Cataract after vitrectomy or silicone oil: why it appears, and what is different about the operation

"I had retinal surgery a year ago, and my vision improved afterwards, then it started getting worse again. The doctor told me it's a cataract. Did my retinal surgery fail?" This question comes up often, and the answer is usually no. Cataract is one of the most common things to happen after vitrectomy, and in most cases it is separate from the success of the retinal surgery itself. But cataract surgery in this eye has some special features, and that is what we explain here.

Why does a cataract appear after vitrectomy?

After vitrectomy, a particular type of cataract, clouding of the center of the lens, develops faster than usual. In a study of patients operated on to remove a membrane from the macula, a cataract became visually significant, or had already been removed, in 80 out of every 100 operated eyes, compared with 24 out of every 100 of the patients' other eyes (Cherfan et al., 1991).

This depends mainly on age. In another study, cataract developed about six times faster after surgery in people over 50 than in younger people, and also faster when gas was used (Thompson, 2004). In people with diabetes, however, the need for cataract surgery after vitrectomy was lower in one study (Smiddy and Feuer, 2004).

So if you are over 50 and your eye still has its natural lens, you are likely to need cataract surgery in the years after your retinal surgery.

Is the poor vision caused by the cataract or by the retina?

This is the most important question before surgery. The disease that led to the retinal surgery may itself limit final vision, even after the cataract is removed (Do et al., 2013). So before surgery we assess the macula and retina by examination and optical coherence tomography (OCT), so that we can predict realistically what cataract surgery can add.

What is different about cataract surgery in this eye?

The operation itself is the same phaco operation we explain in our article on cataract surgery, but an eye that has had a vitrectomy sometimes behaves differently during surgery:

• Fluctuating depth of the front chamber: the absence of the vitreous, and sometimes weakness of the fibers that hold the lens, can make the front part of the eye deepen and shallow unusually during surgery, which needs special techniques to manage (Cheung and Hero, 2005).
• Deposits on the back of the lens capsule, which were among the most common difficulties during surgery in these eyes (Chang et al., 2002; Hocaoglu et al., 2016).
• A higher chance of some complications during surgery. In a large series of more than 500 eyes, a tear in the back of the capsule occurred in about 5.5%, part of the lens dropped backwards in about 3.3%, and weakness of the lens fibers in about 2.3% (Hocaoglu et al., 2016).

On the other hand, a smaller study found no clear difference in surgical difficulties and complications between these eyes and eyes that had not had retinal surgery (Chang et al., 2002). In other words, the operation is feasible and its results are usually good, but it needs preparation for these possibilities.

Why might the glasses prescription not turn out as expected?

Before any cataract operation, we calculate the power of the implanted lens from precise measurements of the eye. In eyes that have had a vitrectomy, this calculation is less accurate. In a study of these eyes, the result after surgery varied and was more long-sighted than the different formulas had predicted, and the researchers advised telling patients about this in advance (Lamson et al., 2019).

In eyes that still contain silicone oil, measurement is harder still, because the oil changes how sound waves pass through the eye. Modern optical measurement was more accurate than ultrasound measurement in these eyes (Rajurkar et al., 2022). So the surgeon takes care to use the right measurement method, and the patient may need glasses to correct a small difference after surgery.

Are the two operations sometimes done together?

Yes. In some cases cataract surgery is combined with the retinal surgery in one session, or with removal of silicone oil. In an analysis of several studies of patients with macular hole, combining the two operations gave results similar to doing them in two stages, in vision improvement, hole closure and complications (Liang et al., 2024). The decision depends on the state of the lens, the patient's age, and the type of retinal disease. We explain silicone oil and its removal in our article on silicone oil in the eye.

What can I expect after surgery?

Cataract surgery in these eyes gives good results in most patients. In one study, about 77% of patients reached a good level of vision (20/40, or 6/12, or better), and the most important factor limiting the result was the original retinal disease (Chang et al., 2002).

A common finding after surgery is posterior capsule opacification: a film forming behind the implanted lens months or years later. It occurred in about a third of eyes in the large series mentioned above, and was more common in younger patients (Hocaoglu et al., 2016). It is usually treated with a simple laser in the clinic.

Questions patients often ask

Does a cataract mean my retinal surgery failed?

No. A cataract appears after vitrectomy in most patients over 50, even when the retinal surgery has been completely successful (Cherfan et al., 1991; Thompson, 2004).

Should I wait until my vision is very poor before the operation?

There is no need. The operation is done when the cataract affects your daily life, or when it blocks the doctor's view of the retina during follow-up.

Can I choose a multifocal lens?

That depends on the state of your macula and retina, and on how accurate the eye measurements are. We explain the lens types, and who needs to be cautious in choosing them, in our article on choosing an intraocular lens.

Is there strong evidence on the best timing for the operation?

Not yet. There are no comparative clinical trials that define the best timing or method for this operation in eyes that have had a vitrectomy (Do et al., 2013), so the decision is based on each patient's case.

Summary

A cataract after vitrectomy is expected in most patients over 50, and it does not mean the retinal surgery failed. Removing it is usually successful, but it needs special planning: a careful assessment of the retina beforehand, a cautious calculation of the lens power, and preparation for some difficulties during surgery. Final vision remains linked mainly to the state of the retina. We make sure each patient knows, before surgery, what it can add and what is determined by the original retinal disease.

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