Op. Dr. Hulya Bolu | Intraocular Lenses

Intraocular Lenses

There is an undeniable relationship between our genetic heritage, our advancing age, and the habits we have while continuing our lives, and our eye health. Sometimes, our genetic heritage and secondary diseases we have at a young age, sometimes environmental factors we are exposed to in middle age, and mostly with the effect of aging, regression begins in our eye health.


With the effect of developing medical technologies in the treatment of diseases that impair our eye health, we can achieve very successful results. We can increase the clarity of vision of our patients and increase their comfort of life.


One of the methods we apply to increase the comfort of our patients and to eliminate vision problems is intraocular lenses. Intraocular lenses should not be confused with contact lenses. Unlike contact lenses, intraocular lenses replace the natural lens in the eye. For this reason, intraocular lenses are used in the treatment of refractive disorders in patients who have conditions that prevent the application of Excimer laser therapy, especially cataracts.


What are Intraocular Lenses? Briefly Known About Intraocular Lenses


Intraocular artificial lens are artificial lenses produced by using special technologies to replace the natural lens in the eye in order to eliminate the visual defects caused by the structural and functional deterioration of the natural lens in the eye.


Intraocular lenses can be used in an operation called clear lens replacement, both for replacing the natural lens of the eye that has been impaired during cataract surgery and for the treatment of refractive disorders in the eye.


As a result of the differentiation of the needs of the patients, the intraocular lens technology has also differentiated and diversified. Therefore, intraocular lenses have evolved over time and are equipped with features that will increase the comfort of patients.


Today, a wide variety of intraocular lenses with different functions are used. Determining which intraocular lenses are suitable for which patient is a matter that requires experience and accurate evaluation of comprehensive examination results.


The success of the intraocular lens implantation operation depends on multiple factors. Before the intraocular lens is placed, many different factors should be evaluated simultaneously, including the age of the person, eye tissue, general health status, needs, social status, realistic expectations and even the occupational group to which he is involved. The lens used MUST meet quality standards.


In the success of intraocular lens exchange, the experience of the doctor and technological equipment should be taken into account in order to carry out detailed examinations before the operation. If all the examinations are not performed before the intraocular lens surgery, it will not be possible to determine the correct lens to be used by the patient and to increase the patient’s comfort. It should not be forgotten that the technique preferred during intraocular lens surgery is also very important for the success of the post-operative process. Today, the lens performance is maximized as the lens can be perfectly placed on the eye with Femtosecond laser technology. Moreover, since all procedures are performed with laser technology under computer control, the risk of complications is minimized.


What are the Types of Intraocular Lenses?


The materials and technologies used in the production of intraocular lenses change and develop over time. While the lenses produced with the technology of the past years are replaced by new technologies, new intraocular lenses are being introduced to increase our comfort day by day.


In this part of my article, I will provide information about the most commonly used intraocular lenses, namely, single-focal (monofocal), toric, multifocal (multifocal), phakic and Add-on lenses.


  1. Monofocal Lenses


Monofocal lenses can be briefly defined as fixed focus artificial intraocular lenses. Single vision lenses are designed to see only far or near. Monofocal lenses, also known as 1st generation intraocular lenses, have the title of being the most common and most used artificial intraocular lenses today.


With the development of technology, single vision lenses have also evolved in their own evolutionary story. Although the quality of materials and designs of single vision lenses has improved, the function of the lens has not changed.


Unlike new generation smart lenses, monofocal lenses do not completely eliminate the need for patients to wear glasses. Because they are single-focused, they usually only allow the patient to recover from distant vision defects. The patient can continue to use glasses for near and intermediate vision; which is the disadvantage of monofocal lenses.


  1. Toric Lenses


Before toric lenses, I would like to give a brief information about astigmatism.


Astigmatism, which causes decreased night vision, headache, blurred vision and eye fatigue, is an eye disease that occurs when the cornea or intraocular lens does not have the ideal shape. In order for us to see clearly and healthily, all layers of our eyes must be in ideal shapes; otherwise, our eyes lose their ability to focus the light on the retina and vision problems occur.


In a healthy eye without astigmatism, both the cornea and the intraocular lens have a smooth surface and light can be focused on the retina. However, if irregularities occur in the cornea or intraocular lens, the image also loses its clarity. Here, lenses placed inside the eye to eliminate astigmatism and naturally both near and far vision are called “toric intraocular lenses”.


Toric intraocular lens treatment, like all other types of intraocular lenses, first requires the removal of the natural intraocular lens. At this point, cataract surgery comes into play with FemtoSaniye, which I mentioned in the introduction part of our article.


“If a person has astigmatism in their own eye, toric lenses should be used.”


  1. Multifocal Intraocular Lenses


Multifocal lenses have been developed because monofocal lenses cannot provide the opportunity to get rid of glasses and contact lenses at all distances. Unlike monofocal lenses, multifocal lenses have at least two or a single multifunctional focus, depending on the type of multifocal lens, rather than a single focus.


Multifocal intraocular lenses have circle that allow images at various distances to be focused on the retina. Initially, it may take time for patients to get used to multifocal lenses, but it is possible to achieve great comfort with multifocal lenses over time. Due to their design, multifocal eyepieces are permanent for a lifetime, allowing clear vision of both close, intermediate and long distances. Once they are put on the eye, there is no progression in the eye numbers or cataract formation in the eye lens.

