Clear Lens Exchange

(refractive or presbyopic lens exchange)

Clear lens extraction is a surgical procedure designed to reduce or eliminate the need for distance glasses or contact lenses and it can be used to treat a wide range of far-sightedness and near-sightedness. Unlike other refractive procedures that change the shape of the cornea clear lens extraction corrects vision by removing the crystalline lens in the eye and replacing it with a new artificial lens of a different focusing power, much like what happens in cataract surgery. State-of-the-art ultrasound instruments are used to measure your eye for the correct lens power, taking your lifestyle and activities into consideration. These custom measurements are entered into sophisticated formulae to calculate your personal implant power.

Cataract surgery has been successfully performed for years and has been one of the major advancements in the restoration of sight in the last decade. The clear lens extraction procedure resembles cataract surgery however, in cataract surgery the removed lens is clouded whereas in clear lens extraction the removed lens is clear. Clear lens extraction has been performed extensively in Europe over the past ten years with excellent results in correcting moderate to high far-sightedness and near-sightedness with or without astigmatism. The number of clear lens extraction procedures performed in the USA has dramatically increased in the last few years due to the elevated interest in refractive correction procedures.

Cataract surgery involves both the cornea and lens and is the commonest operation done in the UK.

The Surgery (The phacoemulsification procedure)

The technique was introduced by Charles Kelman in the 1960’s but required technical improvement before its widespread adoption about ten years ago. It is a quantum improvement over extra-capsular surgery and de regeur for refractive surgery. its advantages stem from the tiny (2.8mm) incision needed. This induces very little astigmatism (termed "corneal corruption" by refractive cataract surgeons) and is much less traumatic to the eye than the comparatively giant incision it replaced.

The incision is completely filled intra-operatively by the phaco probe enabling exquisite control of the operation by the surgeon. Never before has the outcome of cataract surgery depended so much on the surgeon’s skill rather than by chance. The small incision does not generally need stitches and heals rapidly with good vision expected after a day or two (but improving over a couple of weeks).

Phacoemulsification or Phaco is the modern method for removing lenses utilising high energy ultrasound. Using this technology a cataract which measures 12mm in diameter and 4mm in thickness can be vacuumed through an incision which measures only 3mm or less! Basically, phaco uses a hollow needle which, when activated by the surgeon, vibrates at 40,000 times per second thereby emulsifying the lens. Emulsified lens material is aspirated through the hollow centre in the phaco needle and fluid is simultaneously infused into the eye in order to keep if “inflated” during surgery. Lenses CANNOT be removed by laser routinely at present.

An intraocular lens or implant is routinely implanted following removal of the natural lens. The surgery takes about 30 minutes.

Finally, phacoemulsification lends itself to other ways of improving outcome such as measures to reduce pre-existing astigmatism and to reduce the dependence on reading glasses by the use of multifocal or accommodating implants.

The Choice of Implant and Reading Vision

1. The traditional implant is monofocal (i.e. is only perfectly focused at one particular distance) and usually chosen for distance vision but for near the patient will need reading glasses even if they did not need them before.

2. The multifocal lens is made of either silicone or acrylic and has refractive optics consisting of concentric zones. The lens provides two separate areas in focus simultaneously. Previous versions of these lenses used to cause halos and glare but this has largely been eliminated. In one study of patients given a multifocal implant 80% did not need distance glasses and 40% did not need reading glasses at all (compared to nearly 100% needing reading glasses with monofocal implants).

   These are impressive results but they demonstrate that only a minority of patients can expect to be completely glasses free. The majority will enjoy reduced dependence on reading glasses but still need them for more taxing near activities. There are ways of reducing this dependence even further. Your surgeon will discuss with you whether you are suitable for these implants.

   Further information on the new varieties of multifocal implants is available on www.CustomMatchSolutions.com.

3. The accommodating implant is one of the newest types of implant. It is designed to change position in the eye when you try to read so you can have good distance vision and also good reading vision. The ability to read with these implants varies from person to person but on average give 1.4 dioptres of accommodation equivalent to a weak pair of reading glasses. Even if this type of implant does not work very well for you the end result would be little different from having a monofocal lens; also this lens does not degrade the quality of your vision or have an effect on night driving as may occur with multifocal lenses.

   Further information on the accommodative implant is available on www.thetetraflex.com.

   You may want to have a look at an interesting patient   testimonial regarding a Tetraflex implant, or a video of a Textraflex implant operation.