What is a Cataract?

As you get older, you will probably find that your eyesight isn’t as good as it once was.  While there are a number of issues associated with the ageing eye, cataract is one of the most common.  Cataracts are part of the normal ageing process, and they affect thousands of Australians every year. Because they are so common, it is not surprising to learn that cataract surgery is one of the most common surgical procedures performed in Australia.

Simply put, a cataract is a clouding of the eye’s lens. The lens is located just behind the iris (the coloured part of the eye). It is approximately the size of a Smartie®, and is responsible for focusing the incoming light onto the retina, which is the ‘camera film’ at the back of the eye. The lens is not visible to the naked eye, and is examined with specialist equipment.

As the lens becomes cloudy, it obscures the incoming light from reaching the retina. Cataract therefore reduces our quality of vision.  Cataract formation is accelerated by UV light, diabetes, short-sightedness, eye trauma, iritis, certain eye surgeries, certain medications and certain medical conditions.

What to do if you have cataracts?

If you’ve been told that you have cataracts then you should see an eye surgeon (ophthalmologist). They will be able to assess your cataract severity, screen your eyes for other diseases, and discuss your treatment options with you.

Surgery is the only treatment for cataracts. Although eyedrops have been investigated as a potential future treatment of cataract, this research is in its infancy and is unlikely to ever be viable.

When is the “right time” to have cataract surgery?

The decision to have cataract surgery is based on your cataract severity and your symptoms. There is no set “cutoff” of when cataract surgery is appropriate, and a cataract does not suddenly become “ripe” for surgery. Some patients will choose to have their cataract treated sooner, and others will choose to wait.

The timing of cataract surgery is a decision made collaboratively with the ophthalmologist and each individual patient.

Factors to consider when deciding if cataract surgery is right for you, include:

    • Your cataract symptoms. However, because cataracts develop slowly, it can sometimes be difficult for an individual to appreciate how their vision has changed. Your ophthalmologist will be able to advise you how much improvement you could expect from cataract surgery.
    • Your cataract severity. Patients with advanced cataract have more to gain than patients with mild cataract.
    • Your visual needs. Patients who do demanding visual activities, such as night driving or prolonged reading, may be motivated to have their cataract treated sooner. Patients who do not do demanding visual activities may be happier to wait.
    • Your surgical risks and willingness to undergo medical procedures.
    • Your age and health. Many patients choose to have their cataracts treated while they are still in good health.
    • The financial investment required to have cataract surgery.

Cataract surgery

Cataract surgery involves removing the cloudy cataract and replacing it with a new, high-definition lens implant. This implant lasts for life and it resets your vision to help you see clearly. If a new lens were not implanted, then vision would be severely defocused and the patient would require thick glasses.

I perform cataract surgery as a walk-in, walk-out procedure in a day surgery. The surgery takes approximately 20 minutes and is performed under twilight sedation. One eye is treated at a time with the two eyes typically scheduled 3-7 days apart.

single vision lens cataract surgery

Standard cataract surgery with a single-vision lens. Excellent distance vision but glasses are required for objects within arm’s length.

Multifocal IOL cataract surgery with Dr Nick Andrew

Refractive cataract surgery with a customized depth-of-focus or multifocal lens. Both distance and near objects are in focus.

Optimal vision from cataract surgery

Optimal vision from cataract surgery requires precise eye measurements, rigorous surgical planning, and the calculation of a customised lens implant tailored to the unique optics of your eyes. This is the art of cataract surgery.

During cataract surgery, your cloudy lens (cataract) is replaced with a high-definition artificial lens implant. This artificial intraocular lens (IOL) lasts for life and it refocuses your vision to help you see clearly. It is custom-selected for your eye to give you the best vision possible.

Before scheduling cataract surgery the dimensions and curvature of your eye must be precisely measured. This is done using a laser scanner (optical biometry) and a high definition camera (corneal topography). The measurements are used to calculate exactly what power of lens the eye requires. If the measurements are inaccurate then the lens selection will also be inaccurate.

