Cataracts

A normal lens is clear.  It lets light pass to the back of the eye and helps with focusing.  A cataract is a cloudy area in the lens inside the eye, which blocks some of the light.  As a cataract develops, it becomes more difficult for a person to see.

Cataracts are a normal part of ageing.  About half of all Australians aged between 65 and 74 have some cataract.  About 70 percent of those aged 75 and over have this condition.

Most people with cataracts have a cataract in both eyes.  However, one eye may be worse than the other because each cataract develops at a different rate.  Some people with a cataract don't even know it.  Their cataract may be small, or the changes in their vision may not bother them very much. Other people who have cataracts cannot see well enough to do the things they need or want to do. Cataracts may mean that a patient’s vision fails to meet legal driving standards.

Some Symptoms of Cataract

• Cloudy, fuzzy, foggy, or filmy vision.
• Difficulty reading
• Changes in the way you see colours.
• Problems with glare from car headlights, or the sun.
• Frequent changes in your glasses prescription (increasing short-sightedness).

These symptoms can also be signs of other eye problems.

How is a Cataract Treated?

A change in your glasses, brighter lighting, stronger bifocals, or the use of magnifying lenses may temporarily help improve your vision.  Usually though surgery is necessary to remove the lens and replace it with an artificial intra-ocular lens (IOL) implant.  This is one of the most common and most successful surgeries performed in Australia today.

Just because you have a cataract does not mean it must be removed immediately.  Cataract surgery can almost always be put off until you are unhappy with the way you see.  Your doctor  will tell you whether you are one of a small number of people who must have surgery.  For example, your doctor  may need to see or treat an eye problem that is behind the cataract.  Or surgery may be required because a cataract is so large it could cause damage to other parts of the eye or could become more difficult to remove if left for much longer.

Benefits of cataract surgery

• Everyday activities: driving, working, reading
• Moving around, safety, independence
• Social activities, hobbies
• Less dependence on glasses

What Should You Know About The Surgery?

Cataract surgery is performed in the operating theatre, but most people do not need to stay overnight in a hospital.  However, you will need a friend or family member to take you home, as you may be given sedative medication during the surgery.

Painless Cataract Surgery

Cataract surgery is a painless experience.  People usually stay awake during their surgery and can resume their normal activities almost immediately afterwards.  Two kinds of anesthesia are used to numb the eye:  Topical Anesthesia and Regional Anesthesia

Topical Anesthesia is very popular because injections around the eye are not required.  This is safer for some patients (Eg. short-sighted eyes).  Instead, drops are used to numb the eye.  The anesthetist may give a sedative injection into the back of the hand to settle any “nerves”.  No eye patches are needed, and people usually notice improved vision immediately after surgery.

Regional Anesthesia involves gently injecting numbing medications into the tissues around the eye. This mean the eye cannot see, move or blink during the operation.  Regional anesthesia gradually wears off 2 to 4 hours after the surgery.  The eye is patched for the first day and night and people begin to notice their improved vision by the next day.  There are advantages to each kind of anesthesia, so the specific needs of each surgery patient will be carefully considered by the anesthetist and surgeon in selecting the most suitable method of anesthesia  General anesthesia may rarely be used in young people.

Removing And Replacing The Lens:  No-Stitch Surgery.

Your doctor uses phacoemulsification, an advanced technique that allows the cataract to be removed through a tiny, secure opening 3 mm long.  The lens is removed by a small ultrasonic probe inserted through the incision.  Your doctor also uses intraocular lenses which can be folded to fit through the same small incision.  They then unfold within the eye. Once the lens is inside the eye it stays in position permanently.

This type of surgery means your recovery period is dramatically shortened and your eye recovers much more quickly than previously.  Normal activities such as driving, walking and sports can usually be resumed within a few days.

One of the side benefits of cataract surgery is an improvement in the focus of the eye after surgery. Often patients see much better in the distance than they ever have.  Sometimes your doctor  performs an extra incision on the cornea to decrease pre-existing astigmatism.  Reading glasses are usually needed, and are usually prescribed by the Optometrist about 3 or 4 weeks after surgery.  Some newer IOLs (see below) are able to give good vision for both distance and near vision.  Please tell your doctor  if this interests you.

