What is it?
The eye is very like a camera, and has a lens that is situated just behind the pupil. The lens is naturally transparent, allowing light to pass into the eye.
The lens, together with the cornea, brings light to a focus on the retina. The lens can also change shape to enable the eye to focus on objects at various distances.
As we age the the lens loses both its transparency and the ability to change focus. The loss of transparency is known as cataract; the loss of ability to focus on near objects is termed presbyopia.
By the age of 70 most adults have some cataract even if they have otherwise healthy eyes.
Causes of cataract
The most common cause of cataract is aging. Other less common causes include:
- Medications such as steroid tablets or eyedrops
Symptoms of cataract
Common symptoms of cataract include:
- A painless blurring of vision
- Glare, or light sensitivity
- Poor night vision
- Double vision in one eye
- Needing brighter light to read
- Fading or yellowing of colours
Many things you hear about cataracts are not true. A cataract is not:
- A growth in the eye
- A film on the surface of the eye
- Something that needs to become “ripe” before it can be removed
- A cause of irreversible blindness
How is it diagnosed?
Cataracts are relatively easy to diagnose.
How is the diagnosis made?
Cataracts are detected by looking for changes in the transparency of the lens of the eye. The easiest way to see a cataract is to observe the “red reflex” of the eye. Cataracts are seen as dark zones in the red reflex.
Who can diagnose cataract?
Most cataracts are first diagnosed by optometrists and general practitioners. Patients are then referred to an ophthalmologist, who will confirm the diagnosis and discuss the benefits of cataract surgery.
There are no medical solutions for cataract. It cannot be treated by exercises, glasses, eyedrops or laser. The only solution is replacement of the diseased lens with a new intraocular lens or “IOL”.
The only treatment for cataract is surgery.
This section deals with the more technical aspects of cataract surgery. More information on what it is like to go through the process of cataract surgery can be found in having cataract surgery
The decision to operate
Many issues must be considered before the decision to operate is made. These include:
- The visual problems experienced
- Determining that cataract is present
- An assessment of whether other eye disease is present and how this will impact on the expected outcome
- A review of the risks of surgery
Preparation for surgery
Preparing for surgery involves two important processes:
- Measurements of the eye, known as “biometry”
- Completion of all paperwork including hospital admission forms and consent documents
Measurement of the eye is a critical part of cataract surgery. The curvature of the cornea and length of the eye are determined with instruments known as a keratometer and A-scan ultrasound respectively. The data is then entered in formulae that calculate the power of the intraocular lens required for each individual patient.
Admission forms and consent documents
There are certain legal requirements that must be completed prior to surgery. These include the hospital medical questionnaire and the consent for surgery.
The surgical process
Cataract surgery involves five main steps:
- Dilating the pupil
- Anaesthetising the eye
- Removing the cataract
- Implanting the new intraocular lens
Cataracts lie behind the pupil and so it must be dilated prior to surgery.
Anaesthesia for eye surgery has changed significantly over the last decade. It is very rare for people to require general anaesthesia. Most patients now have one of two types of anaesthesia:
- Topical anaesthesia
- Sub-tenons local anaesthesia
Dr McKellar prefers to use topical anaesthesia using special eyedrops to “numb” the eye. This avoids needles and results in more rapid and comfortable recovery.
Patients who are very sensitive to light or touch around their eye may require sub-tenons anaesthesia, in which a soft canula (or tube) distributes anaesthetic around the eye through a tiny opening in the conjunctiva.
Removing the cataract
Cataract surgery involves removal of the cloudy natural lens of the eye and the placement of a new clear artificial intraocular lens inside the eye to restore vision.
The easiest way to understand cataract surgery is to compare it to the process of removing the contents of an egg from an eggshell. The diagram to the right shows the cloudy lens exiting the eye.
The analogy of shelling out an egg is helpful but now no longer entirely accurate. Most cataracts are removed by small incision surgery in which the lens is broken up inside the eye and then aspirated through a tiny opening. This process is known as “phacoemulsification”.
Phacoemulsification is an ultrasound technology in which a vibrating hollow tube breaks up the cataract.
Phacoemulsification is the most common method used to remove cataracts and is the most effective method of removing hard cataracts.
Dr McKellar uses Ozil®, an advanced form of phacoemulsification in which the ultrasound tube vibrates longitudinally and transversely. Ozil® is safer and more efficient than traditional ultrasound.
Intraocular lens implantation
Following removal of the natural lens a new “plastic” lens is inserted into the eye to restore vision. Some people refer to intraocular lenses as “implants”. The power of the intraocular lens is calculated for each patient before surgery.
See below for more information on intraocular lenses.
In general the chances of successful surgery are approximately 98%. Other eye disease and complications can limit the outcome.
