Intraocular lens implants (IOL) in cataract surgery
Find out more about cataract treatments
What is cataract?
Cataract treatment
Introduction to intraocular lens implants
In the absence of an implant (aphakia), the patient will experience significant hyperopia of about +14 diopters. Biometry, a preoperative examination, is used to calculate the required implant for each eye. During the preoperative consultation, the most suitable implant type for the patient will be determined.
The artificial lens implanted cannot change shape through accommodation. Standard implants allow vision at only one distance (either far or near). Most often, the chosen implant will allow distance vision without glasses, with reading glasses needed for near vision, although other options exist.
Standard IOL implants
Standard intraocular lens implants correct myopia and hyperopia, but not astigmatism. There are many brands of lenses marketed by various manufacturers. Only the best, clinically proven implants are used. These implants are fully reimbursed by the French Social Security.
They are used in the majority of procedures, for patients without astigmatism who will wear glasses postoperatively for near vision.
Sometimes, in patients with high myopia who have been accustomed to seeing up close without glasses, it may be decided to leave a residual myopia of -2.5 diopters, allowing them to continue to see up close without glasses after surgery.
Standard intraocular lens implants can also be used to correct presbyopia using the monovision technique, correcting the dominant eye for distance vision and leaving the non-dominant eye with a myopia between -1 and -1.5 diopters. With both eyes, the patient can see both far and near without glasses. This is a commonly used and effective technique, mainly for patients who were previously myopic.
Toric lens implants
Toric lens implants correct astigmatism. They are custom-made to specifically correct myopia or hyperopia, as well as astigmatism, thanks to increased lens power along one axis. Preoperative calculations provide an axis for implantation, requiring precise positioning of the implant during surgery.
Toric lens implants have an additional cost of around one hundred euros.
Multifocal lens implants
These implants provide both distance and near vision. There are also multifocal toric lens implants that correct both distance and near vision in patients with astigmatism. There are different mechanisms of multifocality: diffractive and refractive implants.
- Diffractive implants consist of a series of concentric steps that split light into different focal points. Trifocal diffractive implants allow distance, intermediate, and near vision without glasses. The disadvantages of these implants are photic phenomena (halos, glare), which occur in about 10% of cases but are generally well tolerated.
- Refractive implants are composed of juxtaposed optical zones, usually arranged circumferentially, each with a different optical power.
The main drawback is that they require good pupillary dynamics (pupil contraction and dilation), meaning the pupil must be able to contract sufficiently for near vision and dilate for distance vision.
The choice of implant model will depend on the preferred vision distance, after discussion with the patient. The patient’s profession may guide the choice, as in the case of pilots, for whom multifocality is contraindicated; in such cases, standard or toric lens implants are recommended if astigmatism is present.
Other surgical techniques
Phacoemulsification cataract surgery is the technique used in almost all procedures performed in France today. It is the gold standard and the most effective technique for nearly all cases.
Femtosecond laser-assisted cataract surgery (femto-cataract)
Frequently asked questions
Are there different colors of implants?
Yes, there are yellow and “white” (colorless) implants. However, the color of the implant will never change the color of the patient’s eye, which is determined by the iris and its melanin content.
Colorless implants are often recommended for individuals whose profession requires accurate color perception, such as photographers or painters, as they provide greater visual clarity. In contrast, yellow implants help reduce photophobia.
The choice of implant color is made before the procedure, during discussions between the patient and the surgeon. If the patient has already had cataract surgery in one eye, it is preferable to choose a second implant of the same color to avoid visual imbalance.
In some cases, especially if there are signs of age-related macular degeneration (AMD), yellow implants are preferable. Regardless of color, most current implants provide UV protection.
What is the lifespan of an intraocular implant and when does It need to be replaced?
Intraocular lens implants have an extremely long lifespan, exceeding 100 years. In theory, whether for Prelex or cataract surgery, the artificial lenses implanted never need to be replaced.
However, sometimes the postoperative result is unsatisfactory. If the preoperative assessment was performed thoroughly by an experienced professional, this is rarely due to an error in calculating the required power. Most replacements are performed when the patient experiences intolerable halos.
Replacing the implant with a more suitable one can be discussed with the surgeon. However, this decision should be carefully considered, as intraocular lens exchange is a much more technical and delicate procedure than initial cataract or Prelex surgery.
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This page was written by Dr. Camille Rambaud, an ophthalmologist based in Paris and a specialist in refractive surgery.
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