All you wanted to know: LASIK FAQs

1. What is LASIK?

LASIK is an operation on the front of the eye, the cornea, to correct spectacle power like shortsightedness and astigmatism.

During this surgery, a thin layer of the cornea (the flap) is partly separated and then an excimer laser is used to reshape the front surface of the eye (the cornea). The flap is then replaced in its original position on the eye.

LASIK Part 1: Creating the LASIK flap with a femtosecond laser

LASIK Part 2: Lifting the flap and performing corneal reshaping with the excimer laser

2. Why go for LASIK?

Glasses and contact lenses actually work very well. But, they sometimes get in the wearer's way. Hmm, going swimming? Better get those contact lenses out first, or gingerly get into the pool and make sure the goggles are fitting well with no leaks.

Fogging of glasses can be annoying...

Spectacles can fog up when going from a colder to a warmer place, or when having a hot drink/meal. Plus, the field of view is limited to the spectacle frame, and strong spectacle lenses can cause distortions at the edge of the lenses. That is why a lot of people with high spectacle powers prefer contact lenses.

Having LASIK done is somewhat like having contact lenses built into the eye, so that one does not have to worry about the daily routine of lens wear, the cost of the lenses, or the dryness and allergies that lenses can cause.

For many patients, the best things after LASIK are waking up in the morning to immediate clear vision on opening the eyes, or going to sleep without having to bother about taking out the contact lenses!

3. What is wavefront LASIK?

Although our corneas and eyes look round and smooth, in fact there are little irregularities that cause us to see starbursts around stars. We call these irregularities aberrations.

Wavefront guided LASIK aims to reduce or correct these aberrations ie to improve the focusing of the eye. The benefits of wavefront guided LASIK are more obvious

1. In people whose eyes already have more aberrations before LASIK
2. When seeing things in the dark/at night after LASIK surgery

Some clinics use the term 'wavefront' loosely, to include wavefront optimized treatments and so on. In fact, wavefront optimized is a kind of standard LASIK that does not take a person's own corneal irregularities into account.

True customized treatments are either (ocular) wavefront guided or corneal wavefront/topography guided. Do clarify with your doctor whether your treatment is 'wavefront optimized' or 'wavefront guided', as the former is a kind of standard treatment and the latter is true customised treatment.

To be fair, not everybody needs wavefront guided treatments. People who are lucky enough to be born with few ocular/corneal aberrations would do just fine with wavefront optimized treatments. Also, wavefront guided treatments usually take more corneal tissue, so sometimes for people with thinner corneas, wavefront optimized treatments may also be more appropriate.

4. What is the difference between epiLASIK and LASIK?

epiLASIK involves surgery that uses a special blade to peel the surface layer of cells off the cornea, then the corneal surface is treated with the laser. In epiLASIK, no corneal flap is made. In LASIK, a corneal flap is made with a special laser called the femtosecond laser.

With epiLASIK, only the layer of epithelial cells is scraped off before laser reshaping. As the cells die and are thrown away, the patient has to wait for them to slowly grow back. 

With LASIK, there is a thicker corneal flap that is replaced at the end of surgery. Repositioning the flap means that there is immediately a healthy layer of cells at the end of surgery, so recovery is much faster than epiLASIK or PRK.

Disadvantages of epiLASIK:

1. Without a flap, epiLASIK patients take much longer to recover than LASIK patients as they have to wait for the surface cells to grow over the cornea. The recovery is like PRK, and vision may take several months to get to its clearest level. In comparison, for LASIK vision is very good the next day and often reaches its best level within 2-3 weeks.
2. Also, with epiLASIK there is a risk that the blade may cut deeper than it is supposed to, resulting in an uneven cornea and permanent blurry vision.

That is why I do not perform epiLASIK. If a patient engages in rough contact sports and prefers not to have a LASIK flap, then I would recommend alcohol-assisted PRK (LASEK) or Transepithelial PRK (TPRK).

