What is Cataract?

Our lens works like the lens of a camera. The lens focuses light onto the retina and a clear lens is the key of clear vision. Once it becomes opaque and affects our eyesight, an eye disease called cataract may have already developed.

Causes of cataract

Around 90% of the cataracts in Hong Kong are due to aging. The lens hardens and becomes less transparent.

The other causes include:

Excessive ultraviolet-light exposure

Smoking

Young adults may also develop cataract if they have:

High myopia

Diabetes

CMER Eye Center_ Cataract causes_ Steroids

Use of certain medications eg. Steroids

Congenital cataract

Eye trauma

Symptoms of cataract

Clouded or blurred vision

Sensitivity to light, glare and have double vision

Dim or distorted vision

Decreased night vision

Frequent changes in prescription for
eyeglasses or contact lenses

Treatment of cataract: Minimally Invasive Surgery

CMER Eye Center_ treatment of cataract_ intraocular lens

CMER Eye Center_ treatment of cataract_ cataract surgery

As there are no medications that can restore clear eyesight from cloudy vision resulting from cataract, surgery is the treatment.

The mainstream of cataract surgery is phacoemulsification combined with intraocular lens (IOL) implantation. The surgery is performed through an incision less than 3 mm in diameter. The cloudy lens will then be emulsified into tiny fragments by ultrasound and sucked out. Finally, an intraocular lens will be implanted. The surgery only takes 10-20 minutes and most of them are performed under topical anaesthesia (by applying numbing eye drops). The incision normally seals without stitches.

CMER Eye Center_ treatment of cataract_ phacoemulsification

The cloudy lens is removed by a micro ultrasonic instrument.

CMER Eye Center_ treatment of cataract_ intraocular lens (IOL) implantation

Implantation of an intraocular lens.

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The incision normally seals without stitches.

Comparison of Intraocular lens (IOL)

Cataract surgeons could customized the IOL planning for their patients according to their visual needs.

With the pre-operative assessment, patients can discuss with their ophthalmologists on the selection of IOL according to their ocular condition, vision needs and financial situation, etc. IOLs could be divided into three types,

Type of IOLs	Monofocal Lens	Toric Lens	Multifocal Lens
Distant vision (e.g. Driving, watching TV)	Excellent	Excellent	Good
Mid-distance vision (e.g. Using a computer)	Excellent (May require Blended Vision)*	Excellent (may need glasses)	Good
Near vision (e.g. Reading distance)	Excellent (May require reading glasses)	Excellent (may need glasses)	Good
Advantages	Good vision quality (However, can not have good distant and near vision at the same time.)	Good vision quality Correct astigmatism	Gain good distant, mid-distance and near vision Most of the patient could get rid of glasses
Suitability	• Does not mind wearing glasses • Seeks for better visual performance • Has financial considerations	• Previously diagnosed with astigmatism • Does not mind wearing glasses • High demands on visual quality	• Prefers not to wear glasses • No financial consideration • No other vision-affecting ocular diseases • Infrequent night driving

Blended Vision
Blended Vision, also known as Mono-Vision, works by implanting two IOL with different powers, both eye work together for different visual distance thereby reducing the symptoms of presbyopia. A period of adaptation will be needed for the patients.
In Blended Vision, one eye will be used for far objects (about zero diopter) and the other will be used for mid-distant objects (about 1.0 to 2.50D myopic diopter). Theoretically, most of the daily activities can be done without glasses when seeing with both eyes.

Frequently asked questions (FAQ)

Do we need to wait until the cataract get mature？

With the advancement of cataract surgery and IOL technology, modern cataract surgery is more effective. Patients can consider earlier cataract surgery as it is more difficult to be removed and the risk of complications will be higher if a cataract is more mature.

Therefore, patients should consider cataract surgery when their works and daily lives are affected. But it is a totally different story in the old days when there was no intraocular lens for implantation after a cataract surgery. Patients had to wear thick glasses to compensate after the lens was removed. The worse thing is, if only one eye was operated, the huge difference between two eyes would make people feel bad. Therefore, people consider surgery only until the cataract was mature. Even the ophthalmologists would suggest patients to have their cataract removed when it became mature in the old days.

How long do IOLs last? Do they need to be replaced?

IOLs are placed permanently in your eye and will not "wear out". IOLs need to be replaced only if IOLs shift out of its original position or it is damaged. There is a very small amount of patients who cannot adapt to the implanted IOLs (around 2% in multifocal IOLs and it is much less in that of monofocal IOLs).

Do I need to wear glasses after the surgery?

Your doctor will customize the target refraction according to your daily visual tasks and visual demands. Some of the patients may not need glasses after surgery if the target refractions fit their needs well. For those who require a better vision quality, they can be prescribed with glasses in order to assist them to gain a better vision for different purposes.

Will I have painful feeling during the surgery?

Cataract surgery is performed under topical anesthesia (by applying numbing eye drops). Patients are awake during the surgery, but usually they do not feel pain.

Does cataract surgery need to be done in hospital?

Cataract surgery is a minimally invasive surgery which does not require general anaesthesia which only eye drops are needed in most cases. Therefore, cataract surgery does not have to be performed in hospital medically. Our international standard operating theatres, which equipped with advanced machines and technology for preoperative assessment and surgical procedures, ensure a safe and reliable cataract surgery.

However, some patients may need general anaesthetic and be treated in the hospital. For further information on surgical planning, please ask your ophthalmologist for more details

When can I resume daily activities/ exercises after cataract surgery?

Patients can resume light exercise such as tai chi, walking or hiking if no abnormalities are found in day 1 post-operative follow-up. However, contact sports such as boxing are not recommended for a period of time. Please consult your doctor for more details and here below are some examples,
Walking: 24 hours after the surgery
Air travel: 24 hours after the surgery
Swimming: 1 week after the surgery to reduce the risk of infection
Other facial or dental treatments: at least 1 week after the surgery. For the safety reason, it is better to be 1 month after the surgery.

Cataracts