Refractive Lens Exchange (RLE) vs. Phakic Intraocular Lenses (PIOLs)

Refractive errors such as myopia, hyperopia, and astigmatism are common vision problems affecting a significant portion of the population globally. Corrective eyeglasses or contact lenses are often the first-line solutions for those struggling with poor eyesight due to refractive errors.

However, newer refractive eye surgeries provide permanent ways to eliminate dependency on vision correction aids. Today's two major procedures are Refractive Lens Exchange (RLE) and Phakic Intraocular Lenses (PIOLs) implantation.

Both surgeries effectively correct refractive errors but have relative advantages and disadvantages. This article explores RLE and PIOLs, comparing indications, procedural steps, benefits and risks, safety profiles, visual outcomes, and more between the two options.

1. Indications

RLE and PIOLs represent significant advancements in vision correction technology. These procedures offer life-changing solutions for those struggling with various refractive errors, providing clearer vision and a new perspective on life.

Refractive Lens Exchange (RLE)

RLE is an eye surgery predominantly employed to correct refractive visual errors, including myopia (nearsightedness), hyperopia (farsightedness), and presbyopia (age-related loss of near vision).

The procedure is mainly considered for patients over 40 without fully developed cataracts and are unsuitable candidates for laser eye surgery like LASIK. It's a viable option for individuals with higher levels of myopia, although the risk of retinal detachment should be carefully weighed in these cases.

RLE is also suitable for patients with a healthy tear film who are free from significant ocular comorbidities that might impede healing, such as iritis, corneal guttata, uncontrolled glaucoma, or uncontrolled diabetes.

Phakic Intraocular Lenses (PIOLs)

PIOLs are primarily utilized to correct moderate to high myopia and myopia with astigmatism. These lenses are particularly favorable for younger patients who have high prescriptions and are found unsuitable for other laser surgical options such as LASIK. PIOLs, often considered a form of permanent contact lens within the eye, are a common choice for patients who seek an alternative to corneal refractive surgery.

The ideal candidates for PIOLs are usually younger, typically above 18 years old, with a stable prescription for at least 12 months before the surgery. They should not have significant ocular surface or corneal abnormalities. PIOLs can correct a wide range of refractive errors, including myopic errors up to -17.00D, hyperopic errors up to +10.00D, and astigmatism up to +/- 4.50D.

In some cases, the range of correction achievable through PIOL procedures can be extended with the help of supplemental laser refractive surgery. Potential candidates must have stable refractive errors and no recent significant changes in their prescription.

2. Procedure

RLE and PIOLs are two distinctive procedures that address a broad spectrum of visual impairments, allowing patients to see the world more clearly and vividly. Here's how these procedures are performed.

Refractive Lens Exchange (RLE)

The surgical procedure for RLE closely resembles cataract surgery and is used to correct various refractive errors. In RLE, the eye's natural lens is replaced with an artificial IOL tailored to the patient's specific visual requirements.

Procedure Steps for RLE:

1. Pre-Operative Evaluation: Patients undergo a detailed eye examination to assess their suitability for RLE and discuss the various IOL options. Factors like lifestyle, visual needs, and personal preferences are considered to select the most appropriate IOL type.
2. Anesthesia and Incision: The procedure starts with administering anesthetic eye drops to numb the eye. A small incision is made where the sclera meets the cornea.
3. Lens Removal: The natural lens of the eye is broken down using a technique called phacoemulsification. This involves using ultrasound waves to fragment the lens, which is then aspirated out of the eye.
4. IOL Implantation: The selected IOL is inserted through the same incision and positioned within the lens capsule, replacing the natural lens.
5. Closure and Protection: The incision typically heals naturally without stitches. A protective shield is placed over the eye during the initial recovery period.

The entire RLE surgery usually lasts about 15 to 30 minutes. Following the procedure, patients might experience temporary visual disturbances and are advised to arrange for transportation as they cannot drive immediately after the surgery.

Phakic Intraocular Lenses (PIOLs)

PIOLs implantation is a surgical procedure to correct significant refractive errors. Unlike RLE, the eye's natural lens is not removed; instead, the PIOLs is added to the eye to work with the natural lens.

