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Types of Lenses Used in Cataract Surgery

Types of Lenses Used in Cataract Surgery

Cataract is an eye disease that occurs when the eye lens loses its transparency and is common with age. The only treatment method for cataracts is surgery. During this surgery, the natural eye lens, which has lost its transparency, is removed and replaced with an artificial intraocular lens (IOL). Today, the optical correction properties (reducing the need for glasses) of artificial lenses have improved. There are several types with these properties. In the days before lenses, patients who underwent cataract surgery had to wear high-numbered glasses, averaging 10-12 diopters (prescription).

The natural eye lens is approximately 20-22 diopters (prescription) in all people. The prescription number to be fitted is calculated using special optical measurements and formulas written on the devices.

1) MONOFOCAL LENS

The most commonly used are monofocal lenses.

As the name suggests, monofocal lenses provide clarity at only one focal length.

They are mostly focused on distances (e.g., driving, watching television), and the need for glasses at a distance is almost minimized. However, the patient cannot see at intermediate (60cm) and near (40cm) distances and needs to wear reading glasses (e.g., using a computer, seeing car dashboards, reading books, using a phone).

In some patients, one eye can be adjusted to see only at a distance and the other eye to see slightly near. This is called monovision. Although it reduces the need for reading glasses in daily life, reading glasses are still needed in certain situations (e.g., reading books). However, not every patient may adapt to this situation. Correction may require a second surgery, such as replacing the lens with an Excimer Laser or placing a low-number additional lens on the existing lens. Therefore, it is not often preferred. Rarely, it can be determined as focused on near distances (e.g., reading a book, using a phone).

The patient needs to wear distance glasses. (e.g., driving, watching television) Also, they cannot correct ASTIGMATISM. Therefore, the patient needs to wear glasses for both distance and near vision.

Disadvantages in Daily Life

If adjusted for distance vision; you cannot see the labels while shopping at the market, you need to check your watch briefly, you need to look at your phone, you cannot see the screen, you need to wear reading glasses. You cannot see the cockpit while driving. You may need to change your distance and near glasses frequently during daily activities. If adjusted for near vision; you may need to change your distance and near glasses frequently because you cannot see clearly what is coming from in front of you while working at your desk in the office, and therefore you cannot see distant objects clearly during daily activities.

Reasons for Choosing Monofocal Lenses:

They are more economical than others.

They are suitable for patients who are not bothered by wearing glasses.

Even if glasses are necessary, the image quality is generally very clear.

Intraocular reflections (halos, glare) are less than with multifocal lenses.

They are a safer choice for patients with unsuitable eye structures (such as those with corneal structure unsuitable for multifocal lenses, corneal disease, retinal disease, diabetic retinopathy, macular degeneration, or severe glaucoma).

2-TORIC (ASTIGMATE CORRECTING) LENSES

These lenses correct astigmatism while minimizing the need for glasses at a single focal length (far or near). Like monofocal lenses, they only provide clarity at a single focal length. Because they correct astigmatism, they improve visual comfort and clarity more than monofocal lenses.

They are mostly focused on distance vision (e.g., driving, watching television), minimizing the need for glasses at distances. Since they correct astigmatism, glasses are largely unnecessary for distance vision. They provide better visual comfort and clarity for patients with high astigmatism. However, if the patient cannot see at intermediate (60cm) and near (40cm) distances, they will need reading glasses (e.g., using a computer, seeing car dashboards, reading books, using a phone).

As with monofocal lenses that do not correct astigmatism, some patients can have one eye adjusted to see only distant objects while the other sees slightly closer. This is called monovision. While it reduces the need for reading glasses in daily life, they will still need to wear them in certain situations (e.g., when reading a book). However, not every patient can adapt to this. Correction may require a second surgery, such as replacing the lens with an excimer laser or placing a lower-powered additional lens on top of the existing one. Therefore, it is not often preferred.

