Oculentis lens exchange: An expert guide on restoring clear vision

In this detailed article, we hear from Mr Stephen Lash, a prominent consultant ophthalmic surgeon on opacification issues faced by patients with Oculentis multi-focal lenses. The leading specialist discusses when lens exchange is required, potential complications to be aware of, and the techniques involved in surgery. With excellent safety and success rates, Mr Lash has performed over 160 Oculentis lens exchange procedures and shares this wealth of experience and expertise in this informative guide for patients.

What is an Oculentis lens exchange?

Oculentis lenses were multi-focal lenses which were used in treatment from around 2010. We became aware that the certain batches of lenses were opacifying – i.e. they were going cloudy, and a field safety notice was released in 2014 warning of this complication. At the time, it was believed that the problem stemmed from the way the lens was stored, after manufacture, in glass bottles. Many patients have been affected. Oculentis lens exchange refers to the procedure required to replace the Oculentis lenses which have become cloudy.
 

When is Oculentis lens exchange necessary?

If you have had Oculentis lenses put in and you have no problems, then no action is required. Some people, however, are developing opacification and only certain batch numbers appear to be affected.

If you are developing opacification, you will notice that with certain light you see well but if you come into strong light, such as sunlight from the side or above or front-facing headlights at night, you may get significant glare. This may appear like a mist over the eyes or like looking through a dirty window. This can also reduce contrast, making tasks difficult in poor light.

The most common misdiagnosis made for this problem is posterior capsular opacification. Very commonly after cataract surgery, your capsule will become hazy and in turn, your vision will become less clear. This is treated by laser, which is used to clear an opening in the cloudy capsule. The key difference between thickening of the capsule and opacification of the lens is that you often have very good vision in certain lighting conditions with opacification, whereas with capsular opacification the vision is usually poor.
 

How safe is Oculentis lens exchange? What are the potential complications?

If you have had a faulty lens implanted and you are experiencing problems with it day to day, it is worth discussing removal of the lens.

I've now performed over 160 Oculentis lens exchanges. They are technically difficult to remove but like all surgery, the technique and decision making has improved over time. You should only really have surgery if the lenses are causing you problems.

The surgery involves removing the lens from the capsular bag and putting a new lens into the bag. The new lens is very likely to be a standard single vision lens NOT a multifocal lens. All surgery comes with risks and benefits. This is very safe surgery but there are, of course, some potential complications. The most common complication I've seen is in predicting the power of the lens. This is because we are taking a lens out of the eye and putting a new lens in. When we calculated the lens the first time, we measured the curve and length of your eye and made a very good guess at what was needed. However, because you are a biological system and the lens that we removed has a thickness to it and the plastic lens is thin, that lens can sit at slightly different points within the eyes and this can change its effective power. That becomes even more difficult to predict with a lens exchange.

If you are thinking about safety, the most common issue is that you may need spectacles to get the best quantity of vision. By quantity of vision, I mean reading down the eye examination chart. Having had the procedure done, most people tell me they are very pleased with the improvement in the quality of their vision with the elimination of the global misting with the opacified lens.

There are other complications associated with this procedure, most commonly swelling at the back of the eye, known as cystoid macular oedema, which usually responds to drops over several months.
 

How is this type of lens exchange performed?

I have two techniques that I use to take the faulty lens out. One technique is where the lens is replaced within the capsular bag. In other words, the bag (the bit that holds the lens in place) is very secure and strong and so as I remove one lens, the bag remains intact and I can put a new lens inside that bag.

Unfortunately, in around 60 per cent of the cases I've operated on, the bag becomes loose and can fold or become unstable. In those situations, I would fix the lens in the white of the eye by a technique called scleral haptic fixation. This involves putting the arms of the lens in the white of the eye.

The results of both techniques are fairly similar in terms of outcomes but the rate of swelling at the back of the eye is higher if I have to do the scleral haptic fixation, at around 5%. Having recently audited my first 100 cases, I have slightly changed the technique to try and reduce that swelling rate by making a small hole in the iris at the time of surgery. This seems to be working well thus far.

In terms of outcomes, both techniques give very similar results, with unaided vision on average just better than driving standard with the scleral haptic fixation and slightly better than driving standard with lens exchange, being just off 2020 vision. On average, people get back driving vision after the surgery, but spectacles may be required to improve it fully.

However, very few of my patients have actually needed to get spectacles because their other eye (which usually has a different batch) still has the multi-focality. Very interestingly with this technique (more so with the scleral haptic fixation than the direct lens exchange), around 25 per cent of patients actually get a multi-focal type outcome. I define that as unaided driving vision and unaided reading vision, which is a great result and probably due to the surgical technique which creates a certain shape in the eye, thus giving the benefit of multi-focality.
 

What happens after the faulty lens or lenses are taken out?

Once the lenses are taken out, we no longer send them back to the manufacturer. You will need to know your batch number if you're going to come in and have surgery but your supplier (whoever did your surgery), will be able to supply that to you.

After surgery, we put the new lens in and I see you for follow up a couple of times – usually at two weeks and four months - to make sure all is well. For the vast majority of patients, those two visits are all that is required, but in some people, especially those who experience swelling, multiple visits are required. Very occasionally, we get significant complications that need to be dealt with. For instance, in rare cases the cornea can become quite cloudy after the surgery and corneal surgery is needed to fix this.

So far, I haven’t seen any cases of infection but this is also a risk - around one in a thousand - which can cause significant loss of sight. For the vast majority of people, however, after two visits and they can get back to normal life.
 

How long does it generally take to perform an Oculentis lens exchange?

The surgery is carried under local anaesthetic with some sedation. Most people who've had cataract surgery will have had drops in their eyes for anaesthetic whereas I use a local anaesthetic injection. The eyes are more densely anaesthetised and cannot move. Often I will have an anaesthetist with me and they can give you some sedation into the vein.

Surgery will take around 15 to 20 minutes if it's a simple lens exchange, where the lens comes out the bag and new lens goes in the bag.

If we have to go on to perform scleral haptic fixation, then I would need to remove the jelly of the eye, known as vitrectomy, and then place the lens in the white of the eye. This will take around 30 to 40 minutes to complete. Fortunately, it is completely comfortable surgery with very little in the way of pain afterwards.



If you are concerned about clouding of your vision or sight problems related to Oculentis multi-focal lenses, you can schedule a consultation with Mr Lash by visiting his Top Doctors profile.