Refractive Lens Exchange


What is Refractive Lens Exchange (RLE)?

Refractive Lens Exchange (RLE) is identical to modern cataract surgery. Both operations involve replacing the natural lens with an intraocular lens (IOL). The only difference is that cataract surgery is performed mainly to correct blur or light scatter caused by a misty natural lens; whereas RLE is performed to reduce the need for glasses or contact lenses.

There are three main IOL types

  1. Monofocal IOLs – monofocal IOLs aim to reduce spectacle dependence for distance (driving) vision.

  2. Extended Depth of focus lens implants

  3. Multifocal IOLs – multifocal IOLs aim to reduce spectacle dependence for a wider range of activities, including intermediate (computer screens) and near (reading) vision If you are suitable for RLE, Mr. David will discuss which IOL type is the best option for you.

Please scroll below for further information on lens implants

What are the benefits?

About four out of five patients are completely free of glasses after RLE with widely used contemporary multifocal IOLs.

If you do need help from glasses after surgery, it is usually for a specific activity in the near, intermediate or distance range. Approximately 95% of patients are satisfied with the outcome of surgery, and many describe it as life changing. It is designed to make you less dependent on glasses and contact lenses, helping you to lead an active lifestyle more easily.

RLE eliminates the need for cataract surgery in later life, and it is often preferred to laser vision correction for patients in the over 45 - 50 age group. In the absence of a new health problem in the eye, vision normally remains good, and your spectacle prescription normally remains stable after RLE. 

Who is suitable for RLE?

Almost any level of myopia (short sight) or hyperopia (long sight) can be corrected by RLE, and IOLs with built in astigmatism correction are available. Lens implantation techniques can be combined with laser eye surgery in suitable patients to extend the range of astigmatism treatment or fine-tune the focus outcome.

You may not be suitable for multifocal IOL implantation if you have pre-existing problems with your eye health.

What are the alternatives?

RLE is one of three main categories of operations to correct vision. The other two are laser vision correction and phakic intraocular lens (PIOL) implantation.

  • Laser vision correction does not require a lens implant, and works by altering the curvature and focusing power of the front surface of the eye.

  • PIOLs are lens implants that sit in front of the natural lens rather than replacing it.

Laser eye surgery or PIOL implantation are generally better options than RLE for younger patients who still have a clear, flexible natural lens This includes most patients under 50 years old. Laser vision correction is certainly an option for many patients over 50 years of age with a lower prescription; but the balance shifts as you get older and both flexibility and clarity of the natural lens diminish. Many people who undergo laser vision correction surgery go on to develop age related lens changes- early cataract and eventually visually significant cataract that will require cataract surgery. These lens changes may alter or change your spectacle prescription that will mean that you need spectacles.

RLE is the default option for vision correction surgery in the over 65 age group, but laser vision correction may still be a better alternative for patients with no signs of cataract and good eye surface health. Mr. David will advise on your best treatment options after reviewing your test measurements and your eye health.

The other obvious option is continuing in glasses or contact lenses.

Glasses are risk free but may limit the range of activities you can do confidently and comfortably – particularly sport and exercise. Although there are many successful lifelong contact lens wearers, comfort and tolerance tends to diminish with age. Varifocal glasses are often the main alternative to RLE for older patients. Varifocal glasses have their own optical side effects. For example, having the lower part of the varifocal lens focused for reading can make it difficult to walk downstairs confidently. Multifocal IOLs provide the range of focus in a different way, and trouble adapting to varifocal glasses does not mean that you will also have trouble adapting to multifocal IOLs. Contact lenses provide good all-round vision. They do not mist over during sport and will help you to be more active; but they can be inconvenient when travelling, make water sports more difficult, and should not be worn whilst showering or during sleep. Contact lens wear is sometimes associated with eye surface discomfort, and may be complicated by sight threatening infection.

Risks, side effects and benefits of RLE should be balanced against those for continued contact lens wear and varifocal glasses since these are the main alternatives for people considering sight correction surgery.

How is RLE performed?