Rarely, it may be determined as focusing on near distances (e.g., reading a book, using a phone). The patient needs to wear distance glasses. (e.g., driving, watching television)

The disadvantages in daily life are the same as with monofocal lenses.

Reasons for Choosing Toric (astigmatism correcting) Lenses

They are more economical than multifocal lenses.

They are suitable for patients with astigmatism, especially high astigmatism.

They are suitable for patients who are not bothered by wearing glasses.

Even if glasses are necessary, the image quality is generally very clear.

Intraocular reflections (halos, glare) are less than with multifocal lenses.

They are a safer choice for patients with unsuitable eye structures (such as those with corneal structure unsuitable for multifocal lenses, corneal disease, retinal disease, diabetic retinopathy, macular degeneration, or severe glaucoma).

3-MULTIFOCAL LENSES

There are two types: Trifocal and EDOF.

A-) Trifocal (Three-Focal) Lenses

These lenses are designed to provide clarity at three different distances: far, intermediate, and near. Thanks to the prismatic rings on them, they project images simultaneously from 40cm (near reading distance), 60cm (distances such as computer screens, car cockpits), and far distances to the sharp vision distance on the retina of the eye. Your brain chooses whichever distance you are looking at. Thus, the need for glasses in your life is minimized at all three distances. They also have astigmatism correction features. For example:

Far distance: driving, watching TV

Intermediate distance: computer, kitchen counter

Near distance: reading a book, using a phone, etc.

Due to the prismatic rings on them;

They cause light reflections (halo, glare). It's hardly noticeable during the day, but at night, because the pupil dilates in the dark, streetlights, car headlights, and starbursts appear as light. Because the prismatic rings on the lenses absorb about 7-8% of the incoming light, the amount of light entering the eye decreases.

So, if there's 100 watts of light outside, only 92-93 watts will enter the eye.

This creates a need for more illumination at closer distances. Reading becomes difficult in dim light.

The effect at a distance, which occurs at very long distances, is that the color tones of objects become faded. Difficulty is felt at a distance.

However, the brain adapts to these situations in most patients. It ignores these effects, like not feeling your watch or ring. They either become imperceptible or their perception is reduced.

Furthermore, in new generation Trifocal (Three-Focal) lenses, the number of prismatic rings has been reduced, significantly minimizing these negative effects.

There is a high satisfaction rate among patients who lead active lives.

It is also used to minimize the need for glasses in patients over 50 who do not have cataracts and do not want to wear glasses.

Trifocal (Three-Focal) Lenses are not suitable for every patient.

The corneal structure must be suitable for multifocal lenses. This suitability can be determined with advanced diagnostic equipment.

There should be no corneal disease.

There should be no retinal disease (such as diabetic retinopathy, macular degeneration).

There should be no severe glaucoma.

They are not preferred in long-distance drivers and patients who are very detail-oriented.

Appropriate patient selection and correct surgical planning are essential.

B-) EDOF (Extended Depth of Focus) – Wide Depth of Focus Lenses

EDOF lenses provide clear vision at intermediate and far distances by creating a wide depth of focus rather than a single focus. They do this with a higher power than the distance vision of the lens placed in the center of the lens. Since the transition between the two powers is smooth, the patient cannot feel the difference. They also have astigmatism correction features.

New generation models also support near reading distance. For example:

Far distance: driving, watching TV

Intermediate distance: computer, kitchen counter

Near distance: reading books, using the phone, etc. (Lower power glasses may be needed for near reading) This need has decreased in new generation models.

Advantages:

Light reflections (halo, glare) are less than with trifocal (three-focus) lenses.

Since they do not have prismatic rings, there is almost no reduction in the amount of light entering the eye. Therefore, night vision is more comfortable, there is no glare from lights, and the loss of tone and blurriness in distant objects is much less. It is ideal especially for long-distance drivers and individuals who work at medium distances, such as computer users.

Patients should be considered when evaluating patients with intensive reading habits.

Again, appropriate patient selection and correct surgical planning are essential.

