Refractive Lens Exchange (Clear Lens Extraction) for Myopia Correction

Updated: Feb 13, 2024
  • Author: Sanchay Gupta, MD, MBA; Chief Editor: Hampton Roy, Sr, MD  more...
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Overview

Background

Refractive lens exchange (RLE), also called clear lens extraction, seeks to modify the focusing power of the eye by removing the clear or nearly clear (noncataractous) natural lens of the eye and replacing it with an intraocular lens (IOL). [26]

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Problem

In refractive surgery, the properties of the cornea and/or lens can be surgically modified to better focus light onto the retina and decrease reliance on glasses or contacts.

Examples of refractive procedures targeting the cornea include:

  • Laser-assisted in situ keratomileusis (LASIK)
  • Photorefractive keratotomy (PRK)
  • Small incision lenticule extraction (SMILE)

Examples of refractive procedures targeting the lens include:

  • Phakic intraocular lenses (eg, with insertion of the Visian IOL lens implant between the posterior surface of the iris and anterior surface of the lens) [28]
  • Procedures to remove the crystalline lens
    • Cataract surgery is removal of the lens that is sufficiently cloudy that it impairs quality of vision even with glasses and impacts quality of life.  The procedure typically is eligible for insurance coverage.
    • Refractive lens exchange is removal of the clear or minimally cloudy lens to reduce or eliminate need for glasses and contact lenses. This is not eligible for insurance and is an out-of-pocket procedure.

It has become recognized that the crystalline lens of the individual over age 40 is “dysfunctional” in one or more ways. First, it becomes presbyopic, ie, loses the ability to accommodate, necessitating the use of reading or bifocal glasses or some other form of correction to provide near vision. [30] Second, the lens begins to develop some subtle but real clouding that can begin to impair quality of vision, even with optimal correction with glasses or contact lenses. [30] This has heightened interest in performing refractive lens exchange in patients before a “true “cataract forms, with a goal of improving sharpness and range of uncorrected vision.

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Epidemiology

In the United States, estimates of myopia prevalence range from 20-42%, with higher rates of nearsightedness observed among Asian and Hispanic ethnic groups and lower rates among African Americans and Caucasians. [31, 32] According to the World Health Organization, the prevalence of high myopia is projected to increase from 2.2% to roughly 10% of the world’s population by 2050. [33]

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Etiology

The etiology of myopia is complex. It is believed to be associated with a combination of both genetic and environmental factors such as prolonged near work, limited time spent outdoors, and diet. [34, 35, 36, 37, 38]  

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Pathophysiology

The cornea and the lens are the two optical components of the eye that are responsible for focusing light onto the retina. In hyperopia or farsightedness, the cornea-lens system is too weak relative to the axial length of the eye such that the image is focused behind the retina. In myopia or nearsightedness, the cornea-lens system is too powerful relative to the axial length of the eye, resulting in light being focused in front of the retina. [30]  

The majority of patients with myopia have axial myopia, where the cause of their nearsightedness is increased axial length, sometimes accompanied by increased corneal power. Myopia can also be acquired through changes in lens or corneal shape (as seen in anterior lenticonus or keratoconus) or after surgeries that artificially induce elongation of the eye such as scleral buckles used for retinal detachment repairs.   

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Presentation

Myopia typically develops in a progressive fashion through childhood or adolescence and stabilizes in early adulthood. It presents as blurry uncorrected distance vision.

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Relevant Anatomy

The natural lens sits inside of a capsular bag behind the iris. The capsule is suspended in the eye through circumferential attachments to the ciliary body by zonular fibers. In RLE, the natural lens of the eye is replaced by an artificial IOL that is placed inside the capsule to provide the desired visual correction.

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Indications

Broadly speaking, RLE is employed for correction of myopia, hyperopia, astigmatism, and/or presbyopia when alternative refractive options cannot sufficiently address the patient’s refractive error.

Most commonly, this would include patients over 45-50 with high myopia (> ~6 diopters [D]) or hyperopia (>~2 D) who may not be good candidates for corneal refractive procedures or the Visian ICL, or in whom early crystalline lens clouding is present. [39]

Reasons to consider RLE even in low myopia or hyperopia would be to:

  • Correct for presbyopia at the same time with the use of a multifocal lens, extended depth of focus (EDOF) lens, or monovision
  • Eliminate the need for cataract surgery in the future
  • Handle scenarios where corneal refractive surgery is less desirable (abnormal corneal anatomy, poor corneal healing, persistent dryness)
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Contraindications

In patients with high myopia, there is a greater risk for retinal detachment after lens extraction. [41] If pre-existing areas of vulnerability are noted such as lattice degeneration or holes, breaks, or tears, patients should be evaluated by a vitreoretinal specialist prior to proceeding with RLE.

RLE may not be beneficial in eyes where visual potential is limited by other comorbidities.

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Patient Education

There are three critical elements in counseling patients who are considering undergoing refractive lens exchange:

  1. The range of lens implant options. This is challenging because of the complexity of explaining presbyopia and the advantages and side effects of various lens implant designs. 

    Lens implant choices can be grouped in these broad categories [42] :

    • Monofocal (single-focus) designs that provide focus at one distance. These provide the sharpest vision, but, if the patient desires freedom from glasses, monovision (one eye for distance and one for near) is required. This can be tested preoperatively with a several-day trial of contact lenses to determine if the patient is a candidate for this option.
    • Extended depth of focus (EDOF) lenses. These provide vision at distance and intermediate range (eg, computer). Certain designs are relatively free from glare, whereas others provide higher contrast vision but create some glare and starburst that is most commonly seen at night around car headlights and streetlights. Patients implanted with these lenses typically will require glasses for reading at near.
    • Trifocal lenses provide uncorrected vision over the full range--distance, intermediate, and near--but again they create glare and starburst around lights. Sharpness of vision is slightly less than with the prior two lens designs.
    • A new option is lens implants whose power can be modified postoperatively to try to provide the patient with the maximal acceptable range of vision.  These are monofocal designs, and hence some form of monovision is required for reducing or eliminating the need for reading glasses. The advantage is that patients can live with vision after one or more adjustments in order to ascertain the optimal balance of distance and near vision for each eye.
  2. Possible need for additional postoperative procedures to refine the outcome: postoperative follow up is important to ensure that the refractive accuracy of the procedure is acceptable and that the patient’s visual goals have been met. A small percentage of patients might require corneal refractive surgery to treat any residual nearsightedness, farsightedness, and/or astigmatism.
  3. Success and potential complications: RLE has a high success rate, greatly reducing or eliminating patients’ need for glasses and contact lenses postoperatively. That said, patients should be advised of the symptoms of postoperative complications (see below) that might occur and the importance of immediately contacting their physician if new visual symptoms arise.
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