5. How do I take care of my eyes after LASIK?

Immediately after LASIK, the eyes may feel mildly irritated and vision is misty.

Remember to put the eyedrops prescribed and use a shield to protect the eyes while sleeping. Sunglasses are useful when going outdoors.

One must not rub the eye at all, and avoid splashing water into the eyes. Swimming is to be avoided in the first month. Other sporting activities can be commenced earlier, for example, going to the gym should be fine after 2 weeks.

6. Is it true that the eye never heals after LASIK?

Although the corneal flap does not stick down and heal to 100% of its original strength, it does heal and after 1 month the flap does not shift even if the eye is accidentally rubbed. In fact the flap is extremely stable after the normal recovery period.

The safety of LASIK is attested to in many ways, for example, athletes like Lebron James in the NBA had LASIK done, and NASA allows people who have had PRK or LASIK to become astronauts:
http://astronauts.nasa.gov/content/faq.htm

There is actually an advantage in this feature of LASIK. If at any point some spectacle power creeps back, the LASIK flap can be lifted, and a minor adjustment/enhancement procedure performed. This can be done provided that the underlying cornea is thick enough.

7. What are the upper limits of spectacle power that LASIK can treat?

Depending on the thickness and original curvature of the cornea,

• the maximum shortsightedness that can be treated is about -11 to -12D (1100 to 1200 degrees), 
• astigmatism -5D (500 degrees), and 
• longsightedness about +5D (500 degrees). 

In exceptional cases, higher powers have been treated, but the risks are of a small optical zone causing halos and other visual disturbances, or of regression ie some of the spectacle power comes back.

8. (Update) Is there a lower limit of spectacle power that LASIK treats?

Generally speaking, the lowest spectacle power that I treat with LASIK is in the region of +/-0.50D. With a lower power than that, most patients are not that bothered by the slight blurring of vision.

In special situations, I may treat lesser spectacle powers than that. This applies to patients with irregular corneas, such as after prior refractive surgery or corneal scars, where the measured spectacle power may be low but the visual quality is poor due to what are called 'higher order aberrations'. These patients need special topography guided LASIK/PRK.

9. Who is suitable to have LASIK?

1. People who are between the ages of 20 and 60 are candidates for LASIK if the spectacle power has been stable (no change of 0.5D/50 degrees or more) for a year or more.

2. Younger ladies who are pregnant or breast feeding should wait until the baby is delivered, or until they stop breastfeeding before having LASIK as the hormonal changes may affect their spectacle power and the long term accuracy of the LASIK correction.

3. Patients going for LASIK should not have other eye conditions such as cataracts or glaucoma.

Above 60 years of age, the issue is the possibility of cataract developing in the next few years after LASIK. Cataract surgery is another way to correct their spectacle power, so the effect of the LASIK procedure may have been only for a few years. Occasionally I do perform LASIK for these patients, but only if the lenses in their eyes look very clear on examination.

With glaucoma, the issue is that LASIK thins the cornea, and this can affect the measurement of the pressure of the eye, which is important in glaucoma. After LASIK, the measurements may show a lower pressure than the actual pressure in the eye, however, as long as the eye doctor is aware that prior LASIK has been done, he can make suitable adjustments and the glaucoma can still be treated.

10. What are the side effects of LASIK?

After LASIK, most eyes become temporarily drier during the healing process. This is helped greatly with artificial tear drops and sometimes with plugging of the draining tear channels. Usually the dryness goes away as the eye heals. By 3 months, about 90% of eyes are no longer dry, and by 6 months >95% of eyes are back to normal.

Halos are common in the early period after LASIK. This is due to slight roughness of the corneal surface (and interface) as it heals. Most of this early halo effect will disappear within a month after surgery. Some halos persist after one month, and these are commonly due to other problems, such as an optical zone that is too small, decentered optical zone, or other aberrations and irregularities. If these are persistent, corneal mapping (topography) should be done to see if specialized topography guided treatment might help.