I regularly discuss the nuances of this process on my podcast. I constantly seek to improve my patient results, through attention to detail, use of technology and surgical expertise.

the steps of cataract surgery dr nick andrew

STEP 1. Consultation

The purpose of your consultation is for you to understand your eye health and the treatment options available to improve it.

I use advanced diagnostic technology to show my patients the problems affecting their vision. My focus is on education, so that patients have all the information required to make the decision that’s best for them.

My team and I understand that eyecare can be daunting. We want you to feel at ease and we strive to deliver care that is warm, welcoming, and personal.

STEP 2. Choosing the best artificial lens implant for you

This is probably the most important step for you. The lens implant that you and your surgeon choose will make a significant difference to your vision: it will be a part of you, probably forever. You must decide how you want your vision to be after surgery.

During cataract surgery, an artificial lens is implanted to produce focussed vision. These lenses come in many different designs, sizes and brands.  Once your lens is implanted it is challenging (but not impossible) to change it.  Therefore, it is important that your surgeon selects the lens that is best for you.  I use a small selection of highest quality lenses available.

With improvements in technology, lenses are available that have demonstrated improved vision for patients.  These lenses are called multifocal lensesextended depth of field lenses and presbyopia-correcting lenses. They work by different mechanisms and each design has its unique  considerations. Modern lens implants are made from flexible acrylic plastic, and they come in many different designs and sizes.  I use a small selection of the highest quality lenses available.

Every eye is unique and is suited to certain lens implants only. In addition, my patients all live different lifestyles and have different visual needs. This is why selecting the most appropriate lens is a complex process and must be customised for each person. Your vision won’t be as good as it could be if an inappropriate lens is implanted. Cataract surgery, is a once-in-a-lifetime opportunity to reset how you see.

My focus is on both quantity of vision (how far my patients can read down the chart in the distance and at near, without glasses), and quality of vision.

single vision intraocular lens cataract surgery

Single vision lens

Outstanding distance vision but glasses are usually required for most things inside arm’s length (this usually includes the computer, the mobile phone, and reading). Every eye is suitable for single vision lenses

extended depth intraocular lens cataract surgery

Extended depth of focus lenses

Excellent vision for everyday activities. Glasses are usually only required for reading very small print, reading in dim lighting, or reading printed text for prolonged periods (i.e. reading a book).

trifocal intraocular lens cataract surgery

Trifocal lenses

Distance and reading vision can be achieved without glasses. However, quality of vision is reduced and most patients are left with seeing halos around lights. Only a minority of eyes are well suited to trifocal lenses.

intraocular lens distance and reading cataract surgery

One eye for distance, on eye for reading

This is called monovision, or blended vision. It can be well tolerated in certain circumstances. Some compromises of monovision include:

  • Awareness of imbalanced vision.
  • Adaptation time. Some patients adapt to monovision within hours, whereas others can take 6-12 months. Vision can feel strange while adaptation is occurring
  • Reduced depth perception.
  • Discomfort wearing glasses (if glasses are required).
  • Blurred vision when quickly looking towards the side of the reading eye. This might occur when checking your blind spot while driving. Most patients quickly adapt to this problem by learning to turn their head more.
small aperture intraocular lens cataract surgery

Small aperture lenses

These lenses function like a pinhole. They are usually reserved for patients with severe corneal disease.

STEP 3. Getting the eyes ready for surgery

The surface of your eye needs to be as smooth and healthy as possible. All pre-existing dry eye needs to be treated. This improves your recovery following cataract surgery, and most importantly, it improves the quality of eye measurements obtained by laser scanners. I am very proactive about treating dry eye before cataract surgery, as this improves my patients’ vision, comfort, and speed of recovery.

STEP 4. Eye Measurements

The dimensions and curvature of your eye must be precisely measured. This is done using a laser scanner (optical biometry) and a high definition camera (corneal topographer). The power of the lens implant your eye requires is calculated using these measurements.

