PRELEX (presbyopic lens exchange) in Paris
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General information on PRELEX or clear lens extraction
The lens is one of the eye’s two natural lenses, the other being the cornea. Together, the lens and cornea are responsible for refracting light. By altering the direction of light rays, they allow images to be focused on the retina.
Refractive errors are known as “ametropias.” These include myopia (nearsightedness), astigmatism, hyperopia (farsightedness), and presbyopia. PRELEX (“presbyopic lens exchange”) is a refractive surgical technique that can correct these errors. The procedure was approved by the FDA in 1997 at the initiative of two American ophthalmologists. It consists of extracting the natural lens and replacing it with an implant tailored to the patient’s visual defect and required correction.
The surgical technique is exactly the same as that used in cataract surgery. In both cases, the lens is removed: in PRELEX, the lens is clear; in cataract surgery, it is opacified. Cataract surgery is the most commonly performed operation worldwide, making the technique highly refined and its results well understood.
In most cases, PRELEX does not add an extra surgical step to a patient’s journey. The vast majority of people will eventually require cataract surgery as they age. Once PRELEX has been performed, future cataract surgery is no longer necessary.
Indications for PRELEX
This technique can correct all refractive errors except certain forms of astigmatism (specifically “irregular astigmatism”) and very high myopia (due to the risk of retinal detachment).
A thorough preoperative assessment is essential. This involves precisely defining the optical characteristics of the required implant. Various tests are performed to rule out contraindications, including corneal topography and assessment of lens transparency. Other tests screen for possible corneal, lens, or vitreoretinal pathologies, as well as glaucoma.
The choice of implant model also depends on the preferred distance for vision, which may vary based on the patient’s profession (e.g., night drivers, pilots, photographers, painters). Psychological factors are also crucial and must be evaluated, as conditions such as depression, psychosis, or unrealistic expectations can hinder the neuro-adaptation required after lens implantation.
The PRELEX procedure
Preoperative instructions
- Patients who wear contact lenses must remove them at least 48 hours before surgery.
- Makeup (especially mascara) should be avoided for 3 days prior to the procedure.
- The day before and the morning of surgery, patients should shower with Betadine, including the face and hair, and rinse thoroughly.
- Patients must fast for at least 6 hours before surgery: no food, drink, or smoking.
Surgical steps
PRELEX is an outpatient procedure: patients can return home a few hours after surgery. The operation is painless, lasts only a few minutes, and is performed under local anesthesia (anesthetic eye drops, usually oxybuprocaine), sometimes supplemented by a mild sedative.
If both eyes require treatment, two separate surgeries are scheduled at least one week apart.
Before the procedure, eye drops are used to dilate the pupil (mydriaticum). Once anesthesia is effective, a soft eyelid speculum is placed to keep the eye open.
The surgeon makes two incisions, approximately 2.2 mm and 1.2 mm, in the capsule (the “lens sac”) that contains the lens. This allows the introduction of a phacoemulsifier, a device that breaks up the lens using ultrasound. The fragments are then aspirated, and the capsule is left in place.
The implant is then inserted and unfolds inside the capsule. The micro-incisions are self-sealing and do not require sutures.
At the end of the procedure, 1 mL of antibiotics is injected into the eye to reduce the risk of infection, and a protective shield is applied.
A different surgical method called SICS (“Small Incision Cataract Surgery”) may be used when the energy required for ultrasound would be excessive and could damage the eye. In this case, the lens is removed directly without phacoemulsification.
Postoperative care
- The patient must wear the transparent protective shield at night for one week but can remove it during the day.
- Postoperative treatment, consisting of eye drops, must be strictly followed for one month.
- Pain is almost nonexistent, but tearing and hypersensitivity are common on the first postoperative day. For several days, patients may experience glare and see halos. Visual improvement is gradual.
- Reading and computer work are permitted from the day of surgery, though some discomfort is normal at first.
- Normal activities can usually be resumed the next day. However, driving should only be resumed with the doctor’s approval. Makeup can be used again after one week, and sports, intense physical activity, and swimming are allowed after three weeks. Showering is permitted the day after surgery, but patients should avoid rubbing their eyes or getting water in them.
Results
The goal of the procedure is complete independence from glasses. This is achieved in about 95% of cases. The remaining 5% may still need glasses, mainly for precise and prolonged near vision in low light.
In the vast majority of cases, clear lens surgery yields excellent and stable results over time. If a multifocal implant is used, some cerebral adaptation is necessary, and optimal comfort is generally achieved after 1 to 2 months.
Complications are rare. Postoperative infection (endophthalmitis) occurs in 0.32% of cases. Systematic injection of antibiotics at the end of the procedure helps minimize this risk. Other, even rarer complications include retinal detachment, macular edema (Irvine-Gass syndrome), and corneal edema.
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Frequently asked questions about PRELEX
Can you return to work the day after PRELEX?
This depends on the type of work. For office jobs, patients can usually return the next day or within 48 hours. For outdoor professions, a wait of at least one week is necessary. For aquatic professions (divers, lifeguards), about a month’s wait is recommended.
What is implant dislocation?
During surgery, the implant is placed on the posterior part of the capsule that originally held the lens. In extremely rare cases, this structure can rupture and fall backward in the eye, taking the implant with it. Surgical intervention is then required. This rare complication is more likely in cases of high myopia or certain types of glaucoma.
Is it possible to be allergic to the implant?
This concern actually refers to Toxic Anterior Segment Syndrome (TASS). It is not a reaction to the implant itself (which is made of inert, well-tolerated material) but to the preservative solution in which the implant was stored before insertion. The best prevention is thorough rinsing of the implant before placement. Strict adherence to prescribed anti-inflammatory treatment during recovery is also essential.
Can the implant be felt in the eye after surgery?
Absolutely not. However, immediately after surgery, patients may feel a foreign body sensation in the eye. This is not due to the implant itself but to temporary irritation of ocular structures affected by the procedure.
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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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