A cataract is the normally clear lens inside the eye which gradually over months or years becomes cloudy causing blurred vision, glare, or double vision.
There are many different types of cataract and whilst the most common variety is associated with increasing age, other types of cataract can arise in younger age groups. Sometimes there is a more rapid reduction in vision.
Cataract surgery involves making a small 2.5 mm cut into the eye using a very fine blade. The cataract is broken down using ultrasound energy with a tiny probe inside the eye. This operation is called phacoemulsification.
Lasers have been used in cataract surgery to carry out parts of the procedure but they are used less frequently now for this purpose because there is little benefit and it makes the procedure longer and more complicated. Lasers have a better role in other eye procedures.
After the cataract has been removed a tiny artificial lens made of acrylic is injected into the eye through the incision. The lens unfolds once inside the eye. There are a variety of lens implant options and I will discuss this with you at the initial consultation.
Most cataract surgery does not require stitches because the incision is small and designed to be self sealing.
At the end of the operation a clear plastic shield is taped over the eye to protect it. This is removed the next morning.
Lens implant options in cataract surgery
Cataract surgery is an excellent opportunity to change the spectacle prescription of the eye by choosing an appropriate lens implant type.
The simplest technique is to correct the distance vision as much as possible so that after the procedure the patient may only need to wear reading glasses for near work. Most patients prefer this. However there are other options.
Toric lens implants These are used to correct astigmatism. If the clear covering of the eye, the cornea is curved by different amounts in different directions the eye is said to have astigmatism. For example if we imagine the corneal surface to be shaped more like a rugby ball than a football then there will be astigmatism. In this situation a special toric lens implant will be needed to sharpen the vision as much as possible.
Multifocal lens implants Some patients ask to have the ability to see near and distance at the same time so as to be less dependent on reading glasses.
Multifocal lens implants facilitate this by providing a distance focal point and a near focal point at the same time on the retina, the light sensitive part of the eye.
Whilst this type of lens reduces dependence on spectacles it doesn’t suit everyone. There is a compromise to the quality of vision provided. With mulitfocal lens implants some patients experience haloes around lights such as oncoming headlights or a faint ghosting of images in which a blurred outline is seen adjacent to the image. The type of vision can take up to 4 months to get used to as the brain learns to adapt to it.
EDOF or extended depth of focus lenses These are the latest types of lens that provide some near and distance vision at the same time and minimise the haloes and ghosting seen with the conventional multifocal lenses. The EDOF lenses have slightly less good near vision but are a good compromise for patients wanting to reduce dependence on spectacles.
Monovision Another way to reduce dependence on reading glasses is to have one eye set in the distance and the other set for near work. The benefit of this is that unlike with the multifocal lenses, when monovision is used there are will be no haloes or ghosting caused by the lens implant.
Alot of people are very satisfied with the monovision scenario.
During the initial consultation the best lens type for you as an individual will be discussed and decided with you. This is based on your individual requirements, your work, your hobbies and past times, your need to drive and your current spectacles. The cataract procedure will be tailored to your specific needs.
Anaesthetic options in cataract surgery
More than 90 percent of cataract operations are carried out under local or topical anaesthetic.
With topical anaesthesia eye drops are used to numb the surface of the eye. There is no pain and the patient is awake during the procedure. The patient does not see what is happens. A drape covers the other eye and face.
Sometimes it is preferable to give a local anaesthetic in which a cannula is used to deposit a small volume of anaesthetic around the eye. Needles are not used and this type of anaesthetic helps the eye to stop moving as well as removing any pain. It wears off after a few hours.
For particularly anxious patients both of the methods above local and topical anaesthesia can be combined with light sedation. In this method the anaesthetist inserts a cannula into a vein in the arm or back of the hand and injects a sedative into the vein. In this way the patient is awake but more relaxed during the procedure. The sedation wears off quickly – minutes after the procedure.
If patients are likely to move during the cataract procedure or the eye is more difficult to operate on then sometimes it is preferable for the patient to be asleep in which case a general anaesthetic is used. This ensures that the patient will be asleep and will not move. Younger patients sometimes prefer this. The patient has to fast for 6 hours before the procedure for this type of anaesthetic to be administered.
During the initial consultation I will discuss with you the type of anaesthetic to use taking into account your preferences and advice given by myself.
After surgery - post operative care
After the operation a white cotton bandage or eye pad is placed on the closed eye and then a clear plastic shield is taped on top, to protect the eye. These stay in place until the next morning, when they are gently removed.
The eyelids are opened and the eye drops can be commenced. There are two bottles to use, both four times a day. One of these is an antibiotic, Chloramphenicol to stop the eye developing infection. It is kept in the fridge between doses. The other is a mild steroid, Maxidex which dampens any inflammation. The eye drops should be used for 4 weeks.
Your eye may be a little gritty and a little red but this gradually settles. The shield stays off during the day time but I ask you to tape it on again at night time for the first week to stop you rubbing your eye in your sleep. It can be discarded after the first week.
I will arrange an appointment for a post operative check at 2 to 4 weeks after the operation.