11. Can LASIK treat presbyopia (Lao Hua)?

LASIK cannot actually treat presbyopia. However, there is the option of 'monovision', which means one eye is fully corrected to see distance clearly, while the other eye is made slightly shortsighted so that it can see clearly at near.

Having 2 eyes with slightly different spectacle powers is something most people get used to, and they do not need glasses for most things. Occasionally they may wear distance glasses for certain activities such as driving at night or reading glasses for really close up viewing.

There are some laser centers and machines that offer 'PresbyLASIK'. There are many other names for this kind of treatment such as PresbyMax or SupraCor. This works by trying to give the cornea a multifocal shape. However, most doctors prefer monovision compared with PresbyLASIK, because

1. The multifocal shape can cause poorer distance vision and side effects such as increased halos
2. The multifocal shape often does not last due to the healing process of the cornea
3. The effect is often modest and many patients still need to wear reading glasses in the end

12. Do LASIK doctors go and have LASIK done themselves?

Doctors (including eye doctors) are just like any other group of people). Some of them wear glasses, others wear contact lenses, and some of them have also had LASIK done. One well known LASIK surgeon who had LASIK done himself is Dr Arthur Cummings, and you can read his account of it here.

http://bmctoday.net/crstodayeurope/2014/02/article.asp?f=why-i-chose-to-have-lasik

13. What is the best age for LASIK?

Please see my previous blog post here.

14. Why did the Taiwanese doctor stop doing LASIK?

In February 2012, Dr Ray Tsai announced that he would stop doing LASIK, because some patients developed poor vision many years after their surgery. While the exact problem was not mentioned, he was probably referring to a problem called 'ectasia'. In the past, doctors were not as aware about the signs of corneal weakness, and with older equipment there was a higher chance of making the cornea too weak. In some patients whose corneas became too weak, the normal pressure in the eye caused the weak cornea to bulge outwards. This causes distorted vision and irregular astigmatism.

A large study conducted by SNEC found that the problem in Singapore was rare, occurring in about 8 out of 30000 cases. The risk is probably even lower nowadays, because:

1. Doctors are more aware of the features that are shown by a weak cornea, and these cases rightly are told they are not suitable and do not get LASIK

2. With newer machines like the femtosecond laser to create LASIK flaps of very precise thickness, the risk of corneas getting too thin is minimized

3. There is now 'LASIK Xtra', a way to strengthen the cornea with vitamin B2 and ultraviolet light at the end of LASIK. LASIK Xtra may also reduce the risk of regression (power coming back) in patients with high spectacle power or those with longsightedness

Even if a patient develops ectasia, the process can be halted or stabilized with cross linking treatment, which is like LASIK Xtra but takes a slightly longer time. The important thing is to catch it early. Therefore, if any patient notices that his/her vision is getting blurry after their LASIK, they should get their eyes checked again by their doctor soon.

My blogging journey so far

I wrote my first post back in 2011.

But actually, I hadn't the faintest clue what it was all about. What's there so interesting to write about the eyes? What's the point?

For the first year or two, you will see that I did not post very much. The lack of knowledge fed a lack of motivation, and time just passed me by. Along the way, several things changed.

One of the important things that happened was coming across some really great blogs that served as an inspiration and motivation. They showed what was possible, and helped me to decide what my niche would be: ie what I would write about that would be interesting and different from other eye related blogs.

I decided that while I would still write mostly about ophthalmic topics, I would add more detail in the posts, especially with regard to useful, practical information that is not readily found elsewhere. ie something of an insider's view. I would try to make the posts thought provoking...At least, that's what I aim to do!

I also found that there is a lot of useful information on the web about blogging and what makes it work.

Some pointers for those who might be interested/things that I learned:

1. Post often
This takes a lot of effort, and I find that I can't really post as often as I think I should or would like to. There are many factors related to this, but includes finding suitable topics to write about, and the actual writing process which involves occasional writer's block...

2. Link the blog to social media such as Facebook, Reddit or Google Plus. If one is so inclined, judicious advertising can speed things along, but should never be the main driving force of the blog. As in real life, the quality of a product is what matters in the long run, and advertising efforts will only provide a temporary boost at best.

