Cataract

 

What is cataract?

 

Cataract is the age-related clouding of the lens (Figure 1). Contrary to locals’ belief, it is not a "layer” growing across the eye!


Figure 1: Image of a very advanced ‘white’ cataract

 

What causes cataract?

 

Cataracts are more common in the elderly as the natural lens gets progressively more cloudy with age. Sometimes, cataract can be present at birth as well.

Certain types of illnesses (like diabetes), prolonged use of certain medications (like steroids) and prolonged UV exposure are some of the other causes of cataract. Injury to the eye can also result in cataract formation.

 

What are the symptoms of cataract?

 

The most common symptom is blurring of vision (i.e. like looking through a dirty window - Figure 2). Other symptoms may include colours appearing dull, glare and haloes around lights, difficulty reading, watching TV or driving at night.

Cataract is the leading cause of blindness in the world and in Malaysia, from a national eye survey which was carried out to determine the prevalence and the major causes of visual impairment among our population; approximately 2.5% of our population were visually impaired and about 50% of blind people were blind from cataract.

Figure 2: Blurred vision with cataract (right)

 

Treatment of cataract

 

The only proven ‘cure’ for cataract is surgery. Unfortunately, there is no eyedrop or medication which can treat a cataract. Cataract surgery has undergone tremendous technological advancement over the past half century. Gone are the days where cataract surgery involved large incisions in the eye performed under general anaesthesia followed by long hospital stays, slow recovery and thick glasses. Instead, modern cataract surgery is a day surgical procedure using only eyedrops as to numb the eye, rapid recovery and even complete spectacle independence in some patients.

Modern cataract surgery is called phacoemulsification (Figure 3) and this technology involves the use of high frequency ultrasound (not laser as everyone believes) delivered through a handheld probe to break the cataract into little pieces which are subsequently removed piecemeal. An artificial lens implant is then placed into the eye and this implant remains inside the eye for the rest of the patient’s life. It does not need to be removed or exchanged unless in exceptional circumstances. The whole procedure is carried out through an incision of less than 3mm in length and no stitches are required.

Figure 3: Modern cataract surgery done using a microscope (surgeon’s view on the right)

 

The latest development in cataract surgery is the use of a femtosecond laser to perform cataract surgery. This is true "laser" cataract surgery and has only been available for the last 2 years or so. The technology has only recently arrived to this part of the world and currently, it is still in its infancy. The femtosecond laser allows for very precise surgery and has a lot of potential but currently there is still a need to use it together with our conventional ultrasound method and it is very expensive.

 
 

Spectacle independence

 

Traditionally, cataract patients have always been told that they will still require glasses after surgery and before the invention of intraocular lenses, very thick glasses were needed. Since the introduction of intraocular lenses in the 1950s, patients could do without glasses for distance vision but near vision would still require reading glasses. This is because the lens implanted is a monofocal lens; i.e. this lens enables clear vision without glasses, only for distance.

In recent years, multifocal lenses have become available which enable clear vision at different distances without glasses. The modern cataract patient also has more visual demands; i.e. good distance vision for driving, good intermediate vision for computer and good near vision for reading. With the introduction of these multifocal lenses, the ability to perform all these tasks without glasses has become a reality.

Another new type of lens available recently is the toric intraocular lens. Traditionally, the intraocular lenses could only correct near sightedness or far sightedness; i.e. if the patient had near sightedness or far sightedness before cataract surgery, implanting an appropriate powered lens allows the patient to see clearly(for distance) without glasses after surgery. Previously, if the patient had astigmatism before surgery, there was no lens available to correct this and even after cataract surgery, they would require glasses all the time. Toric intraocular lenses have now addressed this problem.

Another step up is the availability of a combination of toric and multifocal lenses which further adds to the list of options available to the patient who desires to be glasses free after cataract surgery. (Figure 4)

Figure 4 - Some examples of the different types of intraocular lenses available

 

With such a multitude of options available to the cataract patient, it is important that firstly, the patient is made aware of these options and secondly, for the surgeon to help the patient make an informed decision about the choice of implant to match the patients’ visual requirements.