STEP 5. Calculation of Lens Power

There is special lens calculator software which will takes your eye measurements and determines the best lens power for each eye. Of the wide range of lens calculators available, I use the most sophisticated “4th generation calculators”, with my own computer algorithm.

Obtaining perfect measurements and selecting the best possible lens for each eye is fundamental to premium cataract surgery. I have published scientific research articles on this process.

STEP 6. Surgery

Cataract surgery is performed in a day surgery as a walk-in, walk-out procedure. You are positioned on a bed and your eye is completely numbed with anaesthetic drops. Intravenous sedation is given as a “twilight anaesthetic”. The vast majority of patients have no recollection of the surgery!

I use a variety of different cataract surgery techniques to optimise the result.  Usually, I will make two tiny, keyhole incisions: the largest is only 2.2mm wide.  The incisions are so small that they seal with a watertight closure, without the need for stitches.

The new artificial lens implant is rolled up and injected through the incision. It opens up inside the eye to rest inside your natural lens capsule. I then rotate the lens implant, so that it aligns precisely with the optics of the eye. To do this, I use an image guidance system projected inside the eyepieces of my surgical microscope.

The entire procedure takes approximately 15 minutes.

Optimal surgical technique is highly ritualised to minimise the risk of complications, and to produce highly consistent results.

I will check on you after the surgery before you go home.

STEP 7. Post-operative Eyedrops

Medicated eye drops are used for four weeks to help the eye to heal. Several brief check-ups are performed in clinic during this time. If glasses are required, these can be updated four to six weeks after cataract surgery.

What to expect immediately after cataract surgery

The morning after surgery vision mightl be Light will seem extremely bright, as your retina won’t be used to seeing the full colour spectrum so intensely. Although the brightness settles quickly, you may choose to wear sunglasses for a while.

Another after-effect is that the eye feels gritty. This is due to the strong antiseptic solutions required during the operation, and the tiny incision, which is in the outer corner of the eye. This irritation improves over a week, and post-operative eyedrops help to soothe it.

Over the next few weeks vision keeps progressively improving, but it fluctuates. This is due to dry eye, which always gets worse for a while.  I provide you with instructions on how to manage this.

What you shouldn’t do after cataract surgery

I tell my patients that they can basically do everything that they normally would, with a few important exceptions:

  • No driving for 24 hours.
  • No eye make-up for 5 days.
  • No eye rubbing for 2 weeks.
  • No swimming or strenuous exercise for 2 weeks.

What you can do after cataract surgery

  • You can read, watch television, bend over and go about normal household activities.
  • Shower and wash your face. (Close the affected eye in the shower for one week).
  • Wear makeup on your face (but no eye makeup for five days).
  • Light exercise (e.g. walking, light yoga, golf, treadmill).

The risks of cataract surgery

All medical procedures carry risk and these risks will be discussed with you as part of your informed consent.

Fortunately, with the latest technology and surgical technique, serious complications from cataract surgery are rare. However, complications can always occur no matter how much care, judgement and skill are employed.

I am fortunate to have specific training and expertise in repairing the complications of cataract surgery. Correcting patients who are dissatisfied with previous cataract surgery forms a large part of my work.

The main risks of cataract surgery are:

  • Infection.
  • Haemorrhage. Bleeding varies from mild bruising on the surface of the eye (common), to severe vision threatening haemorrhage (very rare).
  • Retinal detachment.
  • Vision worse than pre-op vision (rare) or permanent loss of sight in the operated eye (very rare).
  • Cystoid macular oedema. Retinal swelling that reduces the clarity of vision. This ranges from mild (approximately 5%, resolves quickly), to severe macular oedema (very rare).
  • Eye discomfort. This ranges from mild dry eye (very common), to strong pain requiring medications (rare).
  • Unexpected defocus post-op. Occasionally, the eye heals after surgery with a different focus to what was anticipated. If required, focus error can usually be treated with another operation.
  • Imperfect vision requiring a second operation. There are many reasons why a patient may require a second operation in order to achieve their best possible vision.

What are the symptoms of cataract?

