Lens Implants and replacement surgery
Laser procedures such as the LASIK procedure, which work by reshaping the cornea of the eye have helped patients mainly below the age of 45 to see better. However, they are not a suitable alternative for every patient and laser surgery is permanent and cannot be reversed. Intra-ocular lens implant surgery uses similar surgical techniques to those required for cataract surgery in which the natural lens of the eye is replaced with an artificial lens.
Different Types Of Lens Implants
Lens implants can be catagorised into two main types:
- those where the natural lens of the eye is retained - ‘Phakic’ or ‘Implantable Contact Lenses" (ICL’s)
- those were the natural lens of the eye is replaced - Refractive Lens Replacement Surgery (RLR)
Phakic (ICL) Lens Implants
Phakic ICL’s work like a contact lens, but instead of being placed on the surface of the eye, it is surgically placed inside the eye. These implants are options for younger and middle aged patients with severe myopia because the lenses of their eyes are still elastic and have not yet lost their ability to accommodate (they are able to see at close distances without the need for reading glasses). With the aid of ICL’s these patients can reduce their dependency on spectacles or contact lenses while conserving the ability of their natural lenses to accommodate for close-up vision.
The disadvantage of the phakic ICL is that surgery is intra-ocular (like a cataract operation). A remote chance that surgery may introduce an infection into the eye does exist. Other surgery related complications are possible. In some patients problems with night vision and glare have been reported. Less glare and haloes are experienced when compared to the glare often associated with LASIK.
Different types of phakic ICL lens implants exist, including bifocal lenses and lenses to correct hyperopia and astigmatism.
Procedure
Drops are placed in the eye to dilate and numb the eye. After a tiny incision is made in the cornea the surgeon begins to insert the ICL (which is foldable) with a special lens insertion instrument. Most procedures take just 10 minutes to perform. After several hours the eye drops that dilated the eye, wear off and the pupil returns to it normal size.
Clear Lens Replacement Surgery also referred to as Refractive Lens Replacement Surgery (RLR)
For RLR surgery the eye’s natural lens is first removed with the aid of ultrasound, and then it is replaced with a synthetic lens. Various RLR options exist:
RLR Surgery utilising a FIXED-FOCUS Lens Implant
Patients suitable for this procedure include those with specific refractive disorders, such as high myopia. Often these patients are outside the treatment range for the LASIK procedure and yet a multi-focal lens implant may not be appropriate.
Fixed focus RLR is predominantly considered for patients who are more than 40 years of age and who do not object to the use of reading glasses. RLR is also used when an age related cataract already exists, which sooner or later would lead to an exchange of the body's own lens with a synthetic lens.
RLR Surgery utilising MONOVISION Lens Implants
Monovision is a technique where one eye is corrected for distance vision, and the other eye is corrected for near vision. Monovision allows us to see close objects clearly with one eye and distance objects clearly with the other eye. Monovision often enables us to see both near and far without the use of corrective lenses.
The patient’s brain automatically gets used to monovision within a few weeks. Most patients over the age of 40 who had monovision RLR surgery and who have taken the time to fully become accustomed to it, like it and find it very useful.
RLR Surgery utilising a MULTI–FOCAL Lens Implant (PRELEX) Surgery utilising a FIXED-FOCUS Lens Implant
PRELEX stands for PREsbyopic Lens Exchange, these days referred to as the surgical intervention which restores vision without glasses for hyperopic and presbyopic patients.
As we age our natural lens becomes less flexible and loses its ability to accommodate. As a result of this we are not able to see near objects clearly and require reading glasses. This condition cannot be corrected with the aid of laser surgery such as LASIK. Patients who have had laser vision correction will in later years develop presbyopia. This can be corrected with the aid of PRELEX surgery.
Multi-focal lens implants are not recommended for patients who do a lot of night driving. In some cases where multi-focal lenses have been implanted the reflection of light does cause haloes. Patients with small pupils need to be diagnosed properly in order to determine if PRELEX is a suitable alternative for them. After surgery patients must allow sufficient time for their vision to adapt and to adjust to the implanted PRELEX lens.
RLR Surgery utilising the Accommodative Lens Implant
The accommodative lens which is manufactured by Human Optics AG is the latest lens developed for RLR surgery. A healthy eye is able to change its shape in order to accommodate clear vision. The ability to “accommodate” deteriorates as we get older. Most artificial lenses, which are used for lens replacement surgery are rigid and cannot change their shape like the natural lens. As a result of this patients generally have to wear glasses after cataract or lens implant surgery. This disadvantage is overcome by means of the accommodative lens, which is able to maintain the accommodation on an artificial basis. This crystalline lens enables the patient to focus on far as well as near images.
The accommodative lens has been successfully implanted since the middle of year 2000. The accommodative lens is known to give excellent results with good far, near and intermediate vision, generally without the use of glasses.
Frequently asked questions
How safe are all the above procedures?
RLR uses new technology combined with a well proven surgical procedure. Every year millions of people undergo cataract surgery, in which the lens is replaced with a lens implant, using the same surgical techniques as those required for RLR.
As with all surgery there are risks, even though cataract surgery is now considered one of the quickest and safest surgical interventions available. The most common risks associated with RLR are: Retinal Detachment 0.01 % Infection - 0.03%; Macular Oedema; Floaters, Glare or haloes; Posterior Capsule Opacification (PCO), which can quickly be dealt with by means of an outpatient YAG laser treatment. Other possible complications include tearing of the lens capsule (less than 1%).
Do I need to be hospitalised for any of the mentioned surgical interventions?
No, all of the mentioned procedures are performed on a day surgery basis. The patient stay in the surgical clinic is normally less than 4 hours.
Is the procedure performed under general anaesthetic?
No, all the mentioned procedures are normally performed under local anaesthetic. In some instances the patient or the ophthalmic specialist may prefer to have the operation performed under a general anaesthetic.
Is it possible to correct presbyopia using lasers e.g. the LASIK procedure?
No. Laser vision correction changes the curvature of the cornea. As presbyopia is the deterioration of the eye’s ability to focus, surgery to the cornea will not correct this. However presbyopia can be corrected by means of RLR surgery utilising PRELEX or ACCOMMODATIVE lenses.
What advantages are associated with RLR in comparison to LASIK?
- Suitable for people with thin corneas or very high prescriptions.
- If the patient is already in their 40s or 50s, RLR vision correction will remain stable over time; whereas LASIK procedure patients can still go on to develop presbyopia as they age.
- You will never require cataract surgery later in life.