As with trifocal (three-focus) lenses:

There is a high satisfaction rate in patients who lead active lives.

If the patient is not satisfied, multifocal (trifocal and EDOF) lenses can be removed and replaced with monofocal or toric (which also corrects astigmatism) lenses. However, this surgical procedure carries more risk than the surgery performed to implant the lens.

It is also used to minimize the need for glasses in patients over 50 who do not have cataracts and do not want to wear glasses.

4-ADD-ON LENSES

“A Chance to Eliminate the Need for Glasses for Patients Who Have Previously Undergone Cataract Surgery, Have Single-Focus Lenses Implanted, and Use Glasses”

Add-On Lens Application (Secondary Lens Implantation)

Many patients who have undergone cataract surgery have traditionally had single-focus (monofocal) lenses implanted. These lenses usually only correct distance vision, so patients may still need to wear glasses for near tasks (reading, writing, using a phone, etc.) after surgery. In fact, some patients may still have insufficient or excessive eyeglass prescription and astigmatism that need to be corrected for distance vision. (This situation is usually due to errors in the devices that calculate the lens prescription or the existing lens not being able to fully meet the required lens prescription or astigmatism for the patient's eye.)

However, thanks to the lens technologies that have developed in recent years, it has become possible to minimize the need for glasses for these patients as well. One of these innovations, the Add-On lens application, offers patients who have previously undergone cataract surgery and wear glasses with single-focus lenses the opportunity to minimize their need for glasses.

What is an Add-On Lens?

An add-on lens is a secondary artificial lens placed behind the pupil, on top of the primary (original) intraocular lens that was previously implanted in the eye. The Turkish meaning of the word "add-on" can be roughly translated as "placed on/added to". An add-on lens can address issues that a monofocal lens implanted during previous cataract surgery cannot:

Minimize or eliminate the need for reading glasses

Correct any missing or excessive distance vision

Correct any remaining astigmatism

Correct all of the above problems simultaneously in a single procedure

Also, with a SPECIAL model, it can improve near vision and reading in patients with dry type macular degeneration.

IN CONCLUSION:

They can drive a vehicle at a long distance.

They can see a computer screen at a medium distance.

The need for glasses can be minimized or eliminated when reading books or using a phone at close range.

If you have dry type macular degeneration, your near vision may improve slightly.

By solving the above-mentioned glasses requirement problems, it improves your quality of life by almost eliminating the need for glasses.

What is the application process like?

 Examination and preliminary assessment.

An examination and some tests are performed to thoroughly examine the structure of the front part of the eye, the health of the cornea and retina, and the position and condition of the existing lens.

Certain criteria are necessary for its application. If your eye meets these criteria, it can be applied surgically. Add-on lenses can be planned and manufactured specifically for each individual. Who is not suitable for Add-on lenses?

Patients with unstable intraocular lenses

Those with very shallow anterior chambers

Those with a low number of endothelial cells

Individuals with unsuitable corneal health and structure

Individuals with severe retinal diseases (such as diabetic retinopathy, previous serious retinal surgery)

Individuals with severe glaucoma

Individuals who have previously had intraocular inflammation (such as uveitis)

The surgical procedure is short

Intraocular surgery, unless the patient has a special condition, is usually completed with local anesthesia, without the need for general anesthesia, and is generally a short procedure (average 10-15 minutes). This time period may vary depending on the patient's eye structure and any additional procedures required during the surgery. The add-on lens is placed over the previously implanted lens after a small incision is made in the eye, according to the conditions, and the surgery is complete. Since it is only a lens implantation procedure, it carries significantly fewer risks than a standard cataract surgery. After the surgery, the patient is kept under observation for a while, and after ensuring there are no complications, they are sent home. Protective eyewear is used on the day of the surgery. An eye bandage may also be applied depending on the patient's condition. Antibiotic and corticosteroid eye drops and artificial tears are given. These will be used according to your doctor's recommendations.