Procedure Steps for PIOLs:

1. Preoperative Assessment: A thorough examination ensures the patient's eyes are suitable for PIOLs implantation. Eye measurements are taken to choose the right lens size and type.
2. Anesthesia and Incision: The patient receives local anesthesia to numb the eye. A small incision is made, typically at the edge of the cornea.
3. Lens Placement: PIOLs are carefully inserted into the eye. The exact placement depends on the type of PIOLs - it can be positioned either in front of the natural lens (in the posterior chamber) or attached to the iris (in the anterior chamber).
4. Adjustment and Closure: The lens is precisely positioned and aligned within the eye. In most cases the incision heals naturally without stitches.

3. Advantages

RLE and PIOLs are groundbreaking procedures that offer a range of benefits to people seeking freedom from glasses or contact lenses. Here's an overview of the advantages these surgeries provide.

Refractive Lens Exchange (RLE)

• RLE can correct presbyopia, high hyperopia, and myopia, often when LASIK or other laser surgeries are unsuitable.
• The intraocular lens used in RLE does not change over time, offering a long-lasting solution and the best vision quality.
• RLE eliminates problems such as headaches or eye strain associated with spectacles and other corrective lenses, providing more comfort.
• RLE can be the best option for patients with severe refractive errors or corneal issues where other procedures are inappropriate.
• Recovery from RLE is typically quick, with many patients resuming normal activities within a day and reporting immediate vision improvement.
• RLE eliminates the potential for developing cataracts in the future, as the artificial lens does not age or change like natural lenses​

Phakic Intraocular Lenses (PIOLs)

• PIOLs can treat more myopic and hyperopic refractive errors than corneal refractive surgery.
• PIOLs generally provide high optical quality and the potential for better-uncorrected vision than pre-surgery corrected vision.
• Implanting a PIOL preserves corneal tissue and biomechanics, avoiding the risk of ectasia and maintaining the natural corneal shape.
• The procedure is reversible; the lens can be removed or replaced.
• Since the eye's natural lens is retained, accommodation (the ability to focus on near objects) is preserved​.

4. Disadvantages

Despite the numerous advantages, RLE and PIOLs are not without their drawbacks. It's crucial to weigh these disadvantages before deciding on the procedure.

Refractive Lens Exchange (RLE)

• RLE may not be suitable for certain eye conditions and is generally not recommended for myopia when other options like LASIK are available.
• RLE is more invasive than other vision correction procedures, such as LASIK or PRK, and carries risks associated with lens removal.
• In some cases, additional treatment may be required after RLE to achieve a clear vision fully.
• RLE is typically more expensive than other eye surgery options like LASIK​

Phakic Intraocular Lenses (PIOLs)

• With age, the anterior chamber may be shallow, affecting the placement and performance of the PIOL.
• Particularly in sulcus-supported PIOLs, there is a risk of developing cataracts over time.
• This is a concern, especially for anterior chamber PIOLs, where there can be a steady loss of endothelial cells.
• Patients may experience night-time symptoms like glare and halos, especially those with larger pupil diameters.
• These can include pigment dispersion, glaucoma, and PIOL dislocation or decentration.​

5. Safety and Complications

RLE and PIOLs are generally safe, but it's essential to understand the potential risks and complications associated with this procedure. This knowledge helps patients make informed decisions.

Refractive Lens Exchange (RLE)

Safety of RLE

RLE is considered a safe and well-established procedure, similar to cataract surgery. The success and safety of RLE depend on factors like the surgeon's experience, the technology used, and the patient's health and eye condition. Choosing a skilled surgeon and a personalized approach to RLE increases the procedure's safety.

Risks and Complications of RLE

Common risks and complications associated with RLE include:

• Infection: A small risk exists, but following post-operative care instructions and keeping the eye clean can minimize it.
• Visual Disturbances: Glare and halos are possible, especially in low-light conditions. These usually improve during the healing process but can sometimes persist.
• Retinal Detachment: Particularly in individuals with high myopia or a family history of retinal issues.
• IOL Displacement: In rare cases, the implanted IOL may become displaced, requiring additional surgery.
• Dry Eyes: Can occur temporarily or persistently after surgery.
• Other Complications: Including the need for multiple surgeries or additional vision correction methods in some patients​​​​​​.

