Mr Nick A Jacobs FRCS FRCOphth
 
 
Clear Lens Extraction Procedure

A cataract extraction procedure is essentially a lens replacement. In the case of a cataract, there is a clouding of the lens requiring something to be done to improve vision.

In your case the identical operation is carried out in a procedure variously known as CLE (Clear Lens Extraction|), RLE (Refractive Lens Exchange) or PRELEX (Presbyopic Lens Exchange). These procedures are carried out when the lens is essentially normal and clear to allow the use of a multifocal lens implant for simultaneous distance and near vision so drastically reducing dependence on spectacle wear. The ideal patient will be 50 years plus and already require a distance spectacle correction. Such a patient who has multifocal lens implants in both eyes will usually have good distance vision as well as intermediate and close vision.

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These lenses are permanently focused both for distance and for near and make you more spectacle independent. These are not the same as bifocal glasses, you do not have to adjust your head position to see distance and near. No guarantee is ever given that you will never need to wear glasses at all. Some patients with these lenses do note symptoms of halos around lights for some time following surgery up to 4 months. A few patients, who have a degree of astigmatism or who are not perfectly corrected for distance, may even opt for a further laser corneal procedure to get a perfect result eventually. This is normal in some cases and does not indicate that there was something wrong with the original surgery.


Every patient has to have special measurements taken of the eye to calculate the power of the lens implant that will be used to replace the cataract. This measurement is called biometry and it is a combination of measurement of corneal curvature and measurement of the length of the eyeball.

Contact lenses can cause distortion of the cornea so any patient wearing contact lenses must not have worn them for three weeks before these measurements are taken. In this period you must not wear them even for short periods, as this will spoil the result of your operation.


The operation is usually done under local anaesthesia but may be done under general anaesthesia or with some background sedation. Patients have dilating drops about an hour before the procedure. Local anaesthesia involves an injection of anaesthetic next to the eyeball and this is generally well tolerated, but can be associated with some discomfort. The operation may be done as a day case or an in-patient procedure. Day case patients go home the same day. The procedure itself involves removing the lens and usually replacing it with a multifocal acrylic lens implant. The technique is called phacoemulsification. In this technique a small incision up to 3mm wide is made into the eye which is self-sealing. This incision is made at the edge of the cornea where the coloured iris changes to the white of the eye. The lens in the eye has an envelope known as the capsule around it. A large circular tear is made in the front of this envelope.

Then the phacoemulsification technique uses an ultrasound tip to break up the lens matter through the small incision. Once this is done the multifocal lens implant is injected through the incision into the envelope space left by removing the cataract. As the incision is self-sealing it should not require a stitch. A microscope is used for this operation as it is delicate and precise.

Whilst you are having the surgery, a bright light is shone into the operated eye and the other eye is covered by some paper. Therefore, you do not see any details of the surgery itself.

Some patients may require their forehead taping to help keep still during the operation.

Video of operation


Immediately after the operation your vision should be improved and colours appear brighter. There should be no pain, only a little discomfort. The eye may be rather red for a few days, and bright light can be uncomfortable. It is usual to go home very soon after surgery. There will be drops to use about four times a day for up to a month. Do not use the drops for longer than recommended as wound healing will be delayed. A protective shield should be taped over the eye at night time for a couple of weeks. The eye must not be rubbed at all.

The first follow-up attendance is a week or two after surgery. If the eye becomes painful, increasingly blurred and more sticky before this visit, an urgent examination is necessary. A check will then make sure there is no infection in the eye.

As mentioned, the plastic lens implant is placed into the original lens envelope. This layer can itself become cloudy and thickened in some patients. The timing of this varies from weeks to years. If it does happen, vision will gradually become blurred again. The surgeon can treat this easily by a procedure using a special laser known by the initials YAG. A small hole is cut in the thickened capsule in the middle of the pupil, then a clear path is made for the light to enter the eye. After this treatment a short course of eye drops is given. There is a common misunderstanding that this form of laser treatment can replace the whole cataract operation. This is not true.


As with any operative procedure there may be complications in a very small number of cases. The most common problems are:

During the operation:

  • During the operation, damage to the eyeball during the local anaesthetic injection
  • Damage to lens capsule with or without loss of gel
  • Loss of clear lens into the back of the eye requiring a further operation
  • Insertion of lens implant in front of pupil rather than behind it
  • Insertion of monofocal lens rather than multifocal lens implant
  • Failure to insert the lens implant possibly requiring a further operation
  • Displaced lens implant possibly requiring a further operation
  • The need for stitches
  • Retinal haemorrhage

After the operation:

  • Bruising from the local anaesthetic injection
  • Infection inside the eye needing urgent attention and antibiotics (in some cases this can lead to loss of vision)
  • A different spectacle correction from that expected, possibly requiring a further operation for various reasons
  • Allergy to medication used
  • Haziness of the cornea, usually temporary. If prolonged a cornea graft operation may be required
  • Raised pressure inside the eye, usually temporary. If prolonged may result in long term treatment, further surgery or damage to the optic nerve
  • Retinal swelling "macula oedema" affecting vision and requiring prolonged treatment
  • Ptosis or drooping of the eyelid usually resolving within weeks

Up to 2% of patients have some form of setback during or after the cataract operation which is usually reversible.

Around 1 in 500 patients may have a more severe complication relating to cataract surgery resulting in permanent loss of vision.

Most patients who have poor vision after cataract surgery already had a pre-existing eye condition apart from the cataract itself.


 
Cataract, Clear Lens Extraction, Glaucoma