Cataract Surgery, Retina Surgery and Macular treatments - Exeter

What is a cataract?

 

 

The eye is like a camera with lenses at the front and a photographic film (retina) at the back.  There are two lenses in the camera, the cornea (clear window at the front of the eye where contact lenses are placed) which is most of the focusing power of the eye (coarse focus) and the lens inside the eye which is the fine focus system of the camera. A cataract is a cloudy lens inside the eye. The treatment for cataract is to remove the cloudy lens with an operation and replace it with a new clear lens. The timing of a cataract operation is when you the patient are sufficiently troubled to wish to proceed with surgery. If you are happy with your present quality of vision then it is unlikely that surgery would be needed at this moment in time. Cataracts do not improve however and usually slowly progress with increased blurring of vision or glare symptoms over months or years. They usually affect both eyes but often affect one eye more than the other.

How is cataract surgery performed?

 

 

Before the operation a measurement has to be taken of the eye with a machine called an IOL master. This is a very accurate, totally painless assessment of the eye with a laser based machine. It just requires you to look at some spots of light and measures the curvature of the cornea at the front of the eye and the length of the eye from front to back. Each eye is slightly different in shape but with these two measurements the machine calculates an accurate strength of focus for the new lens implant (called an intraocular lens or IOL) for your particular eye.

 Cataract surgery is performed through small incisions at the edge of the cornea (clear window at the front of the eye) and the incisions are so small that they seal by themselves and do not require any stitches. The surgery is performed as a day case procedure in hospital (you do not need to stay overnight) and the operation usually takes about 15 to 20 minutes. Most operations are performed with a local anaesthetic (to numb the eye) but if you are anxious about surgery some sedation can be given by the consultant anaesthetist to help you relax.  If you are very anxious surgery can also be performed under general anaesthesia (you are asleep) as a day case procedure.

You do not have to change your clothes before going into theatre. Drops are placed on the surface of the eye to be operated upon to both numb the eye and enlarge the pupil. You will be asked to lie on a comfortable theatre trolley which as been specially designed to accommodate all requirements for positioning and in particular for people with arthritis or breathlessness.  The skin around the eye is then cleaned with an iodine solution (provided you are not allergic to iodine) to minimise the risk of infection. The anaesthetist will then give the injection around (not into) the eye to completely numb it. This is all performed in a room next door to theatre called the anaesthetic room.

The trolley is then moved into the main theatre and positioned under the operating microscope. The skin around the eye is then cleaned once more with iodine to again keep the risk of any infection to the absolute minimum. This may sound old fashioned but iodine is still the best thing for quickly destroying any bugs (bacteria) that are on or around the eye and therefore minimises the risk of infection.  Do not be worried if you feel the light pressure of the gauze swab cleaning the skin around the eye. This is normal and does not mean the local anaesthetic has not worked. The injection will numb the eye (and therefore you will not feel the operation) but it does not numb the sense of touch for the skin around the eye.

The face is then covered with a light paper drape with a small hole that allows access to the eye having surgery.  A small “tent” is created with the drape so that it is not up against the face and fresh air is gently blown into the “tent”. A small instrument called a speculum is placed to keep the lids apart and stop you from blinking and sometimes you are aware of a gentle pressure on the lids that can feel a little strange but is not painful.

The eye having surgery is now out of your control but you can still blink with the other eye. You can keep this eye open if you wish (you will only see the colour of the inside of the drape) but most patients prefer to gently close this eye during the operation. The surgery usually takes 15 to 20 minutes and someone can hold your hand during surgery if you wish.  Some patients note that everything goes dark during the operation some note interesting coloured light sensations and some are aware of shapes moving. There are also some buzzing noises during the surgery which again is completely normal and is the special small incision cataract machine called a phacoemulsifier in action.

If you wish to cough or move during the operation you can do as I can come out of the eye with my instruments quickly and safely due to the self sealing wounds.  I would just need a brief warning prior to your moving by either putting up your hand if no one is holding it or if you have a hand holder, by giving the persons hand a squeeze.  You can then cough or sneeze safely before I return to surgery when you are once more comfortable.

When the operation is over the drape is removed (sometimes there is a bit of pulling on the skin as it is removed) and a clear plastic shield placed on the eye with sellotape. The eye is not usually padded and you can blink normally under the shield. The shield can be removed after a couple of hours and just placed back on the eye at night only for the first 2 nights. There is no need for anything to cover the eye during the day.

