> Cataract surgery and types of lenses

Cataract surgery and types of lenses

During cataract surgery, the natural lens is sucked out and changed with an implanted intraocular lens. The eye cannot create a clear image without a lens.

The most modern method for cataract treatment using devices is called PHACOEMULSIFICATION.

The surgery is bloodless and doesn’t require stitches. It is done through a microscopic incision. It makes the natural lens turn into an emulsion. The whole intervention only takes 7-8 minutes, or even less.

Phacoemulsification is used with great levels of success in Medical Center Vereya thanks to the unique device used for it – Centurion. This device, which is from the latest generation of medical devices for cataract treatment, ensures stable ocular pressure during the procedure. Implanting the intraocular lens is done as easily as possible with the device’s computer system. Using this device for phacoemulsification means that there’s almost no friction or mechanical action on the eye and no side effects.

Types of intraocular lenses

An intraocular lens is an artificial lens which replaces the clouded natural ocular lense (cataract) and restores the vision of the eye. In history, the first intraocular lenses were hard. They are the most widespread lenses for surgeries done a decade or more ago, when cataract surgeries were done through a large incision without ultrasound. Recovery and discomfort in patients with hard intraocular lenses last for a longer time, while the risk from a large postoperative astigmatism is high.
With the developments in ocular surgery, the hard lenses have been taken over by the new generation of intraocular lenses – soft intraocular lenses.

The advantage of soft intraocular lenses is that they are implanted through a very small incision.

The variety of soft lenses is large, starting from the material they are made of, the technology, design, or different additional extras such as filters, additional focuses and others.
We can split them into
hydrophilic and hydrophobic according to the material they are made of. The differences are not large – maybe the most discussed difference is the higher occurrence of secondary cataracts when using hydrophilic lenses.

We can also split them into spheric and aspheric, when discussing the design of their optics. The advantage of aspheric lenses is the improved sensitivity to contrast and focus depth.

Intraocular lenses include filters that protect the retina from UV and other potentially dangerous light radiation. The ophthalmologist chooses the filters that can give the appropriate protection for the patient’s specific needs.

There are also some lenses with an additional filter, the so-called yellow lenses. The additional yellow filter is the closest to our natural lenses, as it is also yellow. Additionally, the yellow color filters the blue light that can be harmful to the cells of the macula. Those lenses are suitable for all ages and especially for young people with macular disease.

According to the technology of manufacturing there are 3 main types of intraocular lenses:

Monofocal – single focus lenses

This is the most common type of intraocular lenses which are in use for a few decades already. The traditional method of cataract surgery includes namely those monofocal – single focus lenses.

This type of lens is created to correct vision at close, medium or long distance
Most people use monofocal lenses to correct their long-distance vision and use glasses for reading and other activities performed at a short distance.
For cataracts in both eyes, it is possible to have a monofocal lens implanted in one eye for near vision and a monofocal lens implanted in the other eye for distance vision. This is known as “monovision.” Most people who choose monovision go through a short period of adjustment as the brain learns to see with the appropriate eye for each specific case. If you are considering refractive surgery as a permanent form of monovision, it may be best to try contact lenses before deciding.

This type of intraocular lens has a single focus point and is very suitable for correcting functional distance vision. This lens, however, doesn’t remove the need for using glasses for near vision, nor the necessity to use glasses or get further surgery for correcting astigmatism or another refractional anomaly.

MULTIFOCAL LENSES

These are a new type of intraocular lens that dramatically reduces or eliminates the need for glasses.

This type of intraocular lens is characterized by multiple focal zones or rings. Depending on where the incoming light is focused through the zones, the patient may be able to see both near and far objects clearly.
Their design allows certain muscles in the eye to move the lens back and forth, changing the focus, as with the natural lens, for clear vision at both distances.
The ability to read or perform other tasks without glasses varies from person to person, but for best results, it is recommended to have multifocal intraocular lenses inserted in both eyes.
It usually takes 6 to 12 weeks after surgery on the second eye for the brain to fully adapt and vision to improve.

For many people, these types of IOLs reduce, but do not eliminate, the need for glasses or contact lenses. For example, a person can read without glasses, but words are less clear than with glasses. Adaptation to these IOLs varies from person to person and may depend on the size of their pupils and other factors related to the health of their eyes. People with astigmatism can ask their eye doctor about toric IOLs and related procedures. Side effects, such as glare, halos around lights, or reduced visual acuity (contrast sensitivity), may occur, especially at night or in low light. Most people adjust and are not bothered by these effects, but those who frequently drive at night or need to focus on a close object for work may be more comfortable with monofocal IOLs.

TORIC LENSES

Astigmatism is an eye condition that impairs or blurs the ability to see both near and far objects. Special intraocular lenses are now available to correct astigmatism. They are specifically designed for patients with cataracts and corneal astigmatism. Patients with astigmatism are fitted with a special lens to compensate for this visual abnormality. It is called a toric lens and has an additional diopter per degree to focus light precisely on the retina. Toric lenses are monofocal intraocular lenses with built-in astigmatism correction. People who want to reduce (or possibly eliminate) the need for glasses may choose an additional procedure called “limbal relaxing incisions” (small incisions that allow the shape of the cornea to be round or more symmetrical). This procedure can be done at the time of cataract surgery, or separately.