RLE is performed using drop anaesthetic supplemented by an injection in the back of your hand to relax you if required. Anaesthetic may also be washed around the back of the eye to prevent excessive eye movement. A spring clip holding the eyelids apart allows you to blink safely during surgery. Your surgeon will be looking through a microscope to perform the surgery. You will be lying down under a surgical tent with fresh air coming in underneath. A sticky plastic drape covers the skin around your eye and sticks the eyelashes out of the way. Some centres offer surgery for both eyes on the same day. More commonly, second eye surgery is delayed for a day or longer to ensure that the recovery in your first eye is progressing well. The focus outcome in your first eye can also be used to help guide IOL selection for your second eye. The surgery typically takes about 20 minutes per eye. You can return home on the same day as surgery Strong pupil dilating drugs are given as drops or as a pellet placed under the lower eyelid to prepare your eye for surgery. Essential steps in surgery are: • Entry points – formation of small self-sealing entry points in the front of the eye at the junction of the white of the eye and the cornea • Capsulotomy – removal of a circular disc from the front of the membrane covering the natural lens called the lens capsule (think of the skin of a grape and you will have the right mental image of the thin, clear covering of the natural lens)

• Phacoemulsification – liquefaction and removal of the natural lens from within the lens capsule using a high frequency vibrating probe, fluid washing, and vacuum • IOL insertion – injection of the IOL and unfolding into the natural position within the lens capsule using a supporting gel to fill the front of the eye • Wash out and refilling – wash-out of the supporting gel and refilling with fluid and antibiotics


What are the different types of lens implants?

There are different types of lens implants. 
The intraocular lens (IOL) is the implant used to replace the cataract at the conclusion of surgery. The standard IOL used for cataract surgery done on the NHS is a monofocal lens. A monofocal lens is usually implanted in order to give a person good vision in the distance while intermediate and near work such as looking at a computer screen, looking at a mobile phone screen and reading will require glasses.  You may require spectacles for constant use to sharpen your vision and more so if you have a pre-existing condition such as astigmatism.

Premium lens implants, which Mr. David implants in private patients, include the following

1. Toric lens implants, which is intended to correct astigmatism.

Astigmatism is caused by an irregular shape of the cornea that gives you some degree of blurred vision at all distances. Toric intraocular lenses give you focused vision at a single distance and also correct your astigmatism so you may not need distance glasses after surgery.

As with standard monofocal lenses, however, you will still need reading glasses to see objects clearly up close. If your degree of astigmatism is too great for a toric IOL to address in full, your doctor may recommend that you have an additional procedure

If you have astigmatism in addition to cataracts, cataract operation with a toric IOL can often address it, making your vision even clearer after surgery than it was before you developed cataracts. This can also reduce your dependence on glasses or contacts after surgery.

For patients with astigmatism who would like to correct the refractive defect in distance and near vision at the same time, the ideal solution is the toric multifocal intraocular lenses. 

2. Extended depth of focus lenses (EDOF lens) which are intended to provide excellent distance and intermediate vision.
EDOF lenses employ a new technology which has recently emerged in the world of lenses. These lenses allow the wearer to increase their range of focus compared to standard Monofocal lenses.
EDOF lenses enable clear vision from far distances to intermediate distances (around an arm’s length). The patient might, however, need to wear reading glasses for close work.

3. Multifocal (trifocal) and Multifocal toric lenses which are intended to eliminate the need for glasses altogether. Multi-focal intra-ocular lenses have special features that give you good near, intermediate and distance vision-all in one lens. 
Multifocal intraocular lenses give you a good chance of living glasses-free for the majority of your activities after cataract surgery.


Who are Multifocal Intraocular Lenses for?
With standard monofocal lenses it is possible to achieve good visual acuity for distance after cataract surgery, but near vision becomes blurry.  For this reason, reading glasses are needed with this type of surgery, and many patients are not satisfied.
Multifocal lenses are designed for anyone who would like to enjoy good vision at all distances, ranging from distant to near.  With this solution patients can enjoy good vision without spectacles for all types of tasks, including driving, sports, watching television, using the computer, sewing and reading.