It usually takes about 2 to 4 hours for the local anaesthetic to ware off and during that time the vision may still be quite blurred and sometimes the eye does not move as well as the unoperated eye and this can cause double vision (seeing two images of everything).  This however is transient and you can be reassured that it will go.

The drugs that enlarge the pupil prior to cataract surgery are very powerful and the pupil can stay enlarged for up to 48 hours after cataract surgery.  This can result in some residual blurring of vision and bright lights can be a little uncomfortable so dark glasses may be needed if going outside for the first couple of days.

The vision should however improve significantly after a couple of days.

Drops need to be placed onto the surface of the eye four times a day for four to six weeks. This is performed by first washing your hands then gently pulling the lower lid down and away from the eye and placing a drop in the groove created between the inner aspect of the lower lid and the eye. If you think you have “missed” put another drop in as you cannot “overdose” on these eye drops. The drops are a combination of steroid (to keep the eye comfortable) and antibiotic (to prevent infection). 

The small incisions created at the time of surgery take about 6 weeks to heal. The shape of the eye can change during this healing process and this is why you should not go to the optometrist (optician) to have your glasses updated until the drops have finished.

What are the risks of cataract surgery?

 

 

Any operation has a risk but the risks of cataract surgery are very low. There is a one in 1,000 risk of infection or haemorrhage and a one in 10,000 risk of severe complications that result in significant loss of vision.

What can I do after cataract surgery?

 

 

Many patients feel they should considerably restrict their activity immediately following cataract surgery but this degree of caution relates to the old fashion operation where a larger wound was created requiring many stitches. With modern small incision cataract surgery there is no problem with bending over or going out for gentle exercise (such as walking) within 24 hours of surgery. It is best to avoid swimming for 4 weeks.

What would suggest something is wrong after cataract surgery?

 

 

Complications following cataract surgery are very rare but the "red flag" symptoms that require immediate review are severe pain with increasing blurring of vision, bright lights being very uncomfortable for the eye (and not just things being much brighter after cataract surgery), and increasing redness of the eye in association with the previous symptoms.  A bright red patch on the white of the eye with good vision and no pain is likely to be a simple bruise associated with the local anaesthetic injection called a subconjunctival haemorrhage and although may look alarming will gradually fade over a few weeks.  If you are in any doubt it is always best to get an urgent medical review of the situation.

Can I do away with my glasses after cataract surgery?

 

 

Patients who are long sighted or short sighted can be made normal sighted (seeing clearly in the distance without glasses) at the time of cataract surgery as the lens implant is calculated so that you do away with your glasses for distance and only need reading glasses. Sometimes a weak strength of glasses is still need to get the distance vision as good as possible for tasks such as driving at night.

What is astigmatism?

 

Patients who have astigmatism (the cornea or clear window at the front of the eye is more curved in one direction than the other like a rugby ball) can also have this treated at the time of surgery. Mild amounts of astigmatism can be improved by placing the incisions required for cataract surgery in the area of the cornea that has the greatest curvature. More severe astigmatism can be very effectively treated with toric lens implants to significantly improve distance vision without glasses.

Can I do away with my reading glasses after cataract surgery?

 

 

Options for doing away with reading glasses completely are available but to date there is no “perfect solution” resulting in excellent vision at all distance without glasses.

The two current options are “monovision” and multifocal intraocular lens implants.

 Monovision

If you have cataract in both eyes, one eye can have an implant set for good distance vision and one eye for near vision.  The distance eye is usually your “dominant eye” which is the one you would use when looking down a telescope.  The “non-dominant” eye is set for near vision.

The near vision eye can have a close focus for easy reading in bed without glasses but this means a large difference in the focus between the two eyes and some people have difficulty getting used to this difference in focus between the two eyes.  This option works best in people who have already been happy with this when using contact lenses to produce the same effect.

Blended monovision (sometimes called mini or micro monovision) is a similar process but the “non-dominant” eye is set at an intermediate distance such as when looking at a computer.  The advantage of this is that the difference between the two eyes is no so great and most people are comfortable with this option and can read without glasses in a good light.  The disadvantage is that reading small print or in poor light may still require weak reading glasses and there does remain some imbalance in focus between the two eyes.

