What is it like having premium IOLs that correct for near vision after cataract surgery?

Some time ago I was asked this question on the Quora website:
What is it like having premium IOL's that correct for near vision after cataract surgery?

A very relevant question, given that nowadays there are so many lens options to choose from and also different approaches to avoid reading glasses. Here is my answer:

There are several different types of IOLs that give multifocality and good near vision as well as distance vision. I will base my answer on the most commonly used lenses-the diffractive multifocal lenses like the Alcon Restor, the Tecnis Multifocal and the Zeiss trifocal lenses.

The Alcon Restor lens (above), and the AT LISA tri (below) are examples of bifocal and trifocal lens implants, respectively.

These diffractive multifocal lenses have rings etched onto either their front or back surfaces, which split/diffract incoming light rays into two foci. Some newer ones can even split the light into 3 foci. This fact gives rise to several implications.

1. Vision will be clear mainly at 2 (or sometimes 3) distances. For the older +4 Restor and the Tecnis multifocal, the near focus is at about 1 foot. So reading material has to be held quite close.

If it is held further away (say at 3 feet or so-intermediate distance), then it is not so clear anymore. 

Then things much farther away, say 15-20 feet away, start to become pretty clear again. (See the figure below-only the AT LISA tri is clear at intermediate distance)

Note: This is only the case if the surgeon has been very accurate in calculating the lens power/biometry.

Simulated clarity of images at various distances with different multifocal lens implants. The top 3 are bifocals, and the bottom one is a trifocal. Only the trifocal gives pretty good intermediate vision-but at some cost in terms of contrast when compared with the Alcon SV25T0 and AMO ZKB00. (From IOVS 2015;56:3970)

2. Because of the light splitting, there is a drop in contrast compared with a monofocal lens. Patients with multifocal lenses tend to be more sensitive to low light conditions-ie when it starts to get a little dark, they start to feel the drop in vision faster than patients with monofocal lenses. A person with a monofocal lens and reading glasses could read in dimmer conditions than a person with a multifocal lens.

3. The rings on the IOL give rings of light (halos) around light sources. This can be an issue when driving at night because of the halos around car headlamps. Having said this, many patients get used to the halos and do not notice it as much after a time.

Simulated halos around lights from a mutifocal lens

The above of course does not completely apply to the Crystalens or the Oculentis MPlus. The Crystalens is an accommodative lens, which gives somewhat unpredictable results-some patients don't get any near effect at all. 

The MPlus (available in Europe/Asia) has a wedged shaped section on the lens to focus for near. Point 1 above applies to this lens as well. However, although this lens does not give rings around lights, it can still cause 'halos' of a different shape-it is more like a smearing effect in one direction. Occasionally if a patient's pupil is small and not aligned with the lens, the patient may only have a far focus or a near focus and not both.

Last but not least, there is the Symfony lens which I covered in my last post. As mentioned, this is an 'in between' lens, ie in between a monofocal and a multifocal. It has no intermediate vision problems, and less halos than the usual multifocals, but does not give quite as good very near vision.

Currently, I offer patients a choice between a monofocal, an in between lens like the Symfony, and a full fledged trifocal like the AT LISA tri. I believe there is little to no benefit to be gained from using older bifocals such as the Restor and Tecnis Multifocal currently. Exactly which of those 3 choices gets implanted comes after a careful discussion with my patient regarding the pros and cons of each option. (So that we get big smiles all round afterwards!)

Cataract and Cataract Surgery FAQs

In my line of work, I get asked lots of questions about cataracts, quite simply because they are one of the most common causes of blurred vision as one gets older.

Here goes:

1. What are cataracts? Are they a growth in the eye?

Cataracts are not growths.  One of the parts of the eye, called the lens, undergoes ageing processes over the years. A lens, like a camera or spectacle lens, needs to transmit and focus light and therefore needs to be transparent. Unfortunately age causes many lenses to become hazy and this blocks vision, much like trying to look through a dirty window.

2. How do I know if I have cataracts?

The main problem with cataracts is blurred vision. Of course, there are many other causes of blurred vision, such as shortsightedness or astigmatism. Therefore, if vision is blurry, try wearing spectacles first and see if the vision is cleared up.

