye assessment for sudden vision loss, increasing pain or redness, new flashes or floaters, or a curtain or shadow across the vision. These symptoms should not be attributed to gradual implant clouding without examination.

Contact your treating surgeon or an urgent eye service promptly. If you cannot obtain timely care, attend an emergency department. Do not wait for a routine appointment or use an online enquiry form for urgent symptoms.