 Multifocal intraocular lens implants

The multifocal intraocular lens implant is manufactured to produce multiple images that fall on the retina (the photographic film at the back of the eye) from different distances (far and near and sometimes an intermediate distance as well).  The brain learns to ignore the image it does not want and concentrates on the image that is clear at the distance required.  The optics of these lenses are quite complicated and not without some compromise in overall quality of vision.

Some people notice glare symptoms and haloes or starburst effects which can be troublesome when night driving.  Usually these effects reduce as the brain adapts to your new vision over several months but it can sometimes take up to 6 months to resolve.  A very small number of patients are still sufficiently troubled after 6 months to require lens removal. 

As the light entering the eye is “divided up” into different focuses there is slightly less light available at each focus compared with the normal monofocal lens where all the light entering the eye has a single focus.  This slightly reduces the quality of vision at all distances but this is not particularly noticeable in good light but can be more noticeable in poor light situations such as dawn or dust or in a poorly lit restaurant.  This is sometimes called loss of “contrast sensitivity”  This effect may be more noticable as you age or if you develop macular degeneration.

If you need very high quality vision for distance and driving at night (such as HGV drivers) then multifocal lenses should be used with caution.  If patients need very high quality vision at near (such as model makers) then it is unlikely that a multifocal implant alone will produce this level of near vision and glasses may also be needed for detailed near visual tasks.

Multifocal and extended range of vision intraocular lenses

 

The two multifocal lenses which I feel are probably the best on the market to date are the Symphony lens from Abbott Medical Optics and the AT LISA trifocal lens from Zeiss.

The AT LISA provides a better quality of near vision and the Symphony reduces glare and haloes and provides a better quality of distance vision.

All intraocular lenses are designed to be easily inserted into the eye at the time of cataract surgery with minimal risk but removal of intraocular lenses is more technically challenging and whilst most of the time can be performed successfully there is a greater risk.  It is therefore important to be comfortable with a decision to have either monovision or multifocal lenses and whilst these options are very successful for most people there are some who are not suited and as with all operations patient selection is very important.  Multifocals work best if both eyes have surgery, all astigmatism is treated and the retina is healthy.

What if I have cataract and previous laser refractive surgery such as LASIK and PRK or previous Radial Keratotomy? 

 

Does being short sighted increase the risk of cataract surgery?

 

What is Fuch's endothelial dystrophy and does this increase the risk of cataract surgery?

 

Does pseudoexfoliation syndrome increase the risk of cataract surgery?

 

Can a cataract come back after cataract surgery?

 

 

Patients often ask if the cataract will come back after surgery. This does not happen but sometimes laser treatment is needed months or years after cataract surgery. When the cataract is removed, the back surface of the cataract called the posterior capsule is left behind.  It is needed to support the intraocular lens that is inserted at the time of cataract surgery to replace the focus that is lost when the cataract is removed.  If this posterior capsule was removed there would be no support for the lens in its correct position and the lens would fall to the back of the eye.

This posterior capsule is almost always clear at the time of the cataract operation and therefore allows light to pass through it and focus on the retina or photographic film at the back of the eye. The posterior capsule can however gradually become cloudy with the passage of time (sometimes many years after the original cataract operation) and you would notice the vision once again becoming gradually more blurred. The treatment is to make a central hole in the posterior capsule with laser.  It is called a Yag laser capsulotomy after the type of laser required to create the hole.

The treatment only takes a few minutes as an outpatient procedure and is therefore a very simple thing to perform. Drops are placed onto the eye to numb the surface of the eye and to enlarge the pupil. A contact lens is then placed on the surface of the eye to allow the laser to focus. You may feel a small amount of gentle pressure on the eye from the contact lens but the posterior capsule has no nerve ending and therefore the laser treatment is completely painless.  You may be aware of a red light shining into the eye (which is the aiming beam of the laser) and the laser treatment then takes a few minutes only to complete and creates a hole in the centre of the posterior capsule.

The contact lens is then removed from the eye and you should notice an improvement in vision almost immediately with a further improved over the few hours needs for the effect of the drops that enlarge the pupil to wear off.  Sometimes you may be aware of an increase in floaters in the first few days after laser which is due to some of the “debris” from the capsule falling back into the main eye cavity but this quickly improves.

No drops are needed after laser treatment and it does not alter the glasses prescription therefore you do not need to visit your optometrist (optician) after the laser treatment. Once the laser has been performed it lasts forever and does not need to be repeated.

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