Hydrophobic or hydrophilic lens in cataract surgery: does the lens material matter?

"My surgery report says the lens is hydrophobic, and I heard there is a cheaper hydrophilic lens. Is this a real difference that matters to me, or just company talk?" It is an important question, and the short answer is that the difference is real, but it does not usually show in the first weeks after surgery. The studies that compared the two materials are mainly about what happens over the years: blurring that returns because of capsule clouding, and less common problems linked to certain operations the eye may need later. And the material alone does not settle it; the lens design, especially its edge, also plays a large part.

What do "water-repellent" and "water-loving" mean?

Most foldable lenses today are made from a clear, flexible material called acrylic, and most lenses implanted now are made of water-repellent acrylic (Tavassoli et al., 2024). This material comes in two main kinds. The first is water-repellent (hydrophobic), and its material contains almost no water. The second is water-loving (hydrophilic), and its material holds a proportion of water that makes it softer.

The two names describe the nature of the material, not its quality. Each gives a clear image after surgery if the measurements are right and the eye is healthy. The difference between them shows in how the eye responds to the lens over the long term.

The most important difference: capsule clouding years later

In cataract surgery we remove the contents of the cloudy natural lens and leave its thin outer bag, called the capsule, so that the artificial lens can sit inside it. Months or years later, small cells may grow on the back of this bag, and blurring gradually returns. This is posterior capsule opacification, not a return of the cataract. It is usually treated with a short laser session that opens a small window in the capsule.

This is where the clearest difference between the two materials appears. In an analysis of 9 clinical trials covering 861 eyes, the chance of needing this laser within two years was about 7 times higher with water-loving lenses (Li et al., 2013). In another trial that followed patients for 9 years, the clouding was greater and denser with the water-loving lens, even though both lenses had a sharp back edge (Chang and Kugelberg, 2017).

In medical records from the United Kingdom covering 52,162 eyes, 10.9% of eyes with water-loving lenses needed the laser within 3 years, compared with 2.4% and 4.4% in two groups of water-repellent lenses (Ursell et al., 2018). But this study was funded by a company that makes one of these lenses and was carried out by a company under contract to it, and it was not a randomized trial. So we read its numbers as a general direction, not as a final comparison between particular brands.

To be fair, an older Cochrane review of 66 studies found no clear difference between the materials themselves, while it did find a large difference depending on the shape of the lens edge (Findl et al., 2010). So the newer evidence leans toward water-repellent material, but material is not the only factor.

The edge: design matters as much as material

A lens has an outer edge that may be sharp and square or rounded. A sharp edge acts as a barrier that stops cells from creeping behind the lens. In a recent Cochrane review, the need for laser fell clearly with a sharp edge after 3 and 5 years, about 170 fewer cases per 1000 eyes after 3 years. In the first year, cases were very few in both groups and the difference was not certain (Maedel et al., 2021).

Even between two water-repellent lenses from two different companies, a small difference in the degree of clouding appeared over 3 years. The researchers concluded that the material, the surface finish and the shape of the edge work together, and that none of them alone is enough to prevent clouding (Leydolt et al., 2024). So the useful question is: what is the lens made of, and does it have a sharp back edge? Not the material alone.

Does water-loving material have advantages?

No material is perfect. In an older clinical trial that compared six lenses, more tiny inflammatory cells appeared on the surface of the water-repellent lenses than on the others, but they were mild and had no effect on vision. Water-loving lenses, on the other hand, tended to have capsule cells growing over their surface (Abela-Formanek et al., 2002).

Some water-repellent lenses also show what are called glistenings, extremely small water-filled bubbles inside the material (Werner, 2010). They can look striking on examination, but in most cases they do not reduce visual acuity and do not require the lens to be changed (Kanclerz et al., 2021).

In eyes with chronic inflammation of the iris (uveitis), Cochrane reviewed the available trials and could not determine which material is better, because the studies were small and differed in their methods (Leung et al., 2014).

When does the choice of material matter more than usual?

There is one situation where material matters much more: when the eye later needs an operation in which air or gas is injected inside the eye. These include corneal endothelial transplants and some retina and vitreous operations. Medical reports have described calcium deposits forming on water-loving lenses after these operations, so the lens itself becomes cloudy. This has also been described after some glaucoma operations (Darcy et al., 2019; Werner et al., 2015).

In a study that followed 372 eyes having a corneal endothelial transplant, 12.9% of the lenses became cloudy; this was linked to the type of material, and vision fell in the eyes whose lenses clouded. The researchers advised avoiding water-loving lenses for people expected to need this operation (Lorenzana-Blanco et al., 2023).

So the material may matter more for people who are likely to need these operations later, such as those with a weak corneal endothelium, or a retinal disease that may need surgery with gas. We explain what is different about cataract surgery after retinal surgery in our article on cataract after vitrectomy, and about people with diabetes in cataract surgery in diabetes.

Questions patients often ask

Does a water-loving lens give less clear vision after surgery?

The difference the studies measure between the two materials is mainly about capsule clouding over the years (Li et al., 2013). How clearly you see in the first weeks depends more on the accuracy of the measurements, the correction of astigmatism, and the condition of the eye itself. We explain this in our article on American, European or Indian lenses.

I already have a water-loving lens. Should I worry?

There is no need to worry. If blurring returns because of capsule clouding, laser treatment is usually simple. What matters is to tell any doctor planning an operation on your cornea or retina which lens you have, because it may change some of their surgical decisions (Darcy et al., 2019).

How do I find out what material my lens is made of?

Ask your surgeon, or check the lens card or the operation report, which usually show the lens name and model. This information is worth keeping with your medical papers.

Is a water-repellent lens free of any drawback?

No. Glistenings can appear in it, although in most cases they have no meaningful effect on vision (Kanclerz et al., 2021). And the edge and design affect the result as much as the material (Leydolt et al., 2024).

Summary

Water-repellent material is linked in most of the evidence to less capsule clouding over the long term, especially when the lens has a sharp back edge. Water-loving material is not a mistake in itself, but it carries a higher chance of clouding, and a risk of calcification if the eye later needs air or gas injected. We discuss each patient's likely future needs, such as retinal disease or a weak cornea, before choosing the material, because the difference between the two shows over years.

This information is for health education and does not replace a medical examination.