Presbyopia: A sign you’re not a spring chicken anymore…..

Imagine you had a camera and it stopped focusing. It might take clear pictures in the distance, but up close everything becomes a hazy mess. Well, back goes the camera to the service centre or perhaps it's time to get the next iteration of your favourite DSC or DSLR (or autofocus lens...)

If only we could do the same with our eyes, for this is exactly what happens when the big 4-0 arrives. The lens in our eyes becomes stiffer, and this prevents it from focusing well for both far and near. In short, the eye becomes a fixed focus camera.

In actual fact, the process is a gradual one, and the lens loses its elasticity from as young as the twenties. However, it is in the early 40s when the loss of elasticity reaches such a level that focusing at reading distances becomes a pain. By the time one reaches the mid-fifties to sixties, there is virtually no focusing ability left.

The proper term for this is ‘Presbyopia’, but people may call it ‘old sight’, ‘longsightedness’, Lao Hua in Chinese, or Rabun Tua in Malay.

How it affects different people

How the condition affects you depends on what your existing spectacle power is, and what you normally use to obtain clear vision.

Let’s talk about the simplest situation, that of people who see well in the distance and do not need to wear glasses. (This includes people who have had refractive surgery like LASIK). These people continue to see well in the distance, but find that they have to hold reading material further and further away to keep it in focus. Eventually, it just becomes too tiring to read at arms length and also having to squint forcefully causes significant brow ache. That’s when reading glasses become one’s indispensable companion.

The second situation is of people who are shortsighted, ie they need glasses to see clearly in the distance. Without glasses, these people’s eyes are like cameras with extension tubes fitted. They lose infinity focus but on the other hand can focus at macro distances. Therefore, if they take off their glasses, they can see remarkably well for near even when they reach the presbyopic age group. If they wear glasses or contact lenses for distance, though, they are no different from the people in the ‘normal’ group, ie their eyes have had their extension tubes removed and with the glasses everything nearby becomes blurry too. So for looking at near things, shortsighted people either remove their glasses, or they may get glasses with a reduced distance correction.

The final situation is of people who have real longsightedness. To give a camera analogy, these people’s eyes are like cameras where the lens has been mounted too close to the film or sensor plane. To make an object at any distance clear, some degree of focusing effort needs to be put in. Even for an object at infinity, the lens needs to be focused for closer than infinity for clarity. Because these people have to put in more effort at focusing, they will notice the problem with reading earlier than others. At some point, when they are unable to focus even for distant objects, everything becomes blurry. Distant objects are blurred, and near objects even more so. Many of these people end up wearing bifocal or progressive glasses, because they always need something to clear their vision, whether for far or near objects.

Common myths

I’m shortsighted, so ‘longsightedness’ after the age of 40 will cancel out my shortsightedness

Since shortsightedness is a focusing error related to the length of the eyeball, while ‘old sight’ is a problem related to the focusing ability of the lens, they cannot cancel each other out. A shortsighted person will remain shortsighted no matter how old he or she gets. However, they have the option once presbyopic, of seeing things close up by taking off their glasses/contact lenses.

Once I start to wear reading glasses, my presbyopia/old sight/lao hua/rabun tua will get much worse very quickly. So I’m not going to wear them!

Without wearing reading glasses, many older people manage to get by, by squinting, by reading in very bright light, and by holding things as far away as physically possible. It takes a lot of effort. Once they have the reading glasses, everything gets clearer without having to put in all this effort. They may forget that they used to have to strain very hard to see, so that now, without the extra effort and without the reading glasses everything appears blurry. They may blame it on the glasses, when it was actually due to their overcompensating in the past! In actual fact, the condition slowly progresses, with or without reading glasses. Therefore, I advise my patients to wear the reading glasses if they have to and if they feel easily tired otherwise.

(PS: If the camera analogies don't quite ring a bell, feel free to clarify with me. Unfortunately I'm going through a 'gearhead' phase...)

An overview of cataract surgery lens implants

Cataract surgery involves removing the cloudy crystalline lens of the eye and replacing it with a perfectly clear one. Nowadays, these lenses are usually made of flexible clear plastic materials which can be folded and injected through very small incisions of 1.8-2.75mm in width. Most people are not aware that there are various brands competing in the ophthalmic market, and let the doctor make the decision as to which lens to implant in their eye. All well and good, but have you ever wondered what the factors are, that are taken into consideration when selecting a lens? Were you curious to know why your doctor chose the particular lens that was implanted in your eye?