Risks of cataract surgery
Modern cataract surgery is very safe with approximately 98% of all patients having successful outcomes and no complications. Nevertheless no surgical procedure is risk free. The most serious risks of surgery include:
- Retinal swelling
- Retinal detachment
Most complications can be successfully treated but in rare cases vision loss and even blindness can occur. In very rare cases inflammation can damage the unoperated eye.
Dr McKellar gives all of his patients a brochure produced by The Royal Australian and New Zealand College of Ophthalmologists which further outlines the process, benefits and risks of surgery. Even this brochure does not contain all the information you may need before deciding to have cataract surgery. Please ask Dr McKellar if you have any other questions.
Having Cataract Surgery
The following instructions are intended to guide patients through the process of cataract surgery under Dr McKellar’s care at Christchurch Eye Surgery.
For more detail on the technical aspects of cataract surgery please see Cataract-Surgical Treatment.
Prior to surgery
You will have received several documents including a prescription for eye drops.
Before your pre-admission visit please:
- Complete the Christchurch Eye Surgery admission form
- Read the brochure entitled “Cataract Surgery” produced by The Royal Australian and New Zealand College of Ophthalmologists
- Note down any questions you want to ask Dr McKellar
- Start using the Voltaren Ophtha drops three days before your surgery
You will see Dr McKellar prior to your operation for a pre-admission assessment, usually on the morning of surgery. At this visit:
- Your eye will be measured
- Dr McKellar will finalise his surgical planning including advising on the best type of intraocular lens for your eye. You can find out more about this in the section on intraocular lens implantation
- There will be a time to ask and have answered any questions.
- Legal documents including the “Consent to Operate” are completed.
- Your appointment times will be confirmed.
On the day of surgery
The following instructions are specific to Dr McKellar’s patients and afternoon surgery. Please DISREGARD any other information you have read or been told by any other person.
- Wear comfortable clothing; an open neck top is preferable but not essential. You will NOT need to change out of your clothes.
- You may EAT NORMALLY. You do NOT need to fast and can DISREGARD the instructions in the Christchurch Eye Surgery form which are intended for patients having surgery under general anaesthesia.
- Continue with all your usual medicines EXCEPT pilocarpine eye drops. You DO NOT need to stop aspirin or warfarin.
At Christchurch Eye Surgery
Please arrive at Christchurch Eye Surgery no later than the time you have been given. Expect to be at Christchurch Eye for 2-2½ hours. During this time:
- A nurse will put drops in your eye to dilate the pupil.
- You will be placed on an “eye bed”.
- Dr McKellar’s anaesthetist, Dr Sharon King, will place a needle in the back of your hand (as a safety precaution) and will anaesthetise your eye.
- You will proceed to the eye theatre.
- Dr King will monitor your blood pressure, heart rhythm, and breathing during your operation.
- Dr McKellar will clean around your eye, cover the eye with a sterile drape and perform the surgery required.
- During surgery you will be aware of light from the operating microscope, Dr McKellar’s hands touching around your eye, and machine noises. You may feel mild pressure in your eye but not pain. For more detailed information on the technical aspects of eye surgery see Cataract-Surgical Treatment.
- At the end of surgery you will be transferred to recovery for light refreshments before leaving for home.
After eye surgery
There are just a few simple dos and don’ts following surgery:
- Let Dr McKellar know if you have any concerns.
- Be careful not to rub or poke your eye. Take care around small children, pets and in the garden.
You can shower and wash your hair at any time but don’t plunge your head underneath the water in the bath, swimming pool or spa for two weeks.
- You may bend down and resume normal physical activities.
- Take care when walking on uneven ground or down stairs, and when crossing the road. You will need time to adjust to your new vision. For this reason we recommend that you don’t drive the day following surgery.
Following routine cataract surgery your eye will be checked on two occasions, the morning after surgery and again a month later. Patients with other eye diseases may need additional visits.
What is normal?
Following cataract surgery:
- There may be some mild discomfort.
- It may take several days for the focus of your eye to settle and there may be some fluctuation in your vision.
- Your eye will be more sensitive to light after surgery, so you may want to wear sunglasses for your own comfort during this time.
- Any redness and bruising should be gone after two weeks.
- Pain, redness and decreasing vision are NOT normal
What is NOT normal?
Please let Dr McKellar know if any of the following occur:
- Progressively worsening pain
- Decreased vision
- An increase in redness of the white of the eye
Eye drops are a very important part of cataract surgery. They reduce the chances of infection, pain and swelling. You will normally have three types of eyedrops. Please let Dr McKellar know if you have ever had an allergic reaction to any of the medication in the eyedrops below.
If you were on glaucoma drops before surgery, continue these as usual.
|Voltaren Ophtha||4 times a day||3 days before surgery||1 month after surgery|
|Chloramphenicol||4 times a day||The day after surgery||1 week after surgery|
|Maxidex||4 times a day||The day after surgery||1 month after surgery|
Some people will have an immediate improvement in their vision after surgery, but for most patients it takes 3-4 weeks for things to settle down.