What are the pros and cons of multifocal lenses?
For many patients, the new quality of life without spectacles is better and more important than the minor optical disadvantages which arise after surgery. Certain activities which have not required the use of spectacles for a long time such as reading, sewing or using a computer can continue to be performed after surgery with a multifocal intraocular lens.  People who are more demanding in this aspect are good candidates for multifocal lens implants.  In any case, it is important to be aware that the use of spectacles may be required for more infrequent, specific tasks.
In some cases, depending on the lens implanted and the post-surgical result, it is true that there may be minor side effects such as glare, halo effect or increase in aberrations.  Over time the neurological system usually adapts to this new situation and the patient will become accustomed, however on occasion these may be persistent.  Adaptation varies according to person and can take a few months.  To ensure total adaptation, if possible both eyes must have been operated on under the same conditions ideally with the same type of multifocal lens implant. 


Mr. David will examine your eyes and will discuss with you the different types of premium lens implants and offer you the one that suits you best. 
If you have already had cataract surgery with a monofocal lens implant, it is possible to implant a supplementary lens in front of the existing lens implant to provide the visual and optical advantages that a multifocal lens can offer.

What are the risks?

In all forms of eye surgery, problems can occur during the operation or afterwards in the healing period. Problems can result in permanent, serious loss of vision (vision worse than the driving standard in the affected eye that cannot be corrected with glasses or contact lenses).

More commonly, problems can be corrected with changes in medication or additional surgery. Typically, these additional operations feel like the original surgery and have a similar recovery period.

Loss of vision Permanent, serious loss of vision is significantly more common after RLE than after laser vision correction or PIOL implantation, affecting approximately 1 in 500 patients. This may mean vision worse than the driving standard or, in some cases, complete loss of vision in the affected eye. Permanent serious visual loss is typically caused by damage to the retina. This can result from infection or an inflammatory response after surgery, retinal detachment after surgery, or bleeding during surgery.

Some problems occurring during surgery increase the risk of sight threatening problems afterwards. These include a common complication of surgery called posterior capsular rupture, (breakage of the membrane just behind the IOL). The UK benchmark rate for capsule rupture for all cataract surgeons is just under 1.5%. Experienced surgeons have a lower rate, but all surgeons have at least some cases affected by posterior capsular rupture. It is not always possible to implant a multifocal IOL safely if posterior capsular rupture has occurred, and this may mean greater than anticipated reliance on glasses after surgery.

Additional surgery Second operations may be required to correct a complication from the initial surgery. This could include lens repositioning or exchange, surgery to retrieve lens fragments from the back of the eye, or retinal detachment repair. With or without RLE, retinal detachments are more common if you are very shortsighted; but the risk of retinal detachment is approximately five times higher in the first four years after cataract surgery or refractive lens exchange.

Statistical techniques (biometry formulae) and eye measurements (biometry) are used to guide selection of the IOL required to correct your vision. Limitations on the accuracy of these techniques mean that laser vision correction to fine tune the focus is sometimes required to touch up the visual result after RLE.

The commonest reason for visual deterioration after RLE is posterior capsule opacification (PCO). This is a gradual misting over of the membrane just behind the IOL, which affects many patients. PCO may occur months or years after surgery, and is normally treated successfully with a one-off minor laser procedure called YAG laser capsulotomy.

What are the side effects?

Side effects are problems which most patients experience to some degree after surgery. They normally improve with time, but do not always resolve completely.

Vision Most patients experience some light scatter side effects and unwanted images in the early months after RLE. Visual side effects vary with type of IOL implanted, and are often more noticeable in some lighting conditions than others. Patients are commonly aware of a shadow or shimmering arc of light in their peripheral vision after monofocal or multifocal IOL implantation. Some types of multifocal IOLs tend to cause halos around lights. Blur or ghost images are more common with others; but almost any form of light scatter side effect can occur. It is generally accepted that all forms of multifocal IOL are associated with more optical side effects than monofocal IOLs. However, multifocal IOLs all produce a greater range of glasses freedom. Optical side effects may initially interfere with work or leisure activities, and night driving in particular. But they tend to diminish with time. 19 out of 20 patients are satisfied or very satisfied with their vision three to six-months after multifocal IOL implantation, and laser procedures to treat residual defocus or posterior capsular opacification (YAG capsulotomy for PCO) are often helpful in accelerating adaptation in the remainder.