3. Maintain an online presence on fora and the like. In my line of blogging, I find it useful to go on websites such as Quora, Yahoo Answers and Medhelp sometimes. Looking at the questions asked gives ideas about future blog topics, gives one a chance to help others, and also provides a chance to link back to the blog on relevant topics. It is important not to do it solely for the chance to link back, something which should always be done in context or the poster risks gaining a bad reputation. Actually, even getting involved on non related fora is helpful, as is the occasional blog commenting.

4. Try to adopt a blog friendly writing style. Something that I am not so good at, but involves short, engaging paragraphs, with pictures as appropriate.

5. Read other blogs to keep the motivation going and also keep up to date with what is happening around the topic of the blog. This ties in with finding topics to talk about.

6. If one is getting really good at it, one can plan and schedule future posts. This is much better than getting to the weekly or other interval, and having nothing in mind.

7. Write down ideas that come to mind before one forgets them.

8. Write 'opportunistically' ie when the urge to do so strikes...

Some years ago, the medical director of the Singapore National Eye Centre where I was working at got everybody to be involved in writing a text book on an Asian perspective to eye conditions. It was a huge effort, but it was done, and we can see its worth everytime we decide to turn the pages and check on something. In a similar way to putting pen to paper, putting thoughts in cyberspace are a (permanent) record of things that we thought or did at some point in time, and hopefully will remain useful in some way, long into the future!

Femtosecond laser and cataract surgery-technical post

This post is going to be pretty technical, and for those who find it tough reading and just want to find out more about this new development in  cataract surgery, please email me (poryongming@yahoo.co.uk) or write in the comments section below.

A number of years ago, some laser companies decided to expand the capabilities of femtosecond laser LASIK flap cutters to make them cut at a deeper level. This is based on the premise that you still have to go in and remove the cataract after the laser cutting is done.

In cataract surgery, the cutting bits involve

1. Corneal cuts (both main incisions as well as relaxing incisions)

2. Capsule cuts

3. Nucleus cuts 

Normally/conventionally, the corneal cuts are made with a metal or diamond blade. The front capsule opening is torn manually in a circular fashion by the surgeon. Finally the nucleus is cut (with ultrasound) or chopped (manually).

The femtosecond laser is a good cutting machine, however, cataract surgery also demands removal of the hazy lens material besides cutting, and the removal is still done with a conventional phacoemulsification machine.

The LenSx machine from Alcon

The Catalys machine from AMO

The Lensar machine

The Victus machine from Bausch and Lomb

The above are the currently available platforms for performing laser assisted cataract surgery. Each have their own pros and cons, and it may be worth asking your surgeon about the system he/she is using. 

Is there a difference in result between conventional vs laser cataract surgery? 

I think it is fair to say that any laser can make more uniform, consistent cuts than those made manually. However, there are several lines of evidence which suggest that there is no difference in clinical outcomes between laser assisted surgery or conventional phacoemulsification.

Effect of femtosecond laser-created clear corneal incision on corne... - PubMed - NCBI

		Effect of femtosecond laser-created clear corneal incision on corne... - PubMed - NCBI J Cataract Refract Surg. 2014 Apr;40(4):531-7. doi: 10.1016/j.jcrs.2013.11.027. Epub 2014 Feb 20. Comparative Study; Randomized Controlled Trial; Research Support, Non-U.S. Gov't
		View on www.ncbi.nlm.nih.gov	Preview by Yahoo

Evaluation of femtosecond laser-assisted and manual clear corneal i... - PubMed - NCBI

		Evaluation of femtosecond laser-assisted and manual clear corneal i... - PubMed - NCBI J Refract Surg. 2014 Aug;30(8):522-5. doi: 10.3928/1081597X-20140711-04.
		View on www.ncbi.nlm.nih.gov	Preview by Yahoo

The above two papers show that there are no or insignificant differences between pre and post operative central corneal curvature, which influences surgically induced astigmatism and post-operative refractive predictability. One paper showed differences in the corneal topography immediately overlying the incision, but this is far in the corneal periphery (not affecting vision) and would be expected to settle down with time.

