James P Kersey
James P Kersey

Refractive Lens Exchange

This page gives you information that will help you decide whether to have Refractive Lens Exchange surgery. You might want to discuss the contents of this page with a friend or relative. Before you undergo the procedure, you will be asked to sign consent forms confirming that you understand the nature of the procedure and specifically the risks involved. If you have any questions regarding the procedure, please do not hesitate to ask me.


Refractive lens exchange (RLE) is a procedure designed to change the spectacle correction of your eye, typically with the goal of reducing your dependence on spectacles. Some people undergo the procedure to reduce their short-sightedness, some their long-sightedness, but astigmatism can also be effectively treated. These concepts will be explored in more detail below.


RLE is an example of a refractive surgical procedure, other such procedures including laser eye surgery and implantable contact lenses, all of which change your spectacle correction (refractive error). I have recommended RLE for you, rather than other procedures, as your eyes and goals are more suited to this procedure than other refractive techniques.



Short- and long-sightedness


If an eye is longer in length (diameter), or more curved, than usual, the eye is too powerful from an optical point of view and light rays are focused in front of the retina, rather than on the retina. This is short-sightedness, or ‘myopia’, and means that people would need to wear glasses or contact lenses in order to see in the distance, although such people can typically read without glasses. The higher the degree of short-sightedness, the closer to the eye that objects need to be held to be seen clearly.


If an eye is too short, or not curved enough, the eye is optically too weak to see clearly even distant objects and the eye is categorized as being long-sighted, or ‘hypermetropic.’ In youth, the lens of the eye is able to provide additional focusing power, which allows distant objects to be seen by long-sighted people without glasses. However, as one ages, the ability of the lens to focus diminishes and there will come a point in time that reading becomes impossible without glasses, followed by difficulties in seeing even in the distance without glasses.





Presbyopia is the normal age-related decline in focusing power described above. While its onset is typically noticed by long-sighted people first, it affects us all and explains why the majority of people in their late 40s start to need reading glasses; as the focusing power diminishes, people have to hold books etc. further and further away from them. Short-sighted people have the option of taking off their glasses for reading.


Treatments for presbyopia include wearing reading glasses, the use of contact lenses in one or both eyes (typically one having a higher strength lens to allow reading, =‘monovision’), and surgical treatments.


Surgical treatments include refractive lens exchange (RLE), replacing the lens of each eye with: (i) multifocal lenses, see below; or (ii) different powered lenses in each eye, giving one eye distance vision and one eye near vision (monovision, or blended monovision, depending on the individual, see page 5). Another treatment is the placement of a corneal inlay (e.g. KAMRA) in the centre of the cornea, which utilizes the pinhole effect to enhance depth of field; Mr Kersey does not carry out this procedure himself but is happy to advise you of a suitable surgeon if this procedure appeals.




When most people think of an eye’s shape, they think of a round structure, like a football. In truth, most eyes are more rugby ball-shaped, with the eye being a little squashed in one direction. This irregularity is known as astigmatism and is easily corrected with glasses, but, if marked, a patient’s vision without glasses will be quite poor.


Astigmatism can be corrected surgically either by laser eye surgery, or by using an astigmatic correction lens as part of the RLE procedure. More information regarding this is given below.



Why RLE for me? I thought I needed laser…


When many people think of vision correction, they automatically assume this will be done with a laser and are surprised when RLE is recommended instead. Laser eye surgery is a good, safe treatment for patients who wish to simply change their distance spectacle correction, but does not effectively treat presbyopia (see above). In addition, the amount of short– and especially long-sightedness that can be safely treated is limited to a small range when using laser. Furthermore, if there is the earliest hint of cataract, then laser eye surgery can complicate subsequent required cataract procedures and lead to suboptimal results.


Although there are minor changes in the cornea with the passage of time, which can lead to minor changes in spectacle prescriptions after RLE (and laser), most changes in spectacle prescription in patients’ 50s and beyond is lens/cataract-related and RLE removes this change, resulting in a more stable prescription as you age.