Phakic Intraocular Lenses (PIOLs)

Safety of PIOLs

PIOLs implantation is generally a safe procedure. However, as with any intraocular surgery, it carries risks. These risks can be minimized with careful patient selection, proper surgeon training, and adherence to recommended surgical protocols.

Risks and Complications of PIOLs

Common risks and complications associated with PIOLs include:

• Visual Disturbances: Blurred or cloudy vision, mainly due to residual refractive error or other complications like cataracts.
• Endothelial Cell Loss: A concern in all eye surgeries, but endothelial cell counts have been stable in studies.
• Cataracts: Especially in older patients or those with high myopia.
• Retinal Detachment and Cystoid Macular Edema: Less likely than other intraocular surgeries.
• Lens Repositioning, Removal, or Replacement: As with any implant, may be required.
• Corneal Decompensation: Not commonly seen with PIOLs but still a possibility.

To avoid complications, surgeons must be well-trained and experienced, especially in the initial learning phase of the procedure. Patient selection is critical, with a preference for motivated, well-educated patients with reasonable expectations and favorable anatomy​​​​​​​​​​​​​​.

6. Visual Outcomes

Both procedures have been associated with excellent visual outcomes. This section highlights how RLE and PIOLs can significantly improve vision, drawing on recent studies and patient experiences.

Refractive Lens Exchange (RLE)

A study evaluating visual outcomes after RLE with a single-piece diffractive multifocal intraocular lens showed that most patients achieved good uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and near visual acuity (UNVA).

Postoperatively, 53% and 91% of eyes achieved a mean manifest refraction spherical equivalent (MRSE) of ±0.25 D and ±0.50 D, respectively. Additionally, 74% and 96% of eyes had a UDVA of 20/20 or better, and 85% and 96% achieved a UNVA of 20/32 or better.

Another study investigating RLE with bilateral implantation of a trifocal intraocular lens in patients with presbyopia found high patient satisfaction. Postoperatively, 100% and 92% of eyes were within ±1.00 D and ±0.50 D of emmetropia, respectively. Furthermore, 77% of patients reported complete spectacle independence, with 87% and 90% stating they were satisfied with their vision and would recommend the procedure to others, respectively.

Phakic Intraocular Lenses (PIOLs)

Studies show that the postoperative UCVA is 20/20 or better in 97% of cases at 1 month and 100% at 3, 6, 12, and 36 months postoperatively​​.

The efficacy index of posterior chamber phakic IOLs was 0.8 (mean UDVA postop/ mean CDVA postop), indicating a good visual outcome. About 73% of the eyes were within ±1.00 D (spherical equivalent) of the attempted correction​​.

In comparison with other refractive surgeries, PIOLs, particularly the implantable collamer lens (ICL), have been found to have better visual outcomes compared to LASIK and PRK, especially in patients with high myopia. They offer better contrast sensitivity, night-driving simulation, and UCVA. In a study comparing ICL with the small incision lenticule extraction (SMILE) surgical procedure, the ICL group exhibited significantly fewer higher-order aberrations and better-quality vision (decreased halos and starbursts)​​.

Wrap Up

RLE and PIOLs are viable surgical options to correct refractive errors without eyeglasses or contacts. RLE benefits presbyopic patients over 40 who are unsuitable for LASIK by exchanging the natural lens for an artificial one. PIOLs help younger patients with extreme myopia that laser surgery cannot treat by implanting a lens while retaining the natural one.

Both procedures enable good visual outcomes if performed carefully on suitable candidates. The choice depends on the patient’s age, eye condition, lifestyle needs, and specific refractive errors. RLE and PIOLs provide permanent vision correction with high success rates when customized appropriately.

Is RLE painful?

The procedure is generally not painful because numbing eye drops are used, and some patients may receive sedation.

What is the recovery time for RLE?

Most people can resume normal activities the following day, but full recovery and stabilization of vision might take several weeks.

Will I need glasses after RLE?

While many people do not require glasses after RLE, some may still need them for specific tasks, depending on the type of IOL used and individual healing.

Is PIOL implantation painful?

Like RLE, PIOL implantation generally involves minimal discomfort because of numbing eye drops.

Can PIOLs be removed or replaced?

Yes, PIOLs can be removed or replaced during cataract surgery or for lens exchange.