Effect of reducing ultrasound energy

The main aim of reducing ultrasound energy is to reduce corneal endothelial damage, rather than retinal problems. The phaco probe is normally too far from the retina to cause any problems with the ultrasound. It is, however, only millimeters away from the corneal endothelium during surgery.

Even in this regard, the data is mixed. One paper in fact reported greater early endothelial cell loss in laser cataract surgery eyes than conventional phacoemulsification. The other paper showed no significant differences.

Effect of femtosecond laser-assisted cataract surgery on the cornea... - PubMed - NCBI

		Effect of femtosecond laser-assisted cataract surgery on the cornea... - PubMed - NCBI J Cataract Refract Surg. 2014 Sep 9. pii: S0886-3350(14)01099-2. doi: 10.1016/j.jcrs.2014.05.031. [Epub ahead of print]
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Endothelial cell loss and refractive predictability in femtosecond ... - PubMed - NCBI

		Endothelial cell loss and refractive predictability in femtosecond ... - PubMed - NCBI Acta Ophthalmol. 2014 Nov;92(7):617-22. doi: 10.1111/aos.12406. Epub 2014 Jun 2.
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Effect on IOL position and refractive accuracy

One of the papers below suggests better IOL position after laser cataract surgery, and the other says there is better refractive predictability. Interestingly, the difference in post operative mean refractive error is miniscule: 0.12D. And they say the difference was greater in very short or very long eyes, suggesting a problem with the formula they were using rather than the surgery itself.

 Comparison of IOL power calculation and refractive outcome after la... - PubMed - NCBI

		Comparison of IOL power calculation and refractive outcome after la... - PubMed - NCBI J Refract Surg. 2012 Aug;28(8):540-4. doi: 10.3928/1081597X-20120703-04. Epub 2012 Jul 13. Comparative Study
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 Intraocular lens tilt and decentration measured by Scheimpflug came... - PubMed - NCBI

		Intraocular lens tilt and decentration measured by Scheimpflug came... - PubMed - NCBI J Refract Surg. 2012 Apr;28(4):259-63. doi: 10.3928/1081597X-20120309-01. Comparative Study; Randomized Controlled Trial
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There is no study which compares relatively minor problems like conjunctival haemorrhage etc between laser and conventional surgery that I am aware of. Part of the reason I think is that we just don't see some of these things with conventional surgery. Journal editors tend not to want to publish things that are already known...

With regard to one of the other problems cited with femtosecond laser cataract surgery-that of intraoperative miosis (pupil getting smaller), it is something that does not happen in conventional phacoemulsification unless there is IFIS (Intraoperative Floppy Iris Syndrome), related to the use of alpha antagonists for prostate problems. Nowadays, this problem is minimised by doing the lens removal as soon as possible after the laser cutting procedure.

Is femtosecond laser assisted cataract surgery better, or gives better outcomes than, conventional phacoemulsification cataract surgery? I think the jury is still out on this one!

Jumping, twitching eyelids

‘Dr, my eyes are jumping!’ Goes the patient sitting in front of me. In fact, when I have a closer look, I see that part of the lower eyelid of this patient seems to be shivering. For a few seconds, and it stops. And starts again.

This Youtube video shows a pretty good example of common eyelid twitching: https://www.youtube.com/watch?v=sphQNOihpf0

The patient is having one of the most common complaints seen by eye doctors, and fortunately it is also one of the most benign of conditions. There are in fact several types of eyelid twitching, with the most common type called ‘myokymia’. This condition can come and go by itself and often does not need any special treatment, although it can be quite annoying.