If so, the problem is probably just spectacle power, or perhaps the cataracts are very mild. Significant cataracts will cause blurred vision even if spectacles are worn. Generally speaking, if vision cannot be made clear with glasses, one should visit the eye doctor to make sure there are no serious eye problems.

3. How does it feel like to have cataracts?

This is related to the prior question. Although we may think that cataracts are just a hazy lens and are the same, in fact there are a few types of cataracts that affect vision in slightly different ways. For example, vision can be clearer under certain conditions, or sometimes patients get double or triple vision.

A yellow nuclear sclerotic cataract

One type of cataract causes the lens to become yellowish (above). This is called 'nuclear sclerosis', and the eye also becomes more and more shortsighted. Patients with this type of cataract may need to increase their shortsighted spectacle power several times a year. On the other hand, long sighted people may find their spectacle power getting less and less, and near vision getting better and better! This is sometimes called second sight.

Another type of cataract causes glare. This means that a person can see reasonably well in the dark, but when there is a bright light shining from in front, vision undergoes a 'white out', ie everything turns bright white and vision suddenly becomes very blurry. This happens with a cataract called a 'posterior subcapsular' cataract.

A very dense, white cataract

If cataracts are neglected for a long time, they can turn white (regardless of which type they originally were). White cataracts are more dangerous than other types, because they sometimes absorb water and swell. A swollen lens can physically block the drainage angle of the eye, or leak proteins which also block the drainage angle. This causes a sharp spike of eye pressure, leading to a type of glaucoma and eye pain. This is the only situation where cataracts are associated with eye pain.

4. What causes cataracts?

As mentioned, most cataracts are due to age related changes in the eye. Proteins break down, clump together, sometimes water is even absorbed into the lens causing to swell.

Besides age, there are other less common causes of cataracts. Certain medicines such as steroid eyedrops or tablets, if taken in high doses for too long a time, can cause cataracts to develop. Diabetes, which results in too much sugar in the blood, also cause cataracts to develop earlier, especially if the blood sugar levels are not controlled properly and become very high for a lot of the time. Cigarette smoking is well known to be associated with earlier cataract development as well. Finally, bad injuries to the eye, such as a direct punch or a hit in the eye can also cause a cataract to develop.

5. How can I prevent cataracts, or can I slow down their progression?

Firstly, any risk factors such as diabetes or cigarette smoking should be addressed. Modifying these risk factors will have the biggest impact on slowing cataract progression.

Secondly, eat a healthy diet full of antioxidants. In general, it is better to get these naturally from green leafy vegetables and colourful fruits, rather than supplements. However, certain nutrients may only be obtainable in large quantities in supplements.

Studies of big groups of people suggest that eating more fruits and vegetables can delay cataract development, but nothing conclusive so far can be said for individual nutrient supplements such as vitamin C.

6. How are cataracts treated?

Cataracts are treated with surgery to remove them, and at the same operation they are replaced by lens implants made of a special acrylic material.

Cataract surgery is carried out under local anaesthesia, and is painless. The hazy lens material is broken up with ultrasound, and then removed through a very small incision about 2mm long. The lens implant can then be folded and injected into the eye through this very small opening.

Recovery is very quick, with most patients seeing very well even on the day after surgery.

Sometimes patients ask me if they should wait until after their holiday to have surgery. I tell them that if time permits, to do it before, as they will enjoy the view so much more!

7. What are the latest advances in cataract surgery?

The most important developments in cataract surgery have to do with how spectacles can be avoided after surgery. Yes, no matter how high the spectacle power before surgery, most of the time spectacle wear can be avoided after surgery. How is that possible?

Focusing of light in the eye depends on the cornea, the lens, and how long the eyeball is. The shape of the cornea can be changed (in LASIK), and the lens power can be changed (in cataract surgery) to reduce or eliminate spectacle power.

A normal spherical Tecnis (AMO) lens

A Toric Tecnis (AMO) lens. Note the dots arranged in a line at the sides of the lens. This allow the surgeon to place the lens in exactly the right position to reduce or eliminate astigmatism after surgery

The Tecnis Symfony (AMO) lens. This is a multifocal lens that is also available in a toric version (right) so it can be used in most patients

Nowadays, lens implants also come in 'toric' versions to correct astigmatism, and there are also 'multifocal' lenses that give good near and far vision to avoid reading glasses after cataract surgery. 