Let's take a step back, and list the important properties of a lens that is meant to stay in the eye for the rest of a person's life.

1) It must stay transparent

2) It must be optically optimal (in harmony with corneal optics)

3) It must have a low association with posterior capsule opacification

4) It must resist the healing/contraction forces of the capsular membrane in which it sits

5) It must not cause any reaction or inflammation

Simple enough?

Let's take point 1. Current materials in use such as silicone and acrylic polymers do stay transparent for many years. In the past some hydrophilic acrylic materials became opaque after developing calcium deposits in the lens optic and had to be exchanged. Among the current lenses, the concern is increasingly with the development of so called 'glistenings' in hydrophobic acrylic lenses. These are tiny water vacuoles that develop in the lens material and have been shown to cause increased forward light scatter, which can reduce contrast. (Notice the minute white dots in the picture below) Although any hydrophobic acrylic material can have this problem, it has been reported especially in lenses made by Alcon, and these include all Alcon Acrysof lenses that are currently being used including the SN60WF (IQ lens), SN6ATT (toric lens), SN6AD1-3 (multifocal lens) and SND1TT/SV25TT (multifocal toric lens).

To be fair, not all Acrysof lenses get such significant glistenings, but it is disturbing that firstly, we cannot predict which particular Alcon lens will get a more severe problem with glistenings, and secondly, among those who develop the problem the glistenings tend to get worse with time.

Vacuoles/glistenings in a diffractive multifocal lens

Miyata A. Water accumulation in polymers [Japanese]. IOL and RS.2007;21:59-62

The only FDA approved and certified glistening free lens currently is the Envista lens by Bausch and Lomb, which is also made of a hydrophobic acrylic material. Almost all other lenses have some degree of glistening formation after some time in the eye, but none to the same degree as what is seen with the Alcon Acrysof lenses.

What about point 2? For the photographers out there, the term 'aspheric' would ring some bells. It turns out that on average, our cornea has +0.27 microns of positive spherical aberration (at 6mm diameter), so if a lens implant has -0.27 microns of negative spherical aberration, the two would cancel out nicely leaving no spherical aberration and improved contrast sensitivity. This has been borne out in some studies, and the effect is more noticeable in dim light when the pupils are more widely dilated.

The lens implants currently in use today with such a degree of negative spherical aberration belong to the AMO Tecnis range of

lenses. Should everybody switch over to these lenses then? Well,

remember that here we are talking about an average figure, so patients with lower degrees of corneal spherical aberration, or those whose lenses might be expected to centre poorly due to pre-existing factors like weak zonules should have an aberration free lens like the Envista lens instead. The problem is that an off centre lens with any built in aberration (like negative spherical aberration in the Tecnis lens) will cause even more aberrations and blurry vision.

Most lens implants in use today are meant to be implanted in the 'capsular bag'. This is like the 'skin' of the cataract that is left behind, and it is in this thin membranous capsule that the new lens sits, right in the same position as the original cataractous lens. Sometimes the original lens cells grow and form a layer behind the new lens implant, blurring vision again. Although this can be very simply treated with a 5 minute YAG laser posterior capsulotomy, it's much better to avoid it in the first place. To this end, most lenses nowadays have a 90 degree sharp peripheral edge, so that when the capsule shrink wraps itself around the lens implant there is a 90 degree bend in the capsule which stops the migrating cells dead in their tracks.

A lens should also sit in the capsule and conform to the size of the capsule as much as possible. It is known that capsular diameters vary among different people and can be larger in people who are highly shortsighted. Flexible loop haptics (like in the lens shown above) allow the lens to be made with haptics of slightly larger diameter, since their flexibility allows them to be compressed for smaller capsules. Plate haptics (like in the lens shown below), however, are rigid and do not allow this kind of ability to adjust for different capsular sizes. They will unduly stretch smaller capsules, and if they are put into larger capsules they either decentre or may move around inside the capsular bag. Woe also to the capsule that contracts and fibroses with time-they will compress and vault a plate haptic lens, causing a refractive shift, usually in a hyperopic direction.

The last point is important but has usually been taken care of in very preliminary studies, and currently lens materials are very biocompatible. Silicone is currently less commonly used, not because it causes reactions or inflammation, but because if a patient has retinal surgery and injection of silicone oil, this oil will stick to the silicone lens andspoil it.