Even though cataract is a simple problem to understand, cataracts cause a myriad of different eye symptoms. This is because cataract doesn’t just make the lens cloudy: the cataract will also change the colour of the lens, as well as the way it focuses light.

Here are some of the common symptoms of cataract.  If you experience these, you should see an eye specialist.

Reduced clarity of vision.

All forms of cataract absorb and scramble incoming light. This causes the image on the retina to be dimmed and blurred.

Patients with cataract may notice that their vision is not as sharp as it used to be, even with updated glasses. Some patients can still read the vision chart, but cataract causes a softness to the vision. Each letter will no longer be as crisp and defined.

cataract surgery blurry vision

Glare and halos when driving at night.

A cataract is like a dirty chandelier. Rather than focusing the image onto the retina, the cataract scatters the light inside the eye. This is why patients with cataract often report that the headlights of on-coming cars seem more dazzling, and they see halos and streaks around the headlights.

glare and halos driving at night cataracts

Changing prescription of glasses

The lens of the eye is living tissue, and a cataract is constantly changing. As the cataract develops, the focus of the eye also changes. This necessitates updating your glasses prescription more frequently.

Reduced vibrancy of colours.

As a cataract develops, colours become dull and slightly yellowed. You may not even notice that this is happening: altered colour perception is rarely perceived before cataract surgery.  Afterwards, however, most patients notice that colours are much more vivid.

cataract vivid colours HOTA

Blurred distance vision but improved reading vision

Sometimes, cataract may cause your reading vision to improve, while your distance vision gets worse. This occurs because as the cataract becomes more opaque, it also develops increased focusing power. This process of progressive near-sightedness caused by cataract is called “index myopia”.

Double vision even with one eye covered

Due to cataract acting like a chandelier inside the eye, you may find that one of your eyes sees “double”. The second image is a ghosted, displaced copy of the true image. Sometimes, this can appear as “fringing” on one side of the object. This second image remains even if one eye is closed, which differentiates it from double vision (diplopia), caused by a problem in the brain.

Increasing eye pressure

If your eyes are small, anatomically speaking, a cataract can interfere with the normal circulation of fluid within the eye. The cataract can physically obstruct fluid drainage, resulting in the eye pressure increasing. This is called “angle closure”.

double vision cataract

Difficulty seeing in dim lighting.

Cataract absorbs light entering the eye, particularly blue and violet colours. But blue and violet colours are most important for our night vision, because in the evening, the colour spectrum we see shifts towards blue. This phenomenon is called the Purkinje Shift.

Cataracts themselves are yellow in colour, and the yellow blocks blue light. As a result, if you have cataract, it is likely that you see poorly at night. Shadows will appear as undifferentiated darkness.  You may not be able to see bumps in the pavement, for example.  You may also need brighter lights to read comfortably.

blue sky at night

No noticeable symptoms whatsoever!

If you’ve been told that you have cataract, but haven’t noticed any of the above symptoms, then don’t worry. That is perfectly normal too.

Many patients with cataract aren’t aware that the quality of their vision has declined. This is because cataracts develop very slowly, which can make it hard for people to recognise the change.

However, when cataract surgery is performed, these patients are often the most impressed, as they are typically surprised by just how much more vibrant the colours are, how much clearer their vision is, and how they can now see fine detail that they didn’t even know that they were missing.

What are the different types of cataract?

Cataracts are classified into different subtypes according to their appearance, as well as the location of the clouding within the lens.

The three most common forms of cataracts are the following, although there are many other forms of cataract as well.

  • Nuclear sclerosis cataract
  • Cortical cataract
  • Posterior subcapsular cataract

Each form of cataract has slightly different symptoms, because of the differences in the density and location of the lens opacity. Most patients have a combination of multiple types of cataract.

nuclear sclerosis cataract

Nuclear sclerosis cataract

Nuclear sclerosis cataracts appear as a yellow discolouration of the lens. This yellowing is not visible to the naked eye, but can be seen with a special microscope.

The yellow discolouration is caused by accumulation of urochrome within the lens.  Urochrome is a yellow pigment (the same one that colours your urine).

