CATARACT SURGERY & INTRAOCULAR LENSES

CATARACT SURGERY & INTRAOCULAR LENSES

Cataract surgery is all about removing the hazy/opaque lens in your eye, and in most of cases, replacing it with an artificial lens. In fact, it is among one of the most frequently and successfully carried out eye surgeries across the globe.

The Right Time to have Cataract Surgery:

When dealing with cataract removal, your doctor may ask you the following questions and accordingly decide to proceed with cataract surgery:

1. Is it difficult for you to carry out your daily or occupational activities?
2. Is your ability to drive or to work at night being affected?
3. Is reading or watching television becoming cumbersome for you?
4. Do you have issues in cooking, shopping, taking medications or climbing stairs?
5. Do you feel difficulty in seeing under bright lights?
6. Is your level of independence getting disturbed?
7. Is your problem manageable through alternative ways?

CATARACT SURGERY:

Cataract surgery is a microscopic surgery usually performed under local or topical anesthesia. The cloudy lens is removed by one of the surgical techniques and is replaced with a clear implant called an Intraocular Lens (IOL) to restore vision. In most cases, no stitches are needed and the eye heals quickly after surgery.

TYPES OF CATARACT SURGERY:

1. Phacoemulsification:

Also known as ‘Phaco’, it is the most common technique used for cataract removal nowadays. Usually, it takes no more than half an hour to remove cataract through phacoemulsification, and that too, requiring only local or topical anesthesia. This procedure requires a small surgical incision around the edge of the cornea, inserting a small ultrasonic probe into the opening to break up the cloudy lens into tiny fragments using sound waves and suction of broken down cataract fragments. Once the lens particles are removed, an IOL is implanted in the natural lens capsule.

2. Manual Small Incision cataract surgery:

Also called as MSICS or Manual Phaco. This is the cataract procedure used in case where phacoemulsification may not possible for various reasons. A slightly larger incision is required for this cataract removing technique, so that the cataract can be removed in one piece instead of being fragmented within the eye. Just like phacoemulsification, an artificial lens (IOL) is placed inside the capsular bag. No sutures are required to close the wound and it is a highly safe and reliable technique.

                  

3. Intracapsular cataract surgery

Though rarely used nowadays, this cataract removal technique may still be useful under certain circumstances. It comparatively requires a larger incision through which the entire lens with surrounding capsule is removed. Moreover, the IOL (intraocular lens) has to placed in a different location, as there is no capsular support.

4. Laser-assisted cataract surgery:

Also called LACS is a modern variation of the standard phaco cataract procedure. In laser cataract surgery, a number of steps that traditionally have been performed with a hand-held surgical instrument are instead done with a computer-controlled, high-speed laser for added precision. These steps include: making the initial incisions in the eye; creating an opening in the anterior capsule of the lens to gain access to the cataract; and fragmenting the cloudy lens prior to its removal from the eye.

TYPES OF INTRAOCULAR LENSES (IOL):

There are different types available, and your surgeon will help you understand which qualities you need and which lens material best suits your needs.Your surgeon will help you choose the ideal lens for you. The Eye surgeon is an expert on all available lenses and how their individual benefits pertain to each patient’s needs.

Types of IOL Materials -Materials continue to improve, becoming more pliable and bio-stable and evolving to address specific vision needs. The earliest IOLs were made with a thermal plastic, a material that improved dramatically over the years, but still had inherent restrictions for microsurgery. Today’s state-of-the-art acrylics offer better plasticity and stability and give surgeons superior control during microsurgery.

Polymethylmethacrylate (PMMA):

Once the standard for excellence, these lenses are not as pliable and conducive to micro procedures as newer materials. They are rigid and thus require a larger incision for insertion and are commonly used in MSICS surgery.

Silicone:

Also a popular choice that is giving way to advanced acrylics better suited to micro incisions. Certain bio-material advantages make silicone lenses the ideal choice for some patients.

Hydrophobic Acrylic:

Today’s most popular choice in part because it’s easy to fold and ideally suited for microsurgery. Most lens implants are performed with these advanced acrylics and have excellent success rate.

