Refractive Lens Exchange (RLE), also known as Clear Lens Exchange (CLE), is a surgical procedure to correct refractive errors in which the natural lens of the eye is removed and replaced with artificial intraocular lens. This surgical procedure is very similar to cataract surgery, however in cataract surgery the lens is clouded, whereas in this surgery, the clear lens is removed.
The natural (crystalline) lenses of your eyes are located behind the iris, the coloured part of your eye. The lens is a curved flexible structure that changes shape to accurately focus an image on the retina, a photosensitive layer in the back of the eye. The natural ageing process of the lens causes stiffness (presbyopia) or clouding (cataract) of the lens, which affects clarity of vision.
In refractive errors such as hyperopia (farsightedness), myopia (near-sightedness) and astigmatism, the light entering the eye is not focused clearly on retina because the refractive components of the eye (cornea and lens) are either too weak or too strong to focus light properly. Refractive lens exchange procedure corrects the error and focuses the light on the retina by removing the natural lens in the eye and replacing it with a new artificial lens, thus reducing or eliminating the need for additional glasses or contact lens.
What are the indications for RLE?
Refractive lens exchange is used for correction of farsightedness, near-sightedness, astigmatism and presbyopia (diminished ability to focus on near objects) that is not easily managed by other refractive procedures. People over age 55 years with these refractive errors may have mild cataract that over time will gradually worsen and cloud the eye’s natural lens, causing blurred vision. In such cases a refractive lens exchange will allow correction of refractive error in advance of waiting for the cataracts to develop enough to require cataract surgery.
Though presbyopia may be corrected by glasses, a more permanent solution is offered through a procedure called PRELEX (presbyopic lens exchange). This is a type of refractive lens exchange procedure, which involves the removal of the natural lens and replacement with an artificial lens to correct presbyopia as well as cataract, if also present. With correction of presbyopia, the aim is to give both distance and near vision. To achieve this, multifocal or monofocal lens implants may be used for replacing the natural lens. If multifocal lenses are used, a configuration called “monovision” or “blended vision” may be used.
With monovision corrections, one eye (usually the dominant eye) is corrected for distance vision. The non-dominant eye is corrected for near vision. The visual system behaves differently from person to person. Some people can tolerate monovision (MV), in that the brain can blend the images and obtain sharp distance and near vision despite the eyes being of different focal lengths.
With multifocal lens implants, both eyes should be operated on for the best results. These implants work well when the eye is otherwise normal. Their function is compromised if there is coexisting macula disease or dry eye. In addition, the visual system needs to be well aligned with the pupil for successful results. Your visual needs and usual tasks are taken into account. Dr Chiu will perform testing to help determine your suitability. If you are a good candidate for multifocal intraocular lens implants, and you elect for this surgery, halo and glare are a common side effect. In most people these diminish over time. Dr Chiu will discuss this treatment option with you in detail.
Who is a good candidate for the procedure?
The most suitable candidates for RLE surgery are those aged 55 years or more, where the lens is no longer working and cataract will be already developing or is imminent. Also, those aged 21 years or more, who are not suitable for laser vision correction and implantable collamer lenses (ICL) are also suitable for RLE.
What are the preoperative procedures?
Before the surgery, tests such as visual acuity, slit lamp examination, and dilated examination are performed. In visual acuity test you will be asked to read the smallest letters that you can see on the standardized chart (Snellen chart). The slit lamp examination uses a special microscope (slit lamp) that provides a detailed view of the different parts of the eye. During the exam, Dr Chiu will look at the front parts of the eye including the clear outer covering (cornea), the lens, and the coloured part (iris). Dilating drops may be used to allow a full view of the back of the eye. Special lenses are used with the slit lamp to view deeper structures of the eye, such as the retina and the optic nerve..
In order to obtain accurate measurements of the eye, to calculate the custom lens for your eye, it is recommended that you stop using contact lenses 1 week prior to your appointment.
How is the surgery performed?
The RLE procedure usually takes about 20 minutes and is performed under a local anaesthesia, either by way of topical anaesthesia (eye drops) or anaesthetic ‘block’. Once the eye is numb, a tiny incision is made in the periphery of the cornea. The surgery is microincisional, or like keyhole surgery. The lens capsule is opened, then Dr Chiu uses an ultrasound probe to break up the lens, which is then removed by suction. This process is called phacoemulsification. Then the artificial lens is introduced inside the eye and positioned in the same lens capsule that surrounded the natural lens prior to it’s removal. The incision heals on it’s own and does not require any sutures. Dr Chiu places antibiotic into the eye to prevent infection, which can be vision-threatening, and a patch and shield over the eye to protect it. After the surgery, you may experience mild foreign body sensation in the eye, for example the eye may feel gritty like there is an eyelash in it. Please do not rub your eye.
What are the postoperative instructions?
Following surgery your doctor will prescribe eye drops to prevent infection and control inflammation. Rubbing or pressing on the eye, getting water in the eye and swimming should be avoided. A follow up visit is scheduled to monitor healing and to check for vision.
What are the risks and complications?
The possible complications associated with RLE are infection, swelling of the eye structures, detached retina, and a temporary increase in intraocular pressure. In some cases, posterior capsule opacification, a hazy membrane (capsule) just behind an intraocular lens implant may develop after several months following RLE surgery. This may cause blurred vision or glare symptoms. This can be corrected by Dr Chiu by a procedure known as YAG capsulotomy, where the lens is polished using a laser.