Nuclear sclerosis cataracts are predominately caused by UV light exposure, which causes free radical damage to the lens.  As a result, the delicate proteins of the lens clump together. The lens is naturally transparent, but loses this transparency when this happens.

If you have nuclear sclerosis cataracts, you might notice blurred vision, halos around lights, dullness of colours, and that you are unable to see clearly in dim lighting.

Cortical cataract

These cataracts are spoke-like opacities (or spokes of darkness) radiating from the periphery, or edge, of the lens towards the centre of the lens. We don’t really know what causes them.

It could be that they are a result of constant, lifelong stretching of the lens that occurs every time we attempt to focus our eyesight from the distance to near. This process is called “accommodation”. It involves a muscle inside the eye, called the ciliary body, pulling on our lens. This changes the shape of the lens, to bring what we are looking at into focus.

The constant stretching and relaxation of the lens shape stresses protein fibres within the lens. This trauma causes clefts (splits) of water to form within the lens, and the degeneration of lens proteins. Eventually, spoke-like calcifications of the lens occur.

If you have cortical cataracts, you will notice blurred vision, as well as  seeing halos and streaks around lights.

Posterior subcasular cataracts

Posterior subcapsular cataracts appear like a plaque on the back surface of the lens. These cataracts develop rapidly, and can profoundly reduce vision. It is not uncommon for a patient with posterior subcapsular cataract to lose all functional vision in the affected eye within just six months.

Posterior subcapsular cataract is caused by cells inside the lens suddenly growing in a disorganized fashion. These cells migrate to the back surface of the lens, where they are known as ‘Bladder cells’ or ‘Wedl cells’. Instead of growing as translucent, thin strands, these cells grow as dense, round clumps. This gives the appearance of an opaque plaque on the back surface of the lens.

slit lamp biomicroscope

How are cataracts diagnosed?

Diagnosing cataract is relatively simple.

Cataracts are usually diagnosed by optometrists when they are checking your glasses, or by general practitioners when filling out driving license forms. The diagnosis is based upon your symptoms (outlined above), examination of your eye, and diagnostic testing.

The most common symptoms, as noted above, are blurred vision, glare when driving at night, frequent changes in your glasses prescription, and difficulty seeing clearly in the dark.

When an ophthalmologist or optometrist examines your eyes, a special kind of microscope, called a slit lamp biomicroscope, is used. The eye specialist can then assess the severity of your cataract, and where the clouding is located within the lens. Cataracts look yellow, and often have opaque specks and streaks.

In addition, several diagnostic tests can measure the severity of your cataract. These can help you and your eye surgeon decide when surgery is necessary.

Measurement of light scatter

One of these tests is the measurement of light scatter. This is done by directing lasers through the cataract, and measuring how the cataract blocks and scrambles the laser beam. The devices that perform this assessment are called “wavefront analyses”. Examples include the iTrace device, the OPD 3, the Topcon KR-1W, and the HD Analyzer.

In my opinion, the iTrace is the best device for assessing cataract. This is the device that I use in my clinic. The iTrace projects 256 laser beams through the cataract. It measures the absorption and deviation of each laser beam. The device reveals how the cataract is degrading vision, and it reconstructs a simulation of what the patient is currently seeing.

iTrace report from patient with cataract

iTrace report from one of my patients with cataract. The image on the left shows the visual potential of the eye.

The image on the right shows how the patient’s sight is being degraded by cataract.

Zeiss optical coherence tomography system, cataract

Measurement of cataract density

The density of a cataract can be measured which indicates how “opaque” a cataract is. To get this measurement, either a Pentacam, or an optical coherence tomography (OCT) device is used. I find these tend to be less reliable than wavefront analysis as cataract density doesn’t correlate well with cataract symptoms.

What to expect following cataract surgery with Dr Nick Andrew


Most people find that, if they have been diagnosed with cataracts, the surgery is comfortable and painless, and results in a tremendous improvement in vision – and in their enjoyment of life.