RLE - The procedure


The procedure is identical in many respects to the long-established technique of small- or micro-incision keyhole cataract surgery, where the contents of the native lens of the eye are removed, before a new lens is inserted into the eye. In RLE, the lens contents are removed before becoming cloudy, effectively preventing a cataract from ever forming.


The total time in the hospital is usually less than 2½ hours, with most of this time being taken up with eye drops being administered in preparation for the procedure. I recommend a small sedative for most patients, as most people are naturally anxious regarding their eyes; this usually makes the whole procedure much more relaxed. Immediately prior to the procedure, further eye drops (local anaesthetic) are given, and the eye may be marked with a special pen if certain types of lens implant are to be used (see below).


For the procedure itself, I will generally have some music for you to listen to for the 15-20 minutes that the procedure takes. Once you are comfortable lying down, your eye will be cleaned with special antiseptic and a drape will be placed over your eye to keep the area clean. A small clip is then placed, which means that you will not have to worry about blinking at all.


During the procedure, you will not be able to see what is happening, but you will be aware of a bright light and unless directed otherwise I would like you to look straight at the light itself. You should not feel any pain, but, when using anaesthetic eye drops alone (my preferred technique), you may at various times be aware of a pressure sensation in the eye, although I will always warn you when these sensations are expected. In addition, many patients are aware of a lot of fluid running over the eye at various stages in the procedure.


Some patients may require more anaesthetic than simply eye drops alone; fortunately, it is nearly always possible to tell in advance which patients may benefit from extra anaesthetic and this is easily administered with a no-needle technique. Alternatively, for some patients, a general anaesthetic (going to sleep) may be appropriate and this is easily arranged in advance, if desired. In the unlikely event of you feeling any discomfort, you should squeeze the nurse’s hand and I will happily give you extra anaesthetic.


The RLE procedure itself involves the creation of a small incision less than 3mm in width at the junction of the white of the eye and the clear cornea at the front. Through this tiny, self-sealing hole the front surface of the lens is carefully opened and the contents of the lens are removed, typically with the help of a state-of-the-art ultrasound probe. A new lens is placed into the lens bag that is left behind and the eye is then sealed. Throughout most of the procedure, the eye is bathed in a special fluid and at the end of the procedure an antibiotic is instilled into the eye.


After the procedure, the clip and drape are removed and I will place a clear plastic shield over your eye, in order to keep the eye clean for your journey home, and overnight. You will be given an eye drop to be used four times a day, the purpose of which is to reduce normal postoperative inflammation and the remote possibility of infection. Before you leave hospital, I will confirm your telephone number with you, as I will ring you the following day. In addition, I will give you my personal telephone number, should you have any concerns.



Which lenses are used in RLE?


A wide range of lenses can be placed within the eye, although typically the measurements that are taken of your eye prior to surgery guide the placement of an intraocular lens (IOL) of the correct power in order to achieve the appropriate vision desired in your eye after surgery. Most people choose to have a lens placed in the eye that allows them clear distance vision without glasses, but, with the placement of a standard, monofocal IOL, patients would almost certainly require reading glasses for close work. With modern laser eye measuring techniques, the overwhelming majority of patients (at least 85%) achieve their ‘refractive’ goal (i.e. the desired spectacle prescription, if any, after surgery).


There are three main kinds of premium intraocular lenses (IOLs), which may be suitable for you, which will increase the chance of you not needing glasses after surgery:


  • ‘Toric’ IOLs, which allow the correction of pre-existing astigmatism.
  • ‘Multifocal’ IOLs are similar in concept to bifocal glasses or especially multifocal contact lenses, except that the lens is within the eye; the goal of these lenses is to allow the ability to see both distance (e.g. driving) and near (e.g. reading) without glasses.
  • ‘Toric multifocal’ IOLs combine the advantages of both these types of lenses.