Hydrophilic Acrylic:

Similar to the Hydrophobic acrylic but with comparatively poorer bio-adhesion properties. However they are more economical.

FUNCTIONAL TYPES OF IOL:

Monofocal IOLs:

These lenses have been around longest and are still the most common IOLs. Though the quality of materials and designs continue to improve, the function of the lens remains constant. A mono-focal IOL has equal power in all regions and a single zone of clear focus, producing excellent vision from a determined distance. This gives excellent distance vision, but requires wear glasses for near-vision needs like reading. A smaller number of patients choose lenses that focus at a nearby point. This gives them excellent near vision, but they need to wear glasses to see distant objects.

Some patients choose distance vision for one lens and near vision for the other (called mono-vision) and rely on the brain’s natural tendency to compensate, often producing excellent vision near and far. Your surgeon will discuss this option and explain the key role your dominant eye plays in the decision.

Multifocal IOLs:

These special lenses continue to evolve with designs that offer a variety of regions with different power and several zones of clear vision within a single lens, allowing patients to see a continuous range of vision from long, intermediate and near distances. Results vary depending on each person’s eyes and IOL choice, but the vast majority of patients with multifocal lens implants achieve excellent levels of clarity and a general improvement over a broad range of vision. Rings and halos can occur, and your surgeon will discuss these concerns with you to make sure you understand all aspects of your options.

Accommodating IOLs:

These revolutionary IOLs flex like a human lens to achieve the continuous range of vision a person would have naturally. The lens accommodates itself to the shape of the eye, literally changing its shape and allowing itself to focus on both far and near objects. After implantation, patients typically function well without glasses for distance and intermediate viewing and often do not even require glasses for casual reading. Glasses are typically needed for fine print and micro tasks.

Toric IOLs:

The only lens type that can correct astigmatism, toric IOLs have different powers in different areas of the lens that align with the patient’s vision correction requirements. This alignment demands the lens be positioned in a precise configuration, placing greater emphasis on your surgeon’s expertise and surgical skill. They typically reduce the power of glasses at all distances and can minimize the need to wear glasses for distance vision.

Is cataract surgery serious?

All surgery involves some risk, so yes, it is serious. However, Cataract surgery is the most commonly performed type of surgery. Many cataract surgeons have several thousand procedures under their belt and chances of complications to occur are relatively rare. However some preexisting conditions in the eye or the body may predispose to certain specific complications.

What is a "secondary cataract"?

In a minority of cases (perhaps 20 to 30 percent), months or years after cataract surgery, the posterior portion of the lens capsule that is left inside the eye during surgery for safety reasons becomes hazy, causing vision to again become blurred.

This "secondary cataract" (also called posterior capsular opacification or PCO) usually can be easily treated with a less invasive procedure called a YAG laser capsulotomy. In most cases, this 15-minute procedure effectively restores clear vision.

THE NEED OF GLASSES AFTER A CATARACT SURGERY:

This would depend on the type of intraocular lenses (IOLs) used for you. The advanced intraocular lenses such as multifocal or accommodating IOLs greatly reduce dependency on glasses and in most cases even reading glasses can be avoided. Rarely does anyone have to wear thick eyeglasses after cataract surgery these days. In fact, premium Multifocal and accomodating IOLs can even eliminate your need for reading glasses after cataract surgery.

How much does cataract surgery cost?

It varies from one doctor to the next and it also depends on the type of procedure and intraocular lens you and your doctor decide is best for your needs.

What are the possible side effects of cataract surgery?

As with any surgery, pain, infection, swelling and bleeding are possible, but very few people experience serious complications. In most cases, complications or side effects from the procedure can be successfully managed with medication or a follow-up procedure. To reduce your risk for problems after cataract surgery, be sure to follow the instructions your surgeon gives you and report any unusual symptoms immediately.

Please feel free to ask for any query pertaining to this blog or any other eye related topics.

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Thank You.

* The author is a Consultant Ophthalmologist,Eye Surgeon and Medical Director of Prem Jyoti Eye Care and Hospital, Bhilad(India)