There are many different types of multifocal intraocular lenses:


Bifocal (Bifocal Lenses): They are the next generation intraocular lenses. Although they are called multifocal lenses, they should be defined as “bifocal lenses” in essence. Bifocal lenses provide a clear image at both near and far distances. Although bifocal intraocular lenses are mostly applied to patients with cataract problems, they are also recommended for patients with high number of myopia and hyperopia who are not suitable for LASIK.


Trifocal (Smart Lenses): Unlike bifocal lenses, trifocal lenses have three focal points. Therefore, patients can have clear vision at both near, intermediate and far distances. In patients who do not want to use glasses or lenses after cataract surgery, the existing eye diseases of the patients should be evaluated before smart lenses are placed.


Accommodative: Although accommodative lenses have a single focal point, unlike multifocal lenses, their single focus is multifunctional. This type of intraocular lens, which works by taking advantage of the functions of the ciliary muscle after the cataract eye lens is removed, makes it possible for patients to have a comfortable vision.


EDOF (Intraocular Lenses with Increased Depth of Focus): EDOF intraocular lenses, developed to reduce light scattering and circle formation around lights at the night, provide uninterrupted vision at long and medium distances. Compared to trifocal intraocular lenses, EDOF lenses with low near vision performance are considered to have better performance at medium and long distances.


  1. Phakic Intraocular Lenses


Intraocular lenses made of plastic or silicone, which are permanently implanted in the eye in order to reduce the need for glasses or contact lenses and provide a permanent solution to refractive disorders in the eye, are called phakic lenses. Phakic lenses can be applied to patients with refractive disorders such as myopia, astigmatism and hyperopia, but whose corneal thickness is not sufficient or whose degrees are too high to apply LASIK treatment. Different from other intraocular lenses, phakic intraocular lenses can be placed in front of or behind the iris layer. These features distinguish them from monofocal, bifocal, toric and trifocal intraocular lenses. The phakic intraocular lenses, which can be preferred in cases where the person does not have cataracts, are produced in a way that will not damage the natural lens in the eye.


  1. Add-on / Sulcoflex Secondary Intraocular Lenses


Artificial intraocular lenses placed on the old lens are defined as “add-on lenses” in order to provide clearer vision at near, intermediate and far distances for patients who have had an artificial eye lens because they had cataract surgery in the past. In order for add-on lenses to be preferred, patients should be examined in detail. The suitability of the patient is very important in Add-on lenses, as in all other intraocular lenses.


FAQ About Intraocular Lenses

What is Intraocular Lens?

If the function of the natural intraocular lens is impaired, artificial intraocular lens therapy can be applied. Artificial intraocular lenses are transparent and elastic like natural eye lenses. They can be produced in line with different needs and have different properties.

In Which Situations Are Intraocular Lenses Used?

The most common reason for using intraocular lenses is cataract disease. Since the intraocular lenses lose their transparency in cataract patients, vision loss is compensated by intraocular lenses. However, cataract should not be considered as the only eye disease in which intraocular lenses are used. Today, intraocular lenses can be preferred in patients to eliminate refractive disorders, to treat astigmatism or to eliminate the need to wear glasses after cataract surgery in the past years.

Who is Intraocular Lens Applied to?

The answer to this question may vary depending on the age of the patients, their expectations, their corneal thickness, their general health, whether they have had previous eye surgeries, whether they have eye diseases and the surgeons’ evaluations. But still, to put it in the most general way who are;


  • Decreased vision quality due to cataract disease,
  • Over 40 years of age with refractive errors,
  • young but whose refractive errors are not suitable for laser eye surgery
  • I would say that intraocular lenses can be placed.

How is Intraocular Lens Surgery Performed?

All intraocular lenses that require removal of the natural intraocular lens for application can be made within the same procedure. Intraocular lens surgery and cataract surgery are performed in the same way. Today, the most advanced technique in cataract surgery is cataract surgery with FemtoSaniye. During this technique, a controlled opening is created in front of the membrane surrounding the natural lens with the laser to access the lens of the eye. The natural lens of the eye is taken the pieces and absorbed. Then, artificial eye lenses are placed into the eye with the help of a special injector. Since the eye is anesthetized with eye drops during the operation, it is not possible for the patients to feel any pain. After the lens is placed, an antibiotic drug is given into the eye and no stitches are placed.

Although this procedure is generally applied, different techniques from cataract surgery are used when inserting a phakic intraocular lens or Add-on. There is no need to remove the existing intraocular lens in order to attach both lenses. The phakic intraocular lens is placed in front of or behind the iris with the patient’s own natural lens in place; The add-on is attached to the artificial lens that was put into the eye in the past.

How is the Intraocular Lens Type Decided?

Many factors must be evaluated simultaneously in the process of deciding on the type of intraocular lens. It is evaluated together with factors such as the age of the patients, their vision problems, corneal thickness, eye numbers, whether they want to use glasses or contact lenses, and the results of the surgeons’ evaluations.

What are the Risks of Intraocular Lens Surgery?

Intraocular lens surgery should be considered as a process that requires a lot of experience. It requires not only the experience of the surgeon, but also the full performance of the examinations and the correct choice of patient-specific intraocular lenses. The quality of the selected intraocular lenses is also one of the issues to be considered at this stage.

I can say that intraocular lens surgery performed by experienced surgeons using advanced technologies is quite safe.