Frequently asked questions about intraocular lenses (IOLs) and refractive lens exchange (RLE)

What is an intraocular lens (IOL)?

An intraocular lens is a more or less technologically advanced artificial lens implanted in a patient’s eye after the patient’s own lens has been removed.

A modern intraocular lens is a lens made of plastic characterized, depending on the type, by different properties of focusing and scattering light. The lenses in use today are usually high-quality lenses built with a round main part and two arms (hapten), whose role is to hold the lens in the correct position.

When is an intraocular lens used?

Artificial lenses are implanted in patients suffering from cataracts and patients who do not qualify for laser vision correction. They are also being resorted to for people struggling with ametropia. Ametropia is a visual defect caused by an abnormal ratio between the focusing ability of the eye’s lens and the anatomical dimensions of the eye. Two artificial lenses can be used to correct severe ametropia – the latter to enhance the effect of the previously implanted intraocular lens. The secondary lens is implanted four to six weeks after the primary lens.

What is a retractable lens?

So-called retractable lenses are constructed of retractable silicone. They can be inserted into the eye during surgery through a small, two-millimeter opening. Healing of the surgical wound and vision rehabilitation thus take place very quickly.

What is RLE(refractive lens exchange) or CLE(clear lens extraction)?

Refractive lens exchange (RLE) is a procedure that involves removing a patient’s own lens and replacing it with a technologically advanced artificial lens to correct the visual impairment. CLE is a procedure that replaces the non-corrected lens with an artificial lens.

Can the procedure of replacing the natural lens with an artificial one also be carried out in patients who have previously undergone laser vision correction?

Among those coming in for cataract surgery are increasingly patients who have previously undergone laser vision correction. Previously performed laser vision correction is not a contraindication to having another eye surgery – cataract surgery involving removal of one’s own and implantation of an artificial lens. In calculating the power of the optical lens that will be implanted in our cataract surgery, the doctor will use the results of the patient’s examinations from the time before laser vision correction and those he will conduct for the now planned surgery.

Does the ophthalmologist have systems in place to help select the optimal lens for a cataract-laden eye that has already undergone laser surgery?

Yes. The state-of-the-art equations for correctly calculating the power of an implantable lens include:

• Double-K
• Hoffer Q
• Haigis-L
• Masket
• Koch and Wang

The Verion (Alcon) system, on the other hand, allows the power of the implantable lens to be calculated taking into account past surgeries or existing visual pathologies without the need to provide preoperative corneal data.

Why is it necessary to replace one’s own lens with an artificial one in the case of cataracts?

A cataract is an opacity of the lens that, if left untreated, leads to impaired vision that hinders daily functioning and often results in complete loss of vision. In the early stages of cataracts, drugs can be administered in the form of drops, but their action does not always have the desired effect. In fact, the only effective way to eliminate cataracts is through cataract removal surgery, that is, surgery to remove the crumpled native lens and implant an artificial intraocular lens.

What vision defects qualify patients who cannot undergo laser correction for refractive lens replacement?

Refractive lens replacement surgery is recommended for patients with severe farsightedness, presbyopia and astigmatism, and in some cases myopia.

The latest surgical technologies make it possible to combine cataract surgery with simultaneous removal of other visual defects, such as astigmatism or presbyopia.

Can the intraocular lens be replaced?

No. The artificial lens stays in the eye forever, so it is extremely important to calculate the implantable lens in such a way that it meets the patient’s needs to the maximum extent. Modern intraocular lenses are always selected according to the needs and expectations of patients, as well as the anatomical conditions of the eye.

What is the qualification for refractive lens replacement?

Qualification for the procedure includes:

• Patient Interview.
• Computerized eye examination (autorefractometry).
• Keratometry (measurement of the curvature of the cornea).
• Pachymetry (measurement of corneal thickness).
• Corneal topography.

You can find a list of pre-operative tests and more detailed information here.

What is a monofocal lens?

A standard monofocal lens (also known as an “amplification lens”) ensures that we can only see clearly at one distance. It is the only one reimbursed by the National Health Service. Implantation of a monofocal lens always results in the eye losing its ability to accommodate, which for people undergoing cataract surgery entails the need to wear nearsighted or nearsighted glasses – the choice is up to the patient.

Depending on the option chosen, the patient may experience less (aspheric lens) or more (spherical lens) image distortion at the periphery of the lens.

What is a multifocal lens?

Multifocal lenses, available at private clinics, restore patients’ full range of vision: for distance, near and intermediate distances. Implantation of multifocal lenses after removal of the cloudy natural lens in most cases allows patients to function in daily life without glasses, such as driving, reading books, typing on the computer or watching TV.

Multifocal lenses have a unique design that takes advantage of our brain’s ability to so-called neuroadaptation (it takes an average of one to three months, and even longer in some patients). They provide excellent vision quality and natural contrast sensitivity in both nearsighted and farsighted patients, as well as those with astigmatism.

The performance of multifocal lenses is very similar to progressive lenses used in spectacle vision correction.

Bifocal intraocular lenses (bifocals) have two foci, providing sharp vision at two distances – near and far.

Trifocal (trifocal) lenses refract light entering the eye from near, medium distance and far away and focus it in one focus on the retina. Thus, they guarantee good vision at close, medium and long distances.

What is a toric lens?

Single-focus toric lenses eliminate astigmatism, provide sharp vision for either distance or near, and multifocal toric lenses eliminate astigmatism, provide sharp vision for distance, near and intermediate distances.

What is an EDOF (extended depth of focus) lens

EDOF are intraocular lenses with extended depth of field (extended focal length), combining the advantages of monofocal and multifocal lenses. This means that they provide sharp vision over a wide range of distances – from far away to intermediate. EDOF lenses are an excellent choice for people who, due to their active lifestyles, value complete or almost complete freedom from glasses. They enable clear vision of objects at various distances: from far to intermediate distance (more or less at arm’s length).

Which intraocular lenses are referred to as PREMIUM?

Premium lenses meet the needs of increasingly demanding patients, guaranteeing excellent quality of life and visual acuity after cataract surgery – even without the need for additional glasses. Premium implants additionally allow:

• correction of astigmatism (toric lenses)
• correction of presbyopia (multifocal, or multifocal lenses)
• improvement of contrast vision (aspheric lenses)
• prevention of age-related macular degeneration – AMD (lenses with UV filter and blue light filter)

Why do artificial lenses have UV and blue light filters (blue light filter)?

The filters eliminate the harmful part of the light beam, protect on the retinal pigment epithelium and reduce the risk of developing macular degeneration (AMD), the most common cause of irreversible blindness in patients over 60. year of age.

Read more about state-of-the-art lens implants used in cataract surgery here here.

Read more about modern artificial lenses (IOLs) here here.