Cataract Surgery Restoring Vision with New Techniques and Innovations Cataracts represent a clouding of the lens of the eye. Light rays w hich enter the eye are blocked or scattered, resulting in problems such as blurred vision and glare. Some patients even experience double vision. In most cases, cataracts develop as a result of aging changes in the eye. Cataracts may also be caused by other diseases like diabetes, as a side effect of some medicines, and from injury to the eye. There are no medicines w hich can cure a cataract. How ever, cataract surgery has become very successful and is one of the most common eye operations performed w orld-wide.

Important Advances in Cataract Surgery

Phacoemulsification Phacoemulsif ication refers to surgery where the cataract is broken up w ith ultrasound energy and removed through a small incision. Because surgery is performed through such a small incision, recovery is rapid. Many patients achieve good vision by the f irst day after surgery. In most cases, stitches are not needed, resulting also in faster recoveries and better comfort after the operation. Because phacoemulsif ication is a fast and safe operation, most patients have surgery as a day case procedure. The surgery itself usually takes 20-30 minutes, and is a painless procedure.

Figure 2 Small incision phacoemulsif ication cataract surgery.

a The cataract is first broken up and remov ed with

ultrasound wav es from a hollow needle.

b An intraocular lens is injected.

Figure 2a

Figure 2b

Dr Por Yong Ming MBBS (Melbourne), FRCS (Edinburgh), FRCS (Glasgow), MMed (Ophth)(Singapore), MRCOphth (London) Dr Por graduated from the University

of Melbourne in 1997 with honours and began ophthalmic training in the United Kingdom in 1999. While in the

UK, he trained at the Manchester Roy al Eye Hospital. He then returned to Singapore in 2001 and worked at

the Singapore National Ey e Centre. He presently practices at Jerry Tan Eye Surgery at Camden Medical

Centre.

Dr Por's strengths are in ref ractive surgery , phacoemulsification cataract surgery , v arious forms of corneal

transplantation including anterior and posterior lamellar grafting, and external eye diseases. He is also

trained as a comprehensiv e ophthalmologist and has extensive experience treating other ey e

diseases including glaucoma.

Figure 1a A normal eye.

Figure1b A cataract blocking light entering the

eye, causing blurred vision.

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Lens Implants Because a cataract operation removes the natural lens of the eye, lens implants are needed to replace the original cloudy lens. By implanting lens replacements, there is no need for thick glasses or contact lenses after surgery. Furthermore, by customizing the lens implant, cataract surgery has become one w here vision can be enhanced and w here spectacle freedom becomes possible.

Customizing Lens Implants Various formulas have been invented based on the eye’s corneal curvature as well as the length of the eyeball, to help choose the best lens for the low est spectacle pow er. Almost all degrees of long or short sightedness can be corrected in this way. Measuring the length of the eyeball has traditionally been accomplished by using an ultrasound machine. More recently, using a laser beam w ith the IOLmaster machine has allow ed this measurement to be done w ith 5 times greater accuracy. In most cases, using such an instrument to predict the f inal pow er of the eye results in refractive power of +/-50 degrees (0.50 dioptris) after cataract and lens implant surgery.

Correcting Astigmatism and Presbyopia Astigmatism and presbyopia are 2 other problems for which people require spectacles to see clearly. Of late, 2 new lenses have helped to solve these problems. Where a toric lens w as traditionally used in a pair of spectacles for astigmatism, they are now available as lens implants to be used during cataract surgery (Figure 3a). These toric lens implants correct astigmatism of as high as 400 degrees. In order to achieve astigmatism correction, the lenses must be aligned exactly according to the direction of astigmatism of the patient’s cornea. Specialised photographs and planning programs help in deciding the optimal position for the lens (Figure 4a and 4b). In combination w ith accurate biometry w ith the IOLmaster, they virtually remove the need to w ear glasses for distance.

To address presbyopia (rabun tua), mult ifocal lenses are now the most w idely employed method. These lenses are most commonly diffractive in nature, which means they use a series of rings etched on the lens surface to split incoming light rays into 2 foci-one distant focus and one near focus (Figure 3b).. They have several disadvantages. Firstly, the presence of the rings means that in certain situations, and especially at night, light sources w ill appear w ith a halo and ring around them. Contrast is reduced and images may appear a little darker.

The other type of lens that is sometimes used to address presbyopia is the accommodating lens (Figure 3c). These lenses are f lexible, and this property allow s changes in their position w ithin the eye to take place. This allows their focus to shift, allow ing clear near as well as far

Figure 3a A toric lens

Figure 3b A multifocal lens

Figure 3c An accommodativ e lens

Figure 4a Planning a toric lens implantation. First, the optimal position of the lens is determined

using a specialized computer program

Figure 4b A photograph of the

ey e is taken, and a protractor is ov erlaid to help with lens

positioning

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vision w ithout the halos and reduced contrast seen w ith mult ifocal lenses. How ever, their effect is not predictable and the movement of the lens may not be enough in some patients. The perfect, fully accommodating intraocular lens remains a target of research for ophthalmic scientists. In conclusion, cataract surgery has progressed rapidly in the last few decades. From having to w ear thick glasses after surgery and lying in a hospital bed for a week, to current day case surgery and better spectacle free vision than ever. In the future, femtosecond lasers will speed up cataract surgery and improve safety, and w e await the holy grail of lens implant surgery-the fully accommodative lens implant which w ill return our vision to a state truly like that of a young eye.

Advances in Lens Implants

Toric lens • Corrects astigmatism of up to 400 degrees

• Patients with more than 100 degrees of corneal astigmatism will benefit

• Most patients do not have to wear glasses to see in the distance after surgery

• Requires precise alignment to achiev e effect

Multifocal Lens • Giv es reasonably good vision at near (about 1foot) and in the f ar distance

• Most patients do not need to wear spectacles at all after surgery

• Best for patients with minimal astigmatism

• Requires very accurate measurements of the ey e

• Causes halos around lights, especially at night

• Causes decreased visual contrast compared with a normal monofocal lens

Frequently Asked Questions About Cataracts and Cataract Surgery

Q: Who requires cataract surgery? A: Once a patient develops cataract that is dense enough to blur vision even w hen wearing glasses, he/she will benefit from surgery. Q: Will cataracts cause blindness? A: If left alone, cataracts will slow ly become denser over time, and cause vision to become blurrer. By themselves, they do not cause total blindness, since they can be operated on even w hen very dense. Sometimes, very dense cataracts can cause a severe kind of glaucoma. If this develops, permanent blindness can result. Q: How long does it take to recover from cataract surgery? A: Recovery of vision after cataract surgery is very fast. In most cases, vision the next day after surgery is good enough to do most things like w atching television and even driving. How ever, patients should remember that there is still a w ound in the eye w hich takes up to a month to heal. They should not rub their eyes and avoid activities where a lot of w ater gets in the eye, such as sw imming. Besides this, the spectacle pow er of the eye takes about one month to stabilize, and patients should w ait for this period of time before getting new spectacles. Q: What can I do to prevent cataracts? A: Cataracts are usually an age related problem, so they cannot be totally prevented. How ever, studies have show n that a diet rich in certain nutrients may delay the onset of cataracts. These foods include colourful fruits and vegetables which contain antioxidants such as vitamin A, C and E. Lutein is another antioxidant and is found in dark green leafy vegetables. Finally, it has been show n that smoking causes cataracts to develop faster and smokers should quit as soon as possible.

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