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Cataract

Cataract

A cataract is the clouding of the crystalline lens in the eye. This natural lens is usually clear and therefore enables light to pass through into the eye for clear vision.

The most common cause of cataracts is age-related changes in the eye. Some of the types of cataracts are subcapsular cataract, posterior subcapsular cataract, nuclear cataract and cortical cataract. As the eye ages, the lens material hardens and yellows. If the cataract is not removed, it will continue to become opaque and may cause blindness eventually.


An eye with cataract usually experiences one or more of these changes:

– Blurring of near and distant vision
– Seeing glares, especially in dimly lit areas
– Colours becoming more dull or less vibrant
– Sensitivity to light
– Frequent changes in glasses prescription

Due to these changes, a person who has developed cataract may find daily activities inconvenient. Reading the newspaper and watching the television may become chores rather than pleasures. Night driving becomes difficult as visibility drops and the eye sees glare from street lamps and oncoming car headlights.

visionbeforeandaftercataractsymptomseffects-day-vision-comp
L: Vision before cataracts (simulated) R: vision after cataracts (simulated)
visionbeforeandaftercataractsymptomseffects-night-vision-comp
L:Vision before cataracts (simulated) R: Vision after cataracts &  halo effect (simulated)

What causes a Cataract?

A cataract may develop in one eye first, then the other. The onset of a cataract is usually due to ageing. An eye with high myopia, acute angle closure glaucoma and chronic anterior uveitis may also develop cataract prematurely.

Some other factors which can cause a cataract are:

  • – Traumatic injuries to the eye
  • – Long-term steroid treatment for autoimmune diseases or after organ transplantation
  • – Diabetes

More uncommon causes for a cataract are concussion, exposure to ionizing irradiation for ocular tumours and long-term intake of certain medications.


When should a Cataract be treated?

The single most effective method to restore vision due to a cataract is to undergo a cataract surgery. This involves the removal of the opaque lens and replacing it with an artificial intraocular lens (IOL).

The surgery typically takes 15-20 minutes per eye and is done as a day surgery. The eye is able to see clearly as soon as the next day after surgery. After resting for 5-7 days, the patient is able to return to work. Most daily activities can be resumed after 1-2 weeks’ rest.

Traditionally, most eye surgeons prefer to wait until the cataract is in the moderate to advanced stage before suggesting a cataract surgery. This is because the older methods of removing a cataract were more complicated. With the intracapsular and extracapsular cataract extraction procedures, bigger corneal incisions with stitching were required. This means a longer recovery period. Also, some patients may end up with residual astigmatism due to the corneal stitches.

The newer method for cataract surgery is phacoemulsification with IOL implantation. With this method, the corneal incision made is smaller of 1.8-2.2mm in length and does not require stitching. This translates to faster wound recovery and less discomfort to the patient after surgery. The doctor is also able to better correct myopia, hyperopia, astigmatism and presbyopia with various types of IOL after removing the cataract.


Can a Cataract be removed at the earlier stages?

Traditionally, most eye surgeons prefer to wait until the cataract is in the moderate to advanced stage before suggesting a cataract surgery. This results in a very hard cataract which may require higher ultrasound energy to break up and remove the cloudy lens during the surgery. As the eye is a very delicate structure, some trauma may be induced to the inner structures when high energy level is applied.

In recent years, more patients and surgeons agree that a cataract can be removed even in the early to moderate stages. As a guide, one should consider undergoing a cataract surgery if the cloudy lens has affected the quality of vision adversely such that day-to-day activities can no longer be done with ease.

With increasing demand for good vision as people are more IT-savvy and retire at an older age, having good quality of vision to carry out tasks are of extreme importance. Undergoing a cataract surgery earlier also means restoring good vision sooner. With the availability of various types of lens implants, surgeons and patients can together make a better decision on the best-suited lens for each individual.

A cataract should not be removed at a hypermature stage also because the lens may start to leak inflammatory materials which can lead to a secondary glaucoma.