There are also other types of eyelid twitching which are more severe. One of them is called ‘hemifacial spasm’, in which one side of the face, and eyelids on the same side, twitches at the same time. If this happens on both sides at the same time, then it is called ‘blepharospasm’. Both of these kinds of twitching can range from mild to severe, with some bad cases of blepharospasm being unable to open their eyes. Fortunately, these cases are very rare.

Causes of twitching eyelids

Myokymia (Common eyelid twitching)

Although the exact mechanism that causes this is not known, common eyelid twitching is associated with the following:

·         Excessive coffee or other caffeine intake

·         Eye strain which may be associated with incorrect glasses prescription

·         Lack of sleep or fatigue

·         Eye irritation, which can be caused by dry eyes or inflamed eyelids/crusty eyelids

Hemifacial spasm

This uncommon condition can be caused by a small blood vessel near the ear that presses on the facial nerve. Other growths or injuries to the facial nerve may also cause this.

Blepharospasm

In blepharospasm, both eyelids blink together and if the condition gets worse, the eyelids may intermittently squeeze tightly together. Most of the time, the cause is unknown, but this condition can be made worse by any kind of eye irritation. It can occasionally also be associated with the use of drugs such as those used for Parkinson’s disease, and prolonged use of sleeping tablets in the benzodiazepine class.

The origin of the condition is probably different from common eyelid twitching, in that for blepharospasm, the problem is likely to come from abnormal activity in the brain cells, rather than from the nerve endings or muscle cells in common twitching.

Treatments for the twitching eyelid

In cases of common eyelid twitching, possible associated factors like a high coffee intake should be looked into and addressed. From an eye doctor’s point of view, specific things to check include the accuracy of the spectacle power and also the presence of any eye dryness.

Dryness of the eyes is a very common problem around the world, and is associated with both our changing activities as well as environment. The wearing of contact lenses, excessive computer or phone viewing, and the presence of dry air in air conditioned environments all make a pre-existing dry eye problem worse. Simple measures include the use of artificial tear eyedrops, and sometimes tear duct plugging can also be very useful.

In persistent cases, sometimes mild relaxant medications can help, such as Lexotan.

Botox

Botox, or Botulinum toxin, is made by a bacterium that used to cause severe sickness in people who ate from spoiled canned foods. However, when purified and used in proper dosages, it has become a very useful medication for many different conditions. Most famously, it is used to reduce the appearance of wrinkles or ‘crow’s feet’ on the face.

Botox works by ‘paralyzing’ temporarily a very focused set of muscles. It can be used for any kind of stubborn eyelid twitching, including all three types mentioned above. However, it is only extremely rarely used for common eyelid twitching.

The effect of Botox lasts for a few months, and as it fades, the twitching may come back again. If this happens, Botox can be injected again. The good news is that with Botox, often with several injections, the muscle that twitches become weaker, so the effect may become more prolonged after several injections.

Side effects of Botox:

Botox in the hands of an experienced doctor is very safe. Mild bruising can sometimes be seen around the injection site. Rarely, if the medicine spreads to affect certain muscles, the eyelids may droop, or it may be difficult to close the eyes fully. The latter can exacerbate dry eyes. Most of these side effects are temporary, and will get better by themselves as the effect of the medicine wears off.

Hemifacial spasm

In some cases of hemifacial spasm, especially where it is getting worse or associated with facial weakness, an MRI scan can be performed to look for any possible pressure on the facial nerve which controls facial movements. If something is found such as a dilated blood vessel, surgery (called microvascular decompression) can be considered but does carry some risks.

Blepharospasm

Blepharospasm can be a difficult condition to treat and is fortunately rare. Initial treatment includes looking for contributing factors such as eye dryness or eyelid problems. Relaxants such as clonazepam or anticonvulsant medications such as carbamazepine can be used, although they do not always work satisfactorily. Botox is very helpful, and in the worst cases, surgery can be considered to weaken the muscles which are having spasms.

Summary

Most cases of eyelid twitching are annoying but harmless. Simple measures that address risk factors like fatigue and excessive caffeine will help. In more stubborn cases, a visit to your friendly eye doctor can help greatly too!

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