So, to cut a long story short, which lens would I want in my own eye? (or my dad or mum's eye?)

I would have a look at the 6mm corneal spherical aberration first. If it is highly positive, or there is a large amount of corneal astigmatism, the Tecnis lens would be ideal. If the spherical aberration was low, with little corneal astigmatism, I would go for the Envista lens and be guaranteed of no glistenings. Notice that these lenses are both flexible modified C loop designs. I would avoid plate haptic designs or those with rigid 3 or 4 haptic designs. **Would I have a multifocal lens in my own eye? I think not. Presbyopia is not a nice thing to have, but for me personally I think it would be worse to have to put up with constant halos and poor contrast which is only correctable with another surgery to replace the lens!

**Update 16th February 2015
I found myself having to clarify this last part, which I wrote in 2013, because lately I find that my patients who have had the Symfony lens are turning out to be very happy indeed. The Symfony lens is not a conventional multifocal like the Restor or Tecnis multifocal. Instead, it is called an extended depth of focus lens, where the zone of focus is increased to provide good distance and near vision. The best part of it is that there are very few or no side effects like halos. It may not give the sharpest vision when viewing things very close up, but for many people, the benefits of no side effects far outweighs this slight blurring when looking at very near things. So I think this could be my new lens of choice...

Things you should know about cataract

Cataract is a clouding of the original lens of the eye. It is a problem that becomes more common as a person becomes older. In some studies, >90% of people over 70 years old have some degree of cataract. Cataracts can develop earlier in some people if they smoke, have diabetes, or have very high degrees of shortsightedness (greater than 1000 degrees).

Cataracts usually slowly become denser with time, and there is no medicine or eyedrop which can cure it. 

Fortunately, cataract surgery is now very advanced and refined. It is day case surgery which usually takes 30 minutes or less to complete. During surgery, the cloudy lens (cataract) is removed and a new, perfectly clear lens implant is inserted into the eye.

It used to be said a long time ago that a cataract must be ‘mature’ or ‘ripe’ (right) before it could be operated on. Nowadays, that is not true. A cataract can be operated once it affects a patient’s vision such that they have difficulties in their daily life.

As such, a pilot or someone who drives may be affected even when the cataract is fairly mild, or on the other hand a sedentary person with no specific visual requirements could tolerate a denser cataract.

When should surgery be done?

Once the cataract affects a patient’s vision and daily life, and the vision cannot be improved with glasses, surgery can be considered.

Due to advances in cataract surgery, vision can be very sharp after the operation and any existing spectacle power (long or shortsightedness, or astigmatism) can be reduced to allow for good distance vision without glasses. The spectacle power after surgery is in fact customizable, so if a patient desires good reading vision without glasses, he or she could also be intentionally left mildly shortsighted.

Multifocal lens implants do in fact exist and can provide good distance as well as near vision in the operated eye. However, by splitting the light into 2 focus distances, they reduce contrast as compared to normal monofocal lenses and also give rise to halos and other visual disturbances especially in the dark. These visual disturbances are permanent and cannot be corrected with glasses. As such, many patients who want to reduce their dependence on reading glasses after cataract surgery would do better with monovision using normal monofocal lenses.

Monovision involves using lenses that make one eye focus for distance, and the other mildly shortsighted to focus for near. In this way, the 2 eyes working together enable good distance as well as near vision. Patients with monovision still occasionally need glasses, such as when driving at night or when reading fine print for long periods of time. However, they do not experience the reduced contrast or halos that patients with multifocal lenses experience.

Is there such a thing as ‘laser cataract surgery’? For many years now, cataract surgery has been performed using ultrasound to break up the cataract, so that it could be removed through a very small incision of 2-3mm. This is the current gold standard.

In the last few years, a special laser called a femtosecond laser (above) has been created to perform a few steps of the cataract surgery. It is not possible to do the entire surgery with this laser, and it only helps the surgeon to perform several parts of the surgery. At this time, using the laser requires more time than standard surgery, costs more, may cause extra bruising around the eye, and has not been shown to have any better outcomes than the standard method of phacoemulsification using ultrasound. We have not found this laser to be useful although advances in technology in the future may change this.

