MULTIFOCAL LENSES
Although cataract surgery is the process of cleaning the patient's cloudy lens (cataract) and replacing it with an artificial lens, with developing technologies, glasses can be removed completely after cataract surgery. It may also be possible to get rid of it partially. Artificial lenses placed inside the eye can be produced to correct the patient's refractive errors, thanks to today's technology. In fact, cataract surgery is recommended even for people who do not have cataracts after a certain age but do not want to use near or far glasses (clear lens extraction).
Refraction defects of the eye MYOPIA, HYPERMETROPIAand ASTIGMATISM. Precise measurements made before cataract surgery determine the number of the artificial lens to be placed in the eye. The aim of this is to get the number as close to zero as possible after surgery and to reduce the dependence on glasses or, if possible, to get rid of glasses. The patient's myopia and hypermetropia can be largely eliminated with a standard artificial lens placed in the eye according to precise measurements.
Standard lenses are monofocal and generally focus only on distance vision. These lenses do not have near vision capability. Although the patient sees distance clearly without glasses, his near vision is impaired and he must use glasses. This is a very natural consequence of the surgery. However, if the doctor does not provide full information before the surgery, it may be perceived as an incomplete intervention by the patient. However, at the end of this surgery, the patient became a healthy individual who did not use distance glasses. Every healthy individual starts using glasses from the age of 40-45. This is not a disease, it is a natural consequence of aging (like graying of hair). In summary, this is the result that can be achieved with standard single vision lenses.
However, thanks to the developing technologies in recent years, it is possible for the patient to see both near and far after cataract surgery without the need for glasses. There are different methods for this purpose. One of these is theMONOVISION technique. For this, the patient's dominant eye must undergo cataract surgery. While e is reset, the non-dominant eye is left slightly myopic (about 1.0-1.5D). In this way, the patient's dominant eye sees the distance clearly, while the non-dominant eye sees the near better. With this technique, the patient can perform most of his daily tasks (such as using a mobile phone, reading labels in the market) without the need for glasses. However, there will still be a need for glasses for a very clear and sharp vision both at a distance and near.
Another method is to place a MULTIFOCAL INTRAOCULAR LENS into the eye during cataract surgery. Multifocal intraocular lenses consist of intertwined rings of different refractivity that are focused at near, such as reading distance, at medium distance, such as computer distance, and at far distance, such as television distance. It is aimed to see all distances with the same lens. Cataract surgery technique is the same for multifocal lenses as it is for standard lenses. Only the type of lens placed inside the eye is different.
Which patients are suitable for multifocal lenses?
Although multifocal lenses seem very advantageous in theory, they may not be suitable for every patient. After surgery, halo formations around point lights (such as lamps), adaptation problems at intermediate distances, scattering and glare from lights such as sunlight or car headlights may occur. These complaints are largely temporary and are expected to regress within 3 to 6 months. In some patients, these complaints may be permanent. It has been reported that these complaints have been alleviated, especially the intermediate distance problems, with the trifocal lenses developed in recent years.
The most important issue regarding multifocal lenses is patient selection.
For multifocal lenses. Suitable patient criteria (patients who will get better results, although there is no definite indication):
- Those who have a strong desire to get rid of glasses
- Not too critical, more 'Carefree' people
- Those who do not expect very sharp near and far vision
- Those who are hyperopic or have very high myopic refractive errors
Patient criteria that may be considered unfavorable for multifocal lenses (patients who may be dissatisfied, although not certain)
- Patients who do not mind wearing glasses after surgery and who do not aim to get rid of glasses
- People who are very critical and have unrealistic expectations
- Very Those who expect sharp near and distance vision
- People who were previously myopic (these patients' near vision is usually extremely good and the quality of vision with a multifocal lens may be below their expectations)
- Those who have to drive at night, those who work in jobs that require a lot of effort with computers
- Patients with problems in the vision center (such as macular edema due to macular degeneration)
Cataract surgery with multifocal/trifocal lens is an extremely useful method with high patient satisfaction, if the appropriate patient is selected. However, patient selection is an important factor here.
Cataract and astigmatism
The transparent glass part of the eye called the cornea (like a watch glass) It is the most important refractive medium of the eye. It is spherical in structure(similar to the surface of a football). If one axis is flatter than the other, astigmatism occurs (similar to an American football). In fact, almost every eye has varying degrees of astigmatism, and no cornea is like a perfect sphere surface. It may be necessary to use glasses for astigmatism above a certain degree.
In a cataract patient with astigmatism above roughly 0.75D (diopters), standard intraocular lenses placed during surgery do not provide a complete astigmatism correction. A certain amount of astigmatism remains after the surgery. If the patient does not want to use distance glasses, the standard lens fitted may not satisfy the patient. For this, it is necessary to use an astigmatic lens called toric lens. These lenses are specially produced taking into account the patient's eye measurements. For this, the doctor must discuss all possible alternatives with the patient.
A cataract patient wearing toric lenses should know that he will be exempt from distance glasses, but will use near glasses.
The issue of astigmatism is also a concern for multifocal lenses. is a problem. If there is astigmatism over 0.75D, visual performance will not be good with flat multifocal lenses. Both multifocal and toric (with astigmatism) lenses should be preferred.
As can be seen, although it is possible to live without glasses after cataract surgery, there are many different conditions and methods for this. The patient must first have realistic expectations and know what he wants. The doctor also needs to inform his patient about the possible results and expectations.
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