Before surgery the eye is precisely measured so an individual lens implant can be chosen for you.  Your doctor  uses the latest technology to determine the implant strength needed to give you the best possible vision.

Can a Cataract Return?

A cataract cannot return because the lens has been removed.  However, in about 5% of all people who have phacoemulsification, the lens capsule later becomes cloudy.  This cloudiness of the lens capsule, if it occurs, usually develops a year or more after surgery.  It causes the same vision problems as a cataract does.  The treatment for this condition is a procedure called YAG capsulotomy.  Your doctor uses a laser to make an opening in the membrane behind the implant, immediately improving vision.  This is done painlessly in the office without an anesthetic and takes just a few minutes and does not require a hospital stay.  Most people see better after YAG capsulotomy, but, as with cataract surgery, complications can occur.  Your doctor will discuss the risks with you.  YAG capsulotomies are not performed as a preventative measure.

Is Cataract Surgery Right for Me?

Most people who have a cataract recover from surgery with no problems and improved vision.  In fact, serious complications are very rare with modern cataract surgery.  This type of surgery has a success rate of 99% in patients with otherwise healthy eyes.  But no surgery is entirely risk free.  Although serious complications are not common, when they occur they could result in loss of vision (see below).

If you have a cataract in both eyes, it is usual to wait a few weeks until your first eye heals before having surgery on the second eye.  If the eye that has a cataract is your only good eye, your doctor  will weigh very carefully the benefits and risks of cataract surgery.

You will be able to make the right decision for yourself if you know the facts.  Ask your doctor  to explain anything you do not understand.  There is no such thing as a "dumb" question when it comes to your health. You may wish to write down questions to ask your doctor  to help you make an informed decision about treatment.

Options for Focus and Intra-ocular Lens (IOL) Choice

Until recently the only intraocular lens choice for most people has been a monofocal (single focus) lens with the focus set for distance vision.  This means that reading glasses are required for near vision for that eye.  Another option is to leave the second eye with near focus when that eye has its cataract surgery.  This is called monovision, where one eye is set for distance focus and the other for near focus.  However, this means that the distance vision in the near focus eye without a spectacle lens is not as sharp as it could be.  Many people find this situation very useful and some find it intolerable.  We can usually test for this before surgery.

In recent years newer IOLs have been produced which can mimic natural vision and allow focusing at far and near, making reading glasses less necessary.

These Multifocal/Bifocal IOLs can potentially restore a full range of vision for cataract patients.  They provide the ability to simultaneously focus on faraway objects, and on objects that are near.  The result is increased spectacle independence across a range of distances.  Previously long-sighted patients have found this lens most suitable.  Short-sighted patients are generally not as happy with it.

Haloes around car headlights at night (see diagram below) are a common annoying side effect with this type of lens, but this tends to improve after a month or two.  A very small percentage of patients (less than 1% in US Clinical Studies) have been dissatisfied to the point of requesting replacement of the lens.

Vision under low light conditions may be less sensitive than with monofocal IOLs.  There is a 25% chance that near vision may not be good enough to read small print without glasses with the ReZoom IOL.

The ReStor and Tecnis lenses have a stronger near focus and are somewhat better for reading, although the text has to be held fairly close (33 to 50cm).  Haloes are less troublesome.  Intermediate (1m) focus is not as clear as with the ReZoom, and computer glasses may be needed.

If the pupil of the eye is very small (less than 2. 5 mm) such as in bright sunlight, the near vision with these lenses may not be better than with a monofocal lens, and reading glasses may be needed.

Haloes: The top image represents a night scene with a monofocal IOL, the middle one is said to represent the same scene through a diffractive IOL such as the Tecnis or ReStor, and the lower through a refractive IOL such as a ReZoom or Array.  However some patients with the ReStor and Tecnis do describe haloes as bad as the lower image.

The ReZoom IOL costs about $350 and is covered by all health insurers. The ReStor and Tecnis lenses are more expensive ($750 to $1000) and are covered by most insurers.  Discuss with your doctor  if you are interested in these lenses.

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