Eye comfort Some eye surface discomfort is common in the early months after most forms of eye surgery. This is usually mild after RLE, and highly variable – often affecting one eye more than the other. Treatment and prevention are based on making sure your eye surface is healthy before and after surgery. Lubricant eye drops can be helpful, and can be taken safely in addition to your other medication when required. For patients with a normal eye surface prior to surgery, lasting problems are unusual. Eye Appearance Red blotches are often visible on the white of the eye after any form of eye surgery. These are called subconjunctival haemorrhages, and are caused by a small leak of blood under the mucous membrane covering the white part of eye wall. Although they can be quite unsightly, red blotches are temporary, and do not affect eye health; but they can take up to six weeks to go away completely.

Most IOLs are not visible. But people may occasionally notice a glint in your eye caused by a reflection from the front of the IOL within the pupil.

Will RLE affect my future eye health care?

If you develop a new eye health problem in later life, RLE implantation should not prevent you having successful treatment.

Common eye health problems like glaucoma, diabetic retinopathy, and age related macular degeneration can be monitored and treated as normal after RLE. Many patients with hyperopia (long sight) have a relatively small space for fluid circulation through the front of the eye. The space narrows as the natural lens expands with age, leaving these patients vulnerable to a form of glaucoma caused by blockage of fluid flow that can lead to sudden, painful loss of sight (‘angle closure glaucoma’).

In patients with this predisposition to later problems called ‘a shallow anterior chamber’, RLE can both reduce the need for glasses and remove any risk of future problems due to angle closure. This is because IOLs are thinner than the natural lens. So RLE or cataract surgery creates more space for fluid circulation in the front of the eye.

How can I reduce the risk of problems?

Most patients have IOL implantation under local anaesthetic. You can eat and drink normally before surgery, and should take any regular medication as usual.

Mr. David performs most RLE and cataract surgeries under "topical" anaesthesia". This means a nurse will administer anaesthetic eye drops to the surface of the eye which makes it numb. This has the additional benefit of avoiding a ptoentially uncomfortable injection adjacent to the eye.

Keep your breathing calm, stay as relaxed as you can, and try to keep your head still after Mr. David has positioned it comfortably. You can help your surgeon apply the drape and stick your eyelashes out of the way by opening both your eyes wide at the beginning of surgery. Blinking is no problem after the draping is complete. Just look straight up ahead to the bright operating light with both eyes open, but blink when you need to. Looking up to the bright microscope light helps to keep your eyes in the best position.

Let Mr. David know if you feel any discomfort, and tell your surgeon if you need to cough, sneeze or take a break. Try not to squeeze the eyes shut, but blink whenever you need to. A clear plastic shield is normally taped over the eye at the end of surgery to protect the eye on the way home. Nursing staff will show you how to wear the eye shield at night (normally for one week after RLE). You can wash and shower normally from a few days after RLE. Most surgeons recommend no swimming for a week and no contact sports for a month. Noncontact sports such as gym and jogging can be resumed two weeks after surgery. Mr. David will advise you when it is safe to start driving again. Typically this is within a few days of surgery.

Set a smart phone reminder and use the antibiotic and anti-inflammatory drops as prescribed to help the eyes to heal well. It is good to leave at least two minutes between different types of eye drop so that they each absorb well before the next drop is applied. If you miss the first time or you are not sure, applying a second eye drop is no problem. Some variability of vision and comfort is normal in the early weeks after RLE, and patience is required. But discomfort is usually mild, and vision normally recovers substantially within two to three days once the pupil dilating drugs have worn off.

Report to your surgeon or an eye casualty department without delay if you have increasing aching pain, light sensitivity, redness, blur after surgery. Other danger signs, particularly relevant to highly myopic (shortsighted) patients undergoing RLE, relate to the warning signs of a retinal detachment. These are a sudden new shower of floaters, flashes of light (even with the eyes closed) and visual field loss (a shadow or curtain spreading across your vision). Most retinal detachments can be repaired without detriment to your vision, but the chances of success are much higher if the detachment has not spread across the centre of your vision. You may not be aware of a problem that requires treatment in the healing phase. So make sure you attend your review appointments even if your eyes feel good.

How much does RLE cost?

Surgery to correct the need for glasses or contact lenses is not available as an NHS procedure and is either not covered or only ocvered in part by private health insurance schemes.

The total cost of surgery is directly dependent on the type of lens implant used. Please email us via the "contact us" page for an exact quote.

Please see below for a brief animated video on RLE