LASIK surgery-Spectacle freedom with precision laser treatments

Around the world, millions of people have undergone LASIK surgery. It is a very effective procedure, which uses a laser beam to reshape the transparent covering at the front of the eye called the cornea. LASIK was introduced in the late 1990s, and essentially involves creating a very thin ‘corneal flap’, and then using a special ‘excimer’ laser on the cornea under the flap.

The LASIK procedure

Although LASIK is a very successful procedure, many people are concerned about undergoing surgery. Some patients have reported problems such as difficulty seeing at night and dry eyes after surgery. There is the potential of leaving behind some of the spectacle power that was to be treated, and a very small risk of infection.

Before Surgery

Such issues are of foremost importance at Jerry Tan Eye Surgery. Prospective patients undergo a comprehensive assessment to check their spectacle power, corneal shape and general health of the eye. Spectacle power is checked both without and with special eyedrops which relax the muscles of the eye so that the reading is as accurate as possible. Once the assessment is complete, careful planning of the procedure is performed.

The LASIK Procedure

Surgery at Jerry Tan Eye Surgery is normally performed one eye at a time. This enhances safety because there is no chance of infection in both eyes at the same time, even though the risk of this happening is extremely small. Furthermore, it allows fine adjustment of the treatment for the second eye, for a more accurate result.

The traditional method of creating a corneal flap made use of a special blade called a ‘microkeratome’. However, the corneal flap that was created was sometimes uneven, resulting in less optimal outcomes. At our clinic, most cases now have their corneal flaps made by a special laser - the femtosecond laser. It creates a series of bubbles in a perfectly uniform plane in the cornea. This allows a flap to be lifted, much like how a stamp can be torn in a straight line. The resulting flap is much more even in thickness and diameter. Older femtosecond lasers worked very slowly, but the iFS laser at Jerry Tan Eye Surgery creates corneal flaps in 10-15 seconds, minimizing patient discomfort while ensuring better vision after surgery.



How a femtosecond laser creates a corneal flap

The iFS femtosecond laser





After a corneal flap is created and lifted, an excimer laser is used to reshape the cornea. Modern lasers work very fast, and the new Schwind Amaris laser at Jerry Tan Eye Surgery works at 750 times a second. This means that 100 degrees of short-sightedness is corrected in 1.5 seconds. The Amaris laser also tracks eye movements at 1050 times a second in 6 dimensions, ensuring very accurate placement of the laser treatment. For most patients, the actual surgery takes a surprisingly short time in comparison to the time spent on assessment and planning.

Our Results

LASIK results

 At Jerry Tan Eye Surgery our results show that for patients with between 100-700 degrees of shortsightedness, 89% achieved perfect vision (6/6) or better. 55% achieved better than perfect vision.  After LASIK, 84% achieved refraction within 25 degrees of 0, and 97% were within 50 degrees of the intended final power.

Customised PerfectShape® LASIK

In order to avoid night time glare and haloes after surgery, we have developed ‘PerfectShape®’ LASIK at Jerry Tan Eye Surgery. In most traditional ways of performing LASIK, the cornea becomes more curved at the sides after treatment, and this causes poor focusing of light in the dark, when the pupils of the eye become big. PerfectShape® LASIK preserves the natural corneal contour as much as possible while using special corneal maps to guide the laser to smooth out any unevenness of the corneal surface. With PerfectShape® LASIK, night vision was the same or better after LASIK in 90% of our patients, which is remarkable considering that only a few years ago standard LASIK was causing glare and halos in many patients. In fact, PerfectShape® LASIK can be used to reduce night vision problems in many patients who had their LASIK done with older lasers.

A common problem encountered by LASIK patients after surgery is dry eyes. This is related to a disturbance of the eye’s surface caused by surgery. While it normally improves over several months as the eye heals, it can cause blurred vision and eye irritation. In our practice, this problem is less serious because we temporarily plug one of the tear drainage channels. This helps preserve the patient’s own tears on the surface of the eye.

Patients who are older than 40 years of age and undergo LASIK will have good vision for things far away, but near vision is not as good. This is due to presbyopia or ‘old sight’ (rabun tua). This cannot be cured by LASIK. We believe that the best way to reduce the need for reading glasses is ‘monovision’, which means that the LASIK is performed so that some shortsightedness is purposely left behind in one eye. Although with monovision only one eye has clear vision for distance and the other eye has clear vision for near, when both eyes are open all distances are generally sharp.

