What is cataract (Cat)?It is a clouding of the normally clear lens of the eye. A cloudy lens prevents light from focusing sharply on the retina. It is not:
- a film over the eye;
- caused by overusing the eyes;
- spread from one eye to the other;
- a cause of irreversible blindness.
When must a Cat be removed?
A cataract does not have to be removed just because it is there. Cat surgery should be considered when it causes enough vision loss to interfere with daily activities, such as work, driving, hobbies, reading, or watching television. It is a misconception that a Cat needs to be “ripe” before it can be removed. Surgery is performed when a person’s visual needs require it. You and your ophthalmologist can decide together when surgery is appropriate.
Causes and Symptoms
There are many types of cataracts. Most of them are caused by a change in the chemical composition of the lens, resulting in a loss of lens transparency. These changes can be caused by aging, eye injuries, certain diseases and conditions of the eye and body, certain medications (especially steroids), and hereditary or birth defects. If and when the normal process of aging causes the lens to harden and turn cloudy, they are called senile cataracts. These are the most common type. They can occur as early as age 40. Children are not impervious to cataracts either, and when they appear in children, they are sometimes inherited. They can also be caused by an infection or inflammation during pregnancy which affects the unborn baby. This latter type of Cat is called congenital, meaning present at birth. Eye injuries can cause cataracts in people of any age. A hard blow, puncture, cut, chemical burn, or rarely, extreme heat can damage the lens and result in what is called a traumatic Cat. Depending on the size and location of the cloudy areas in a lens, a person may or may not be aware that a Cat is developing. If it is located on the outer edge of the lens, no change in vision may be noticed. If the cloudiness is located near the center of the lens, it usually interferes with clear sight. Common symptoms experienced with developing cataracts include blurred or double vision, sensitivity to light and glare which make driving difficult, less vivid perception of color, and frequent eyeglass prescription changes. As the Cat grows worse, stronger glasses will no longer improve sight. The pupil, which normally appears black, may undergo noticeable color changes and appear to be yellowish or white.
What are the treatment options?
Surgery is the only way to remove cataracts. If the symptoms are not affecting your normal activities, surgery may not be needed. Sometimes a simple change in your eyeglass prescription can delay the need for surgery.
How is Cat surgery performed?
The surgery is usually an outpatient procedure, performed under local or topical anesthesia. The cloudy lens is broken up and removed through a tiny incision at the edge of the cornea and an intraocular lens (IOL) is inserted to replace your eye’s natural lens.
Most patients go home from the hospital on the day of surgery, although some prefer an overnight stay.
What type of anaesthesia is used in Cat surgery?
The most common type of used anaesthesia is local anaesthesia. Local anaesthesia can be administered with an injection around the eye or by eye drops. Although extremely rare, the risks of anaesthesia administered by injection include haemorrhage or injury to the eye. Occasionally general anaesthesia is preferred for Cat surgery. The risks of general anaesthesia should be discussed with your anaesthetist.
What can I expect after Cat surgery?
Most surgical procedures are performed without complications and result in immediate improvement in vision. The bandage will be removed from the eye on the day after surgery. Eye drops will be needed for several weeks. Occasionally, tablets are needed if the eye pressure is high. The amount of physical activity allowed after surgery is variable. Your surgeon will tell you about showering and activity restrictions. The eye may be slightly red and tender, but severe pain is not to be expected. If you develop increased pain, redness, or discharge after surgery, or if your vision worsens, then contact your ophthalmologist immediately. Depending on the preference of your surgeon, stitches may need to be removed from the eye several weeks after surgery. Visual recovery is variable. Some patients see very well a few days after surgery, while for others improvement may take several weeks. A change in glasses is generally made several weeks after surgery. Most patients still need glasses after the surgery for some activities, particularly reading.
You will apply eyedrops for several weeks following surgery to reduce the possibility of infection and/or inflammation in the eye.
You may need eyeglasses to obtain your clearest vision following surgery.
Will the Cat grow back?
It does not grow back after it is removed, but sometimes the vision gradually becomes blurred after Cat surgery, similar to the way the vision was blurred by the Cat. This blurring is caused by a condition related to the Cat. The natural lens of the eye has a cellophane-like coating called the capsule. The most common method of removing a Cat leaves part of the capsule intact. The capsule provides a natural barrier between the front and back parts of the eye and helps to support the intraocular lens implant. The capsule is normally clear, like a sheet of stretched cellophane, but with the passage of time it may become cloudy or wrinkled. When this happens the vision becomes blurred. This condition is called opacification of the posterior capsule. It is not necessary to remove the capsule, but only to make an opening in the center of it to allow light rays to pass. This can be easily accomplished using the YAG laser. YAG laser capsulotomy can be performed as an outpatient. The laser makes an opening in the cloudy capsule quickly and painlessly. Most patients note an immediate improvement in vision after the procedure, but it may take several days for full visual improvement to occur. Patients may resume normal activities after YAG laser treatment. The risks of performing a YAG laser capsulotomy are unlikely but include a rise in pressure and a slightly increased risk of retinal detachment.
Need for glasses after surgery?
Although measurements of the eye are taken and used to calculate the required power of the implanted lens, the result is sometimes more short-sightedness or long-sightedness than was planned due to limitations of the formulae available. This means that vision in the distance may not be as good as expected without glasses. In this case, vision is usually good with the appropriate spectacle lens. In extreme cases the intraocular lens may need to be replaced. You may need glasses for distance vision or for reading or both after the surgery.
Astigmatism is due to the cornea not having equally round curves as does a basketball, but having unequal curves like a football. This causes light to be focused unevenly and objects may be seen as distorted or blurred. Astigmatism may arise from tight sutures or from uneven healing of the surgical incision. If sutures have been used they may need to be removed weeks to months after surgery before glasses can be prescribed. Vision may not be clear without glasses. Occasionally surgery may be required to correct the astigmatism.
What are the risks and complications of Cat surgery?
It is generally very safe. However, as with any surgical procedure, occasional complications do occur and a good result cannot be guaranteed. Your vision after surgery will depend on the health of the eye.
Normally side effects:
- Mild discomfort or irritation is usual for a few days after surgery.
- Severe pain is unusual and can indicate the presence of high pressure in the eye or infection. Contact your ophthalmologist.
- Light sensitivity and glare. As the dark Cat is replaced with a perfectly clear implanted lens, more light can get into the eye after surgery. It may take some time to adjust to this. One advantage of this is that colors can seem much brighter than they were before.
- Sub-conjunctival haemorrhage. Some bleeding on the white surface of the eye is normal after surgery. Although this may appear alarming it is generally a painless and harmless condition that may take about 2 weeks to clear.
What type of implant will my surgeon use?
There are many different types of implants available with different characteristics. The majority of implants are monofocal, i.e. have single distance focus and require additional spectacles for near vision.
Multifocal or variable focal implants are available but are not widely used as the quality of vision may not be as good as monofocal implants. Lenses which have the potential to adjust their focus for near and distance vision are also available, although the results are unpredictable.
Achieving distance vision in one eye with a monofocal lens and a degree of near vision in vision in the second eye is another strategy known as monovision or blended vision that can reduce spectacle dependency after surgery.