Improvement
Because the surgery is short and requires fewer procedures than a standard cataract surgery, recovery is usually rapid, and patients can return to their daily lives within a few days. Recovery time may vary depending on the patient's overall health, age, and the type of surgery performed. In the first 24 hours, there may be a slight discomfort or blurring in the eye, but this is usually temporary and resolves on its own. Most patients notice a significant improvement in vision within the first week after surgery. Full recovery and ultimate visual clarity may take up to several weeks.

Routine Checks

Follow-up appointments are scheduled for day 1, week 3, and month 3 after surgery, but your doctor may adjust the frequency and timing of check-ups if deemed appropriate.

Rare but possible problems after intraocular lens surgery.

Remaining refractive error: If a refractive error persists, and there are no contraindications, it can be removed with an Excimer Laser.

Corneal edema: This can develop if the innermost layer of the cornea is damaged during surgery. It will usually resolve with eye drops prescribed by your doctor.

High intraocular pressure (glaucoma): This is a condition that can occur after intraocular surgeries. It causes eye pain. It will usually resolve with eye drops prescribed by your doctor. Very rarely, a second intervention may be required.

Eye infection: Infections can occur after intraocular surgeries, although very rare. This is a serious condition requiring early intervention. It can be treated with eye drops and medication.

Bleeding: Bleeding can occur in the blood vessels of the iris tissue. It is usually easily controlled. It can be treated with eye drops and medication.

Retinal tear: This is a rare condition that can occur after intraocular surgeries. It should be treated by a retinal specialist.

Also: Add-on lenses are removable lenses. The surgery is reversible.

*Since every surgery carries its own risks, the risks listed above, although rare, necessitate informing the patient about them.

 *HOWEVER, IT ENDS WITHOUT PROBLEMS IN A HIGH COUNT.

Success Rates and Patient Satisfaction

Current studies and clinical observations show that Add-On lens applications:

Increase the rate of glasses-free living,

Improve visual quality,

Significantly increase patient satisfaction.

5- Phakic IOL (Intraocular Lens)

What is Phakic IOL (Intraocular Lens) Treatment?

If refractive errors such as hyperopia, myopia, and astigmatism are too high to be corrected with Excimer Laser (LASIK or No-touch) treatment, or if the corneal structure/thickness is insufficient for LASIK treatment, phakic intraocular lens implantation can be an alternative method.

It is a good option, especially for patients with refractive errors above approximately 8-10 diopters of myopia, 5-6 diopters of hyperopia, and astigmatism, to correct the need for glasses.

However, it can also be applied to patients whose need for glasses is lower than the above-mentioned numbers but whose corneal structure/thickness is insufficient for Excimer Laser treatment. It can also be applied to suitable keratoconus patients. However, the aim here is not to completely correct the need for glasses, but to minimize it to the extent that will improve the patient's quality of life.

The Fundamental Principle of Fakik IOL

The patient's own natural lens is left in place without surgical intervention and/or removal. Instead, in the commonly used phakic IOL model, a thin, transparent lens is placed behind the pupil, the colored part of the eye – the iris – and just in front of the natural lens. In a less commonly used model, the lens is attached to the iris, in front of the pupil, with clamps.

Advantages

The natural lens remains in place. It can be removed if necessary.

It may be more effective than laser for high prescriptions.

It provides good quality vision.

Problems that can occur after laser treatment, such as dry eye syndrome, are less common.

What is the application process like?

Examination and Preliminary Assessment

An examination and some tests are performed to thoroughly examine the eyeglass prescription, the structure of the front of the eye, the health of the cornea and retina, and the condition of the natural lens. Certain criteria are necessary for application. Individuals over 18 years of age (usually over 20 years of age are preferred) and whose eye prescription has been stable for the last year.

Intraocular structure (intraocular depth - anterior chamber, angle between the cornea and iris, number of endothelial cells, etc.)

Those suitable for Phakic IOL

If your eye meets these criteria, Phakic IOL treatment can be performed surgically. Phakic IOL can be planned and produced specifically for each individual.