It will take several weeks for the focus of your eye to settle. If all is well at the one month review you will be cleared to see your optometrist for new glasses. You will not do any damage to your eye if you wear your old glasses until this review.
If you have any pain, blurring or redness THAT INCREASES over a day, at any stage after your surgery, contact Dr McKellar immediately. The rooms’ telephone number is (03) 343-6033. Outside of working hours call (03) 348-4155 or 021 -724-222.
If at any stage you cannot contact Dr McKellar urgently, ring Christchurch Public Hospital on (03) 364 0640 and ask for “The eye registrar on call”.
Cataract Surgery after Laser Surgery
Cataract surgery in patients who have had previous laser vision correction (LASIK and PRK) is more complex than in patients who have not had prior laser surgery.
When short or longsightedness is treated with laser, the cornea is reshaped and thinned. These changes make it more difficult to measure the eye later in life. This compromises the ability to accurately calculate the power of the intraocular lens (IOL) required at the time of cataract surgery.
Eye specialists around the world recognise this problem and it is hoped that in the near future there will be a solution. In the meantime surgeons use a variety of methods to calculate the IOL required. In general most patients will still be delighted with the improvement in their vision. Some will be more reliant on glasses or contact lenses and others will decide to have further laser surgery to fine tune the focus of their eyes. In rare cases the implanted IOL is exchanged for one of a different power.
See also The right IOL
Following removal of the natural lens a new “plastic” lens is inserted into the eye to restore vision. Some people refer to intraocular lenses as “implants”. Ophthalmologists call them ‘IOLs’ for short.
The right intraocular lens for your eye
Prior to surgery Dr McKellar will determine what intraocular lens should be implanted. This decision is based on both measurements of the patient’s eye and what the patient wants to achieve.
Monofocal lenses are implanted in patients who want to see well at one distance (far or near) without glasses and are happy to wear glasses to see well at other distances.
Toric intraocular lenses are used to treat significant astigmatism.
Multifocal intraocular lenses are implanted in patients who desire good vision at both distance and near WITHOUT glasses.
Acrysof® intraocular lenses
Dr McKellar uses primarily Zeiss® and Alcon® intraocular lenses.
Depending on a patient’s eye and the desired outcome one of three types of lens will be implanted:
- Monofocal lens
- Toric lens
- Multifocal lens (bifocal intraocular lens)
This is a monofocal, or single focus lens, used to correct the vision of patients with minimal astigmatism.
When a monofocal lens is implanted most patients will be able to drive without glasses. Spectacles will be required for near vision.
Monofocal lenses are the least expensive IOLs.
Patients with significant astigmatism benefit from the implantation of a toric lens.
When a toric IOL is implanted most patients will be able to drive without glasses. Spectacles will be required for near vision.
Toric lenses are more expensive than a single focus lens.
Patients usually require reading glasses after successful cataract surgery.
Multifocal lenses are bifocal IOLs that provide good vision at both distance and near. This is achieved by circular zones on the front of the lens which bring light to two separate focal points. A toric version is available for patients with moderate astigmatism.
Most patients who have a multifocal lens no longer require distance or reading glasses after surgery.
Multifocal lenses are not suitable for all patients and are more expensive than a monofocal lens.
Custom made intraocular lenses
Some patients with marked short or longsightedness and those with significant astigmatism require bespoke intraocular lenses. Dr McKellar has used German manufactured HumanOptics® lenses for many years in patients with up to 15 diopters of astigmatism.
It is possible to plan to have one eye focused for distance and the other for near. This is known as “monovision” and is the best option for some patients.
See also The right IOL
FAQs and Links
Is cataract surgery painful?
No. All cataract surgery is performed after the eye is anaesthetised.
What if I blink or move my eyes?
Your eyelids are held gently apart with a device called a speculum. You can still blink; the speculum stops the eyelids from closing. Dr McKellar controls eye movements during surgery.
How much does cataract surgery cost?
Because there are so many different options it is not possible to give an exact figure until you have been assessed for surgery.
Some options such as toric and multifocal intraocular lenses are more expensive but result in significantly better outcomes for many patients. They also reduce or potentially eliminate the need for spectacles, a significant future cost saving.
What is the success rate of cataract surgery?
Approximately 98% of patients having cataract surgery will have their vision sucessfully restored. Other eye disease and complications can limit the outcome. Dr McKellar will inform you if the success rate in your eye is likely to be lower than in routine surgery.
Can cataracts re-grow?
No. Cataracts are not growths. Cataract surgery removes a diseased part of the eye and replaces it with a new artificial lens.
What is secondary cataract?
This is a term used to refer to the clouding of the capsule of the eye after cataract surgery. The correct term is “posterior capsule opacification”. It is treated with the YAG laser.
What is posterior capsule opacification?
Posterior opacification (PCO) is a condition in which the capsule of the lens becomes cloudy following cataract surgery. PCO is treated with the YAG laser.