A toric IOL is a bespoke lens placed inside an eye to correct a patient’s astigmatism, at the same time reducing the patient’s short- or long-sightedness. After surgery, the chance of needing glasses for distance is greatly reduced, although without the simultaneous placement of a multifocal component of the lens (‘toric multifocal’), patients should still expect to need reading glasses. Cataract or RLE surgery in patients with marked astigmatism using standard, non-toric IOLs does typically lead to improvements in unaided vision, but patients should not expect that their final distance or near vision will be clear without glasses. It is not always possible to use a toric lens, even if an individual has significant astigmatism; reasons include inconsistent scan data, poor corneal surfaces (e.g. very dry), irregular astigmatism and small pupils, which preclude accurate placement of the lenses.



Multifocal lenses are specially designed to create (at least) two images at the same time, one of which is in focus for near and one for distance. The individual’s brain decides which image will be ‘used’, depending on what is being looked at. With such lenses, about 85% of people achieve day-to-day spectacle independence, meaning that typically they can both drive and read, e.g. a restaurant menu, without glasses. For more prolonged reading, such as a novel, however, many patients still choose to wear reading glasses.


As multifocal lenses split the light entering the eye into at least two images, there is by definition a compromise in the quality of vision achieved. Although around 85% of patients are spectacle-independent after surgery, the distance and near vision achieved is unlikely to be as impressive as if a standard, monofocal lens (with reading glasses) had been used instead, the upside of course being the lack of a need for glasses.


Multifocal lenses are probably unsuitable for patients with optically demanding hobbies and occupations, such as astronomers or photographers, although the golfer Gary Player has notably done very well after such surgery! In the dark, some patients do complain of haloes around lights; multifocal lenses are thus unsuitable for occupational night drivers. In addition, people with relatively low degrees of short-sightedness are not ideal candidates for these lenses, as they are used to an excellent quality of unaided near vision.



Toric multifocal lenses combine the benefits of both toric and multifocal lenses, i.e. simultaneously improving astigmatism and aiming to achieve spectacle-independence for distance and near.



Other lens techniques are used in RLE are Blended vision and Mononvision


An alternative approach for people, who wish for reduced reliance on spectacles, is a technique known as ‘blended monovision’. In this technique, multifocal lenses are not used, but one eye (usually the dominant eye) undergoes cataract surgery aiming to achieve good distance vision, while the other eye is set for closer distances. While some patients (typically long term contact lens-wearing patients) can tolerate a sufficient difference between the two eyes to allow a true reading eye and a distance eye (known as ‘true monovision’), most cannot. However, aiming for a subtle difference in prescription between the two eyes (ideally around 1.25 Dioptres) allows greater functionality around the house, and is often sufficient to allow supermarket shopping without glasses and some reading, all without the disadvantages of multifocal lenses.


For blended monovision to work well, it is imperative to have a good result from first eye – typically the dominant, or distant eye – surgery. If the ‘refractive’ outcome from surgery is not as good as planned (see below, risks), then I may recommend aiming for a distance result in the second eye too. This naturally may increase the chance of you needing reading, or intermediate vision, spectacles.





The costs of toric and multifocal lenses are significantly greater than for standard intraocular lenses. The cost of most toric and multifocal lenses is included in the price of the operation. There are a small number of more expensive lenses which are not covered and a surcharge may be levied. You will be informed if this is the case.





Although your eyes will be measured using a modern, laser-scanning technique, there is no absolute guarantee that the refractive outcome (spectacle prescription, if any, following surgery) will be perfect due to: the empirical nature of the formulae used to estimate the lens power; and the variation between individual patients’ eyes in their response to surgery (e.g. lens position within the eye, and the astigmatic effect of incisions).