Who is not suitable for Phakic IOL?

Individuals with cataracts

Individuals with a very shallow anterior chamber of the eye

Individuals with a narrow angle between the cornea and iris

Individuals with insufficient corneal endothelial cell count

Individuals with unsuitable corneal health and structure

Individuals with severe retinal diseases (such as diabetic retinopathy, previous serious retinal surgery)

Individuals with severe glaucoma

Individuals who have previously had intraocular inflammation (such as uveitis)

The Surgical Procedure is Short

Since intraocular surgery is performed in an area as narrow as 3mm and without touching the natural intraocular lens, it is usually completed with a short procedure (average 10-15 minutes) under general anesthesia. Each eye is operated on separately at different times. This time may vary depending on the patient's eye structure and some additional procedures required during the surgery. In phakic IOL surgery, after a small incision is made in the eye, it is placed on top of the natural intraocular lens without touching it, according to the conditions, and the surgery is finished. Since it only involves the implantation of a lens, this surgery carries fewer risks than a standard cataract surgery. After the surgery, the patient is kept under observation for a while, and after ensuring there are no complications, they are sent home. Protective eyewear is used on the day of the surgery. Depending on the patient's condition, an eye bandage may also be applied. Antibiotic and corticosteroid eye drops, as well as artificial tears, are given. These should be used as directed by your doctor.

Improvement
Because the surgery is short, requires fewer procedures than a standard cataract surgery, and is performed without touching the natural intraocular lens, recovery is usually rapid, and patients can return to their daily lives within a few days. Recovery time may vary depending on the patient's general health and the course of the surgery.

In the first 24 hours, there may be a slight discomfort or blurring in the eye, but this is usually temporary and resolves on its own. Most patients notice a significant improvement in vision within the first week after surgery. It may take up to several weeks to achieve full recovery and ultimate visual clarity.

Routine check-ups are on day 1, week 3, and month 3 post-operatively, but your doctor may change the frequency and timing of check-ups if deemed appropriate.

Rare but possible problems after intraocular lens surgery.

Remaining refractive error: If a refractive error remains, it can be removed with Excimer Laser if there are no contraindications.

Cornea edema: This can develop if the innermost layer of the cornea is damaged during surgery. It will usually resolve with drops prescribed by your doctor.

High intraocular pressure (glaucoma): This is a condition that can occur after intraocular surgeries. It causes eye pain. It will usually resolve with drops prescribed by your doctor. Very rarely, it may be necessary to remove the phakic IOL.

Eye infection: Infections can occur after intraocular surgeries, although very rare. It is a serious condition and requires early intervention. It can be treated with drops and medication.

Bleeding: Bleeding may occur in the vessels of the iris tissue. It can usually be easily controlled. It can be treated with drops and medication.

Retinal tear: This is a condition that can rarely occur after intraocular surgeries. It should be treated by a retinal specialist.

Cataract may develop: By removing the phakic IOL and performing cataract surgery, a suitable lens can be implanted, reducing or almost eliminating your need for glasses.

Halos and flashes: These are quite rare. They become almost imperceptible within about 3 months.

Also: The phakic IOL is a removable lens. The surgery is reversible.

*Since every surgery carries its own risks, the risks listed above, although rare, must be explained to the patient.

 *HOWEVER, IT ENDS WITHOUT PROBLEMS IN A HIGH COUNTRY.

Success Rates and Patient Satisfaction

Current studies and clinical observations show that phakic IOL implants:

Increase the rate of glasses-free living

Improve visual quality

Significantly increase patient satisfaction

Conclusion

Your second chance could be a phakic IOL lens.

Conclusion

Phakic IOL treatment is an effective and safe method that offers quality and stable vision, especially in high-grade refractive errors. However, it is not suitable for every patient.

“The results of any surgical or interventional procedure can vary from person to person. It is recommended that you get a detailed consultation with your doctor before the procedure.”

Publication Date: 20.01.2026

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