Definition : replacement of the natural crystalline lens with a multifocal or trifocal implant (PRESbyopic Lens EXchange). Corrects presbyopia, hyperopia or pre-existing myopia.
Price in Brussels : 3000 to 4000 € per eye.
Recovery : functional vision the day after surgery, stabilisation in 2 to 4 weeks. Neural adaptation to multifocal implants: up to 1 year, 6 months on average.
Main indications : hyperopic presbyopes over 45, myopic presbyopes seeking independence from glasses.
Contraindications : crystalline lens still flexible in too-young patients, active retinal pathology.
Key point : irreversible intervention that permanently prevents future cataract.
PRELEX stands for PRESbyopic Lens EXchange. It is the replacement of the natural crystalline lens, now rigid, with a multifocal or trifocal implant of the latest generation. Technically, it is the same procedure as cataract surgery: a phacoemulsification. What differs is the context: the crystalline lens is still transparent, but has lost its flexibility and can no longer focus up close.
A single procedure simultaneously corrects presbyopia, pre-existing hyperopia or myopia, and definitively prevents future cataract. The artificial lens does not age.[1]
Before. The lens has lost its flexibility, and sometimes its transparency. It is what limits near vision, and what will become a cataract.
After. The lens is replaced by a clear implant, held by two flexible haptics in the capsular bag. It does not age, and a cataract can no longer form.
This is an irreversible procedure. Removing a still-functional natural crystalline lens is a decision not to be taken lightly. That is why the selection criteria are strict and the preoperative exam particularly thorough.
For whom is PRELEX indicated?
PRELEX is for patients over 45 with established presbyopia, ideally associated with hyperopia or myopia. It is the reference solution for the hyperopic presbyope who wants to free themselves from all their glasses in a single procedure.
It is not indicated for patients too young whose crystalline lens still retains some flexibility. In that case, laser monovision may be an alternative to evaluate. The exam determines which option is best suited to the patient's precise profile.
Choosing the implant
Multifocal and trifocal implants. Simultaneously correct distance, intermediate and near vision. In properly selected patients, the majority do without their glasses for most everyday activities. They can generate night light halos in the first weeks, which fade progressively with neuroadaptation.[2]
EDOF implants. Extended Depth Of Focus: an extended range of vision from distance to intermediate, with fewer halos. Suitable for patients who drive a lot or work intensively on screens, and accept light glasses for fine reading.
Monofocal implants in monovision. For patients who prefer to avoid any risk of halos: one eye corrected for distance, the other for near. An optically simpler solution, at the cost of a slight binocular asymmetry.
Recovery
Recovery is fast. Vision improves from the next day. Complete stabilisation takes two to four weeks. Neuroadaptation to multifocal implants, when needed, generally takes one to three months.[3]
What can really be expected
For properly selected patients with a quality multifocal implant, the majority of patients do without their glasses for most everyday activities.
But "doing without glasses" does not mean "perfect vision in every condition all the time". Certain situations, such as prolonged fine reading, very low light or intensive night driving, may still occasionally require slight correction.
This is a reality I systematically explain before the procedure. An informed patient is a satisfied patient.[2]
PRELEX and cataract: what difference?Technically, it is the same procedure. In cataract, the crystalline lens is opacified and must be removed. In PRELEX, it is still transparent but rigid. It is an elective decision, made to gain visual autonomy.
References
Brenner LF, Nistad K, Schonbeck U. Rethinking presbyopia: results of bilateral refractive lens exchange with trifocal intraocular lenses. Br J Ophthalmol. 2023;107(7):912-919. doi:10.1136/bjo-2021-320505.
Cochener B, Lafuma A, Khoshnood B, Courouve L, Berdeaux G. Comparison of outcomes with multifocal intraocular lenses: a meta-analysis. Clin Ophthalmol. 2011;5:45-56. doi:10.2147/OPTH.S14325.
Nishi Y, Nishi H, Fukui M, Tatsumichi M, Nishi K. Clinical assessment of brain adaptation following multifocal intraocular lens implantation. BMC Ophthalmol. 2025;25:116. doi:10.1186/s12886-025-03946-8.
PRELEX is performed on an outpatient basis: you go home the same day. The procedure lasts about 15 to 20 minutes per eye. The two eyes are operated on a few days apart.
In the first days, vision can be slightly blurry or hazy: this is normal and transient. Light activities (reading, television, walking) are possible from the next day. Driving is allowed as soon as vision is sufficient, generally within the first week.
Visual stabilisation is progressive over four to six weeks. Neuroadaptation to multifocal implants takes two to three months. During this period, night light halos may be perceived; they fade in the vast majority of cases.
Frequently asked questions
What patients often ask
Does PRELEX free you from glasses?
For properly selected profiles, the majority of patients do without their glasses for most everyday activities.
Is PRELEX irreversible?
Yes. Once the natural crystalline lens has been removed, it cannot be put back. The artificial implant, however, can be exchanged if needed.
What is the difference between PRELEX and LASIK for presbyopia?
LASIK monovision is less invasive, suitable for patients aged 40-50. PRELEX replaces the crystalline lens and is the reference solution after age 50.
Can you have PRELEX if you are myopic?
PRELEX is mainly for hyperopic presbyopes, but it can be considered in some myopic presbyopes wishing to free themselves from all their corrections. The preoperative exam determines whether PRELEX or another technique is more appropriate.
PRELEX and cataract: what is the connection?
By replacing the natural crystalline lens with an artificial implant during PRELEX, the possibility of developing a cataract in that eye is definitively eliminated. This is an often underestimated advantage: patients who undergo PRELEX will never need cataract surgery.
ASSESSING YOUR PRELEX CANDIDACY
PRELEX is an important decision that deserves complete information and a thorough exam. The initial consultation allows your refractive profile, the state of your crystalline lens and your visual expectations to be evaluated. It is available in Brussels within one to two weeks. If you are a candidate, the complete preoperative exam will be scheduled during this same consultation.
Halos and neuroadaptation
Recovery, halos and neuroadaptation
In the first days following the procedure, a light eye shield is worn at night. Vision can be slightly blurry or unstable for a few days: this is transient and expected.
The phenomenon most often reported by patients with trifocal implants is the perception of light halos around light sources (car headlights, streetlights, screens), especially at night. These halos are linked to the very nature of multifocal optics: the implant simultaneously distributes light between several foci (distance, intermediate, near), and the brain must learn to select the relevant image and ignore the others. This process is called neuroadaptation. It varies from one patient to another: some complete it in a few days, others in two to three months. In the vast majority of cases, halos fade significantly with time.
An alternative to trifocal implants exists: EDOF implants (Extended Depth of Focus). Their main advantage is less generation of night halos. In counterpart, near vision is often less sharp than with a trifocal implant, and their indication depends on the anatomy of the eye. The choice between trifocal and EDOF implant depends on your starting correction, your eye anatomy and your visual priorities.
Author of this page
Dr Serdal Sanak
Ophthalmic surgeon · Refractive and cataract surgery
CHIREC Hôpital Delta, Brussels
Graduated from the ULB, trained at CHU de Liège and CHIREC. European Diploma in Ophthalmology (FEBO). Refractive and cataract surgery make up the bulk of my operating activity, with procedures every week at CHIREC Delta. Dual specialisation: corneal laser surgery (Femto-LASIK, PRK) and intraocular surgery (ICL, PRELEX, cataract). Consultations in French, Dutch, English, Turkish, Kurdish, Persian and Italian.