In summary, LASIK as a method for correcting vision continues to be refined, leading to better outcomes and fewer side effects for patients. Femtosecond laser corneal flaps and customised excimer treatments with the latest excimer lasers bring us closer to the goal of giving perfect vision to all our patients. The future of refractive surgery will bring further innovations, however, they will have to be compared to the gold standard which is current LASIK surgery.

Contact lens FAQs

Problems such as shortsightedness have become so common in Singapore that by 12 years of age, about 60% of children are already wearing glasses. Although spectacle wearing is effective and safe, they are not always the most convenient of things to use.

At my clinic, we often come across patients who are either keen to start wearing contact lenses or are already wearing them but have some nagging questions about them that they just thought of. Hopefully this post, which is in a Q+A format, will help to answer those queries.

1. Can my contact lenses get lost in my eyes?

Contact lenses cannot be lost in the eyes, because there are natural pockets at the side of the eyes which prevent the lenses from going further backwards. However, they may sometimes slip off the cornea onto the white part of the eye. If this is noticed, you may reposition it yourself, or see an eye care professional for help.

2. If I’m playing soccer and the ball hits me near or on my eye, will my lenses break or tear in my eyes?

Direct impact by the soccer ball onto the eyeball will cause injury of varying severity depending on the force of the trauma. A soft contact lens will not generally break or tear due to its flexibility. A hard contact lens could theoretically break although that is also very unlikely due to the softness of the surrounding tissues. What happens more commonly is the lens is knocked or rubbed off the eye. Surface abrasions of the cornea may be caused as a result.

4. I want to wear coloured lenses to look different sometimes... Will these lenses damage my eyes?

Coloured or tinted lenses are available from major manufacturers such as Cibavision. These are generally safe to use but like all contact lenses should be dispensed only after fitting by an eye care professional. Buying these lenses from internet sources, or from manufacturers with an unknown reputation risks severe damage to the eye from problems such as infection, irritation from chemicals in the soaking solution, or poorly fitting lenses.

5. I heard that I could catch Acanthamoeba infection by swimming without removing my contact lenses. This parasite can burrow into my eyes and make me blind. Is this true?

Acanthamoeba is a one-celled protozoan parasite that is found in many places in our environment, including tap water. If contaminated water from the swimming pool enters the eye, Acanthamoeba can stick to the contact lens and establish an infection on the surface of the eye. If not treated, a severe corneal ulcer can develop causing blindness. In general contact lenses should be removed before swimming and they should not be cleaned with tap water or home made saline to avoid this infection.

6. I have no access to saline solution and even tap water. There is a problem with one of my lenses (the edge has curled inwards slightly and is causing me pain). What can I do? Can I remove the affected lens and re-wet it with saliva?

The best thing to do is to remove the contact lens and discard it. Saliva should not be used because the mouth is filled with bacteria and using saliva is going to contaminate the lens, thereby making it very likely for a corneal infection to occur.

7. I fell asleep overnight with my lenses on. Will they get stuck to my eyes?

Sleeping with contact lenses on for any length of time raises the risk of infection and should not be done for any length of time. Even without an infection, lens adherence or sticking to the eye is very common after sleeping with them on and is due to a combination of dryness and the pressure of the eyelids. This sticking is not permanent, and if it happens, the wearer should wet the eyes with re-wetting solution or artificial tears, and then attempt to remove the lens after a few minutes. If this cannot be done, then an eye care professional should be consulted for removal of the lens.

8. I use daily disposables. However, I’ve been wearing them continuously for a week (I don’t remove them). How long can I overuse disposable lenses?

It is very dangerous to wear daily disposable lenses in such a fashion. The lenses become coated with deposits and sooner or later an infection develops or the eye becomes red and irritated from the lack of oxygen and deposits. Disposable contact lenses should be changed strictly according to the schedule recommended by the manufacturer.

9. I was travelling overseas when I ran out of saline solution. I used tap water to rinse my lenses instead. After a few days, I started noticing coloured spots on my lenses. What is happening to my lenses?

It is not possible to say with certainty what these spots are but they could be mineral deposits if the tap water was hard (with a high concentration of dissolved substances). Worse, they could even be fungus growing on the contact lens. These lenses should be discarded immediately.

11. Do the new “HD” soft lenses work for people with astigmatism? Can people with severe astigmatism wear such “HD” lenses? Are RGP lenses still preferred for people with astigmatism?

