Q1. What is cataract?
Cataract is the clouding of the crystalline lens that causes blurred vision. Light enters the retina through the cornea and crystalline lens. It will be blocked if the crystalline lens becomes opaque and cloudy, resulting in blurred vision.   
Q2. Who is more likely to have cataract?
As a degenerative process, cataract can occur in all of us. Cataract occurs when the crystalline lens degenerates with age, probably earlier in some people such as frequent sunbathers. They are more prone to cataract due to UV exposure. Patients with diabetes and eczema are also more likely to get cataract. It also occurs earlier in people on long-term steroids. 
Q3. What is the best time for cataract surgery?
As far as timing is concerned, there isn’t a definitive answer. Surgery should be considered when cataract affects your vision or daily life.
Q4. How is cataract surgery performed?
Cataract surgery can be done either under local anaesthesia, monitored anaesthetic care or general anaesthesia. Patients under local anaesthesia will remain conscious but feel nothing during the procedure; while those under monitored anaesthetic care or general anaesthesia will remain unconscious during the surgery. When one is under anaesthesia, doctor will make a small incision of about 2.2 mm to 3 mm at the cornea, through which phacoemulsification is performed with an ultrasonic probe to chop and aspirate the cataract. A foldable intraocular lens will then be implanted via the same incision after removal of cataract. As the wound is miniscule, suture is not required after surgery. The entire procedure takes about 15 to 30 minutes.
Q5. How is intraocular lens selected?
There are many different types of intraocular lens (IOLs), and it basically depends on if one wants to improve astigmatism or not.  Some patients may choose the type that can improve their astigmatism, so that they can enjoy clear vision after surgery without wearing glasses of astigmatism. Other choices are monofocal lens implants, multifocal lens implants or Extended Depth of Focus (EDOF) lenses.
What are the differences between all these of IOLs? Monofocal lens implants have only one single focus. It can achieve sharp and clear vision when focused. But the same advantage makes it less convenient: one may fail to see distant objects clearly when near vision is fine, and vice versa.  It can be addressed with “monovision”, where one eye is focused for distant vision and the other is left somewhat shortsighted to see close objects. Together they can achieve clearer near and intermediate visions. As the eyes have different focuses, it takes time for patients to adapt well to monovision. Also, you may still need to wear glasses when looking at very close objects or reading small print. All in all, monovision is simple and affordable. You don’t have to pay for different IOLs.
As the name goes, multifocal lens implants have more than one focal point, usually two or three. Vision is the clearest at the focal points, and a trifocal IOL can achieve satisfactory distant, intermediate and near visions. However, as the same light source is focused at three focal points, the image may be dimmer with poorer contrast than that of monofocal lens implants. Though satisfactory, the vision may be not as sharp as expected. Your doctor will explain to you the advantages and disadvantages of multifocal lens implants, and you may considered if you prefer convenience to sharp vision or otherwise. 
With an elongated focus, Extended Depth of Focus (EDOF) lenses give an extended depth of vision. For objects at farther focal points, EDOF lenses can achieve satisfactory distant and intermediate visions. But they are less convenient than multifocal lens implants as they fail to give a wider depth of vision when the objects move from far to near, thereby resulting in blurred vision. EDOF lens is somewhere in between: it is more convenient than monofocal lens implants, but less satisfactory than multifocal lens implants when near vision and depth of vision are concerned. You doctor will discuss with you and choose the most appropriate IOLs based on your needs, lifestyle or interests.
Q6. What is the post-operative care?
Cataract surgery has its own risks as other surgeries, though not very high under normal circumstances. As high risks do exist, patients should know and understand them before considering surgery. They should also be familiar with post-operative care: keep the eyes clean and prevent water getting into them, especially when taking a bath and washing face. To avoid rubbing eyes during sleep, wear an eye shield for a week after surgery. Use eye drops as instructed to prevent possible inflammation after surgery. Antibiotic eye drops and steroid eye drops are usually prescribed for one to three weeks for recovery of the eyes. Wearing sunglasses on sunny days can help block sunlight and UV and minimise discomfort during recovery. You may just resume normal activities, go out as usual and do simple stretching.

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