For patients who would like clear far and near vision without glasses, and have astigmatism, there are even multifocal+toric lens implants.

Multifocal lens implants can give halos around lights at night, however, this has been minimised with newer extended depth of focus (EDOF) implants like the Tecnis Symfony (above).

Laser cataract surgery

Some surgeons are now using a type of laser to help to do certain steps of the surgery. They call this bladeless cataract surgery, much like how LASIK became 'bladeless' LASIK.

Unfortunately, using this laser to help with surgery makes the surgery much more expensive and also can result in problems that probably would not have happened if the surgery had been done with conventional phacoemulsification surgery. In the article above, 1/3 of patients had conjunctival haemorrhage, and 1/5 had anterior capsular tags. In 1/3 of patients, the pupil became smaller, making the surgery more difficult for the surgeon and increasing the risk of other complications.

Although this technology may become better with time, and surgeons will become more experienced with using it, currently this is an example of how a 'latest advance' is not necessarily better and in fact has become a kind of marketing tool.

Below is an exchange in the local newspapers in 2013, where the Singapore Academy of Medicine published a response in the Straits Times to counter certain unfounded claims put forth by proponents of the laser cataract surgery procedure:
http://ams.edu.sg/view-pdf.aspx?file=media%5C499_fi_807.pdf&ofile=STForum20130516+-+Traditional+cataract+surgery+remains+%27gold+standard%27.pdf

The story of the Symfony lens

About 2 months ago I was chatting with my parents on Facetime. I had helped my father with his cataract surgery in February/March earlier this year (fortunately everything went fine!) and naturally they were still quite in tune with things happening in this area of medicine.

My mum goes, 'Have you heard of the Symfony lens?'

I went,'Umm, sorry, you mean the Synchrony lens? I've never heard of the Symfony lens.'

Then she went on to point me to the Daily Mail webpage on the Symfony lens:

I was a little taken aback, because there had been no heads up from the company producing the lens implant. (And I was the supposed eye expert in the family too!)

The aforementioned company had previously  bought over the rights to a lens called the Synchrony accommodating lens implant, however, this had been delayed and then from the looks of things, shelved. (after paying a lot of money...)

In any case, this lens didn't look much different from the currently available diffractive multifocal lenses such as the Tecnis multifocal lens. So my mum asks me: 'wah, so this lens can see far and near without having any halos...'. And I went, 'but it has rings, so the patient will have halos...'. And my mum says, 'but that's not what it says in the article!' And so I capitulated. 'I'll just check with the representative tomorrow'. I felt a bit bad, partly because I wasn't able to answer their query but also I wasn't sure if I had inadvertently left them crestfallen after their high hopes about the new lens.

A week later I had the same query from a patient, and so it was that I was a bit more prepared to discuss the lens. Thank god for my mum who surfs the net!

When I asked the company representative about the lens, unfortunately there was not much information to be had. It was only last week that I found out a bit more about the lens. I understand that this is a new lens, but it achieved the CE mark in June and I think companies in this day and age should do more to coordinate the availability of their products, and also the dissemination of information about their products around the world. The thing is, the world has never been a smaller place...

Update 22 October 2014
2 months down, the Symfony lens has finally arrived in Singapore! It is currently in an evaluation phase with limited lens powers available, however, suitable patients can be considered for this lens. I feel that this is a lens which is likely to be better accepted among patients, and also doctors, as it uses a proven platform which should make IOL power more predictable as well.

Update 5 March 2015
My first cataract patients who opted for this lens implant have been very happy, and reported no problems with halos or driving at night. Near vision has also been good, with the ability to read newspapers without glasses.

The Symfony lens is now generally available in Singapore, and is also available in a toric version so that patients with significant corneal astigmatism will also stand to beenfit from this lens. As there are no significant side effects with this lens, I routinely offer it to my cataract patients nowadays, who have no other eye conditions and who desire spectacle freedom after surgery.