This means that, for distance, approximately 90% achieve a refractive outcome within 1 Dioptre of their goal, and approximately 70-75% within 0.5 Dioptre. In other words, despite using modern laser-scanning techniques for measuring eyes, there is a small, but significant chance of being spectacle-dependent following surgery, for both distance and near. The chance of patients having a significant postoperative refractive error (need for a small spectacle correction, or a “refractive surprise”) is typically greater for patients whose eyes are either very long- or short- sighted to start with. Subsequent corrective refractive surgery may be possible for some patients at a later date. This may include the placement of another ‘piggyback’ lens in the eye, in front of the new lens, or subsequent laser eye surgery on the front of the cornea of the eye.


In the extremely unlikely event of a surgical complication, it is possible that a premium lens would not be an appropriate choice of lens to implant, the decision being taken during surgery. It is important to understand that, in this eventuality, it may be necessary to use a standard intraocular lens (i.e. not a toric or multifocal lens). For some such patients, subsequent surgery to achieve spectacle-independence may be possible.


The ‘surgical’ risks encountered in standard cataract or lens surgery still apply for patients undergoing implantation of a premium lens; these include:



Some possible complications during the operation


  • Tearing of the back part of the lens capsule with disturbance of the gel inside the eye, which may sometimes result in reduced vision, and / or delayed recovery from the procedure. This occurs in less than 1:200 procedures and is less common in RLE procedures than typical cataract surgery.
  • Loss of all or part of the lens into the back of the eye requiring a further operation, which may require a general anaesthetic.
  • Bleeding inside the eye.
  • In the highly unusual event of a significant complication, it may not be safe to place a lens implant. In this case a subsequent procedure would be necessary to implant an IOL at a later stage.


Some possible complications after the operation.


  • Allergy to, or intolerance of, the eye-drops used. A change in eye drops helps.
  • Bruising of the eye or eyelids. This is uncommon.
  • High pressure inside the eye. This is more common in patients predisposed to glaucoma
  • Clouding of the cornea. This is very rare in RLE patients.
  • Incorrect strength or dislocation of the implant. This is exceptionally rare in RLE patients. In patients with multifocal lenses, centration of the lens is crucial; in the unlikely event of the lens being decentred at your postoperative visit, and your vision is suboptimal, then a small corrective procedure may be advised.
  • Swelling of the retina (macular oedema). Drops are given following surgery to reduce the risk of this happening.
  • Detached retina, which can lead to loss of sight. It is important to state that RLE does not change the underlying ‘medical’ state of the eye; initially short-sighted patients continue to have a higher underlying risk of retinal detachment than non-short-sighted patients.
  • Infection in the eye (endophthalmitis), which can lead to loss of sight or even the eye, despite prompt treatment. I go to great lengths to reduce the risk of postoperative infection to as low a level as I believe is possible, including the use of antibiotics, special eye cleansing techniques, mask wearing during the procedure and no-touch techniques. In the exceptionally unusual event of infection (less than 1: 1,000), the scientific literature suggests that the organism in question is nearly always borne by the patient, rather than being ‘cross-infected’ from the hospital / staff.


Complications are rare and in most cases can be treated effectively. In a small proportion of cases, further surgery may be needed; the risk of this happening is approximately 1 in 300.  Very rarely, some complications can result in loss of sight.  Overall the risk of severe loss of vision (blindness) in the affected eye is about 1 in 1000.


The most common complication is called 'posterior capsule opacification', affecting around 1:15 patients. It may come on gradually after months or years. When this happens, the back part of the lens capsule, which was left in the eye to support the implant, becomes cloudy. This prevents light from reaching the retina. To treat this, I use a laser beam to make a small opening in the cloudy membrane in order to restore the eyesight.  This is a painless outpatient procedure, which normally takes only a few minutes. This treatment is available on the NHS if desired and is not normally included as part of your RLE package.


Bournemouth Nuffield Team at Laser Eye Surgery training day

Cataract training simulator at Bournemouth

Through generous funding from the regional training organisation and the Friends of Bournemouth Eye Unit, we have managed to secure the purchase of a virtual reality cataract simulator. This state of the art training simulator will enhance the experience of both trainees and patients while young ophthalmologists learn to perform cataract surgery.

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