Cataract surgery involves removal of the cloudy lens and replacing it with an artificial lens. Not all cataract cases require surgery. However, surgery is the only effective treatment option in advanced cataract causing problems with routine activities such as driving, reading, cooking, watching television, and so on. Cataract surgery is done on an outpatient basis, usually under local anesthesia, and normally gives yields good results regarding improvement of vision. General anesthesia may occasionally be used and is the preferred option in children. It is a relatively safe surgery but occasional complications may include infection and bleeding. The risk of retinal detachment is slightly increased following cataract surgery.
Types of Cataract Surgery
First the affected lens is removed and replaced with a new lens. The three basic procedures for cataract lens removal are phacoemulsification (phaco), extracapsular surgery or intracapsular surgery. Phacoemulsification is the most commonly conducted and preferred procedure. Lens replacement may involve an acrylic, silicon or plastic implant. Sometimes, a follow-up procedure known as YAG laser capsulotomy may need to be done months or years after the original cataract surgery if cloudiness of the lens returns.
This is the most common procedure for cataract extraction. Using a microscope, a small incision is made in the surface of the eye, on the side of the cornea, through which a tiny probe is inserted into the eye. The probe emits sound waves or ultrasonic vibrations which are used to break up the opaque lens. The particles are then removed by suction. Phaco is also known as small-incision cataract surgery.
Advantages of Phaco Surgery
- Phaco is the most up to date method for cataract removal.
- It usually takes less than 30 minutes to perform.
- Mild sedation and anesthetic eye drops are sufficient for the procedure.
- The tiny incision on the eye does not require any stitches.
- An eye patch is not necessary after surgery.
Extracapsular Cataract Surgery or Extracapsular Cataract Extraction (ECCE)
In this method, a larger incision is made on the side of the cornea, through which the cloudy lens is removed as a whole. This procedure is usually undertaken in cases of advanced cataracts where the lens becomes very dense and phacoemulsification is therefore difficult.
Disadvantages of ECCE
- A larger incision is needed to take out the lens as a whole.
- Stitches are necessary to close the incision.
- A local anesthetic injection around the eye is necessary for the procedure.
- An eye patch is needed after surgery.
- Visual recovery may be slower.
Intracapsular Cataract Surgery
This older method of cataract removal, where the whole lens, together with its surrounding capsule, is removed through a larger surgical incision on the eye, is rarely used nowadays except in certain circumstances, such as a cataract caused by trauma to the eye.
Lens replacement follows any of the methods of lens removal. This is usually done by an intraocular lens (IOL), which is either a clear plastic, silicone, or acrylic lens implant that is placed inside the eye permanently. The IOL is folded in half during insertion so as to be able to pass through the small corneal incision. Once inside, it unfolds itself and fits into the space that was occupied by the previous lens. This lens requires no further care by the patient, and can neither be seen nor felt.
In the event of lens removal by phaco and ECCE procedures, the artificial lens is placed within the same capsule that had been occupied by the now removed natural lens. In intracapsular cataract surgery, since the capsule is removed along with the lens, the artificial lens is placed in front of the iris.
When IOL implant is not possible, either due to some eye disease or problems during surgery, soft contact lenses may be prescribed. Rarely, corrective eyeglasses with high magnification may be prescribed for lens replacement.
Types of Intraocular Lenses (IOL)
The various types of IOL that are available for implant after cataract surgery are :
- Monofocal lens. This type of lens is most commonly used in cataract surgery. These are fixed strength lenses set for one level of vision, usually distant vision. There is equal power in all regions of the lens. Good quality distant vision may be obtained by this type of lens, but it cannot correct astigmatism which is a type of refractive error caused by irregular curvature of the cornea. Other corrective lenses will also be required for near vision.
- Toric lens. This type of lens has more power in one particular region of the lens and can correct astigmatism as well as distant vision. However, corrective lenses will be required for near vision.
- Multifocal lens. These are highly advanced type of lenses that have different regions of varying strength, so that a person can see at all distances, such as near, intermediate, and far. It, however, cannot correct astigmatism. Multifocal lenses are not suitable for all patients since it can cause more glare than monofocal or toric lenses.
- Accommodating lens. This type of lens allows the eye to focus on both near and distant objects, similar to the natural human lens.
YAG Laser Capsulotomy
Sometimes, a secondary cataract develops many months or years after cataract surgery, due to cloudiness of the lens capsule enclosing the lens. This can be treated by yttrium-aluminum-garnet (YAG) laser capsulotomy, which is done as an outpatient procedure. A laser is used to make a tiny incision in the eye tissue behind the lens to allow light to pass through. The procedure is painless and does not usually cause any other eye problem.
Complications of Cataract Surgery
Although cataract surgery is generally a safe procedure, the complications that may occur are :
- Rise in intraocular pressure (high eye pressure)
- Increased risk of retinal detachment
- Damage to other parts of the eye, such as the cornea
- Tearing of the lens capsule
- Loss of vision
- After-cataract or secondary cataract. It is also known as posterior capsule opacification.