“HD” refers to optimized optics which include aspheric designs but it does not necessarily mean that the lens will have a toric component to correct astigmatism. A person with severe astigmatism needs either a toric soft lens or a rigid gas permeable (RGP, otherwise known as hard) lens. RGP lenses correct astigmatism very well and possibly provide the sharpest vision among the types of contact lenses. However this must also be balanced with comfort issues.

12. I have lazy eyes. Will contact lenses help my condition? What types of contact lenses are best suited for my condition?

Lazy eyes (amblyopia) develop during childhood because a disturbance of vision prevents normal development of the nerve pathways between the eye and brain. Later on in life, vision remains blurred in the lazy eye even when glasses or contact lenses are worn, because the problem has to do with the nerves and brain, and is not related only to spectacle power. If lazy eyes are detected in childhood, the better eye is patched and the child is forced to use the lazy eye to see, with the use of glasses or contact lenses as appropriate. Beyond the age of about 10 years, patching is no longer useful. Older children and adults with lazy eye are now treatable with a revolutionary computer based training program called Neurovision (see http://www.neurovision.com.sg/). This presents customised images to the patient and over a period of several months improves nerve connections and vision even in adults with lazy eye. As such, lazy eyes are not treated by particular contact lenses per se, but the contact lenses or glasses will help with any long/short-sightedness or astigmatism that is present.

One year already

Time flies. It's been one year since I first started posting and it's been a bit like my paper diaries!!

Eye-wise, interesting things have happened. A year ago I posted about Demodex and using Tea Tree oil or systemic Ivermectin to kill them. If you can compound Ivermectin cream that works even better and does not sting.

I have found a few patients with what appears to be seborrhoeic dermatitis and also happened to have lots of Demodex in their eyelashes. Somehow I managed to cure their skin problem which had usually been causing trouble for years. The Ivermectin cream killed the mites in the lashes as well as in the skin and the rash disappeared. This rash was typically erythematous (reddish) macules and sometimes could be slightly scaly. it was often in the brow and nasolabial fold and had not responded to previous courses of steroids and other treatments. In the picture below you can see the rash between the brows and at the side of the left upper eyelid in one patient.

Recently also we have been seeing a spate of microsporidial keratoconjunctivitis. Often the story was of playing rugby or football on a muddy field (it has been raining a lot over the past one month) and getting muddy water splashed into the eye. Gardeners have also been affected. Their eye became red and teary about a week after contact with the contaminated water. On the front surface of the eye (cornea) the patients developed tiny white spots like in the picture below.

So far all our patients have recovered with antibiotic eyedrops. I think the main issue is not to confuse it with viral conjunctivitis and start with steroid eyedrops too early, since this can prolong the infection somewhat. Viral conjunctivitis is usually redder, with more discharge and stickiness in the morning and there is usually no history of contact with dirty water.

The rugby players at Turf City have gotten so familiar with this that they are going to see the doctor, and telling the doctor the diagnosis even before being seen!

Improving visual quality after previous LASIK

About 2 months ago I saw a patient who had LASIK done in another clinic a few months previously. His vision when measured on the reading chart was actually very good-it was 6/6 without glasses in both eyes. However, he was very disturbed by his vision at night. He was unable to recognize faces when the surroundings got a little dark, and vision in such situations was just generally blurred. Before his LASIK, his power was only about 500 degrees short-sighted.

When we did his corneal maps (topography), it was obvious why he had such problems. The previously treated zone was small, and it was also slightly decentered upwards. Our aberrometer shows clearly his predicament. When his pupil is 3mm in diameter (in bright light), you can see the image of the 'E' is sharp. When his pupil enlarges to 6mm, all you see is a shapeless smudge.

Last week I performed topography guided enhancement LASIK for his left eye. A comparison of the pre and post-operative corneal topographies shows that the central blue/green area is now larger. Subjectively, his night vision is much improved and best of all, his daytime vision also improved to 6/4.8 without glasses.

This case highlights an important aspect of LASIK which is often overlooked, sometimes because of the limitations of technology at a particular clinic. And that is-the quality of vision, on top of the spectacle power issues. In this day and age, we aim not just for minimal spectacle power after LASIK, but also the best quality of vision in all situations. There are limitations, such as for those with very high powers, because there will be issues with corneal thickness. But customizing a 'perfect shape' cornea should be possible for all those with low to moderate degrees of shortsightedness and astigmatism, such as in this case.