A cataract is a condition in which the crystalline lens of the eye becomes opaque, preventing sufficient light rays from entering the eye, hence impairing vision.

Cataracts are the leading cause of blindness in the world and they develop for a number of reasons: Prolonged exposure to UV light, long-term use of certain medications, hypertension, old age and as a secondary effect of diseases such as diabetes, to mention a few. In the young, cataracts can be present at birth or can develop as a result of injury.

The most common and advanced cataract surgery technique is phacoemulsification (performed as a day/ambulatory surgery). At the Singapore National Eye Center (SNEC), 91.5 percent of cataract surgeries are performed by phacoemulsification.

In phacoemulsification, a handheld instrument driven by ultrasound is used to emulsify and aspirate the cataract lens out of the eye through an incision as tiny as 1.8mm. The instrument has a metallic tip, which vibrates at a very high speed. The device that drives this vibration is housed in a machine that controls the flow of fluid into the eye.

The entire system is important in keeping the eye stable and fluidics correct to allow the surgeon to operate safely and efficiently. The surgery is complete with less discomfort, a more rapid rehabilitation of vision and with the possibility the patient will no longer have to rely on spectacles.

Once the cataract-damaged lens has been removed, an artificial intraocular lens (IOL) is implanted. This implant measures about 12.5mm in length; it is inert and stays in the eye forever.

Prior to the development of IOLs, cataract patients were forced to wear thick glasses or contact lenses after surgery; they were essentially blind without their glasses. However, there has been remarkable improvement in the designs of these IOLs over the years. Currently, most IOLs used in phacoemulsification are made of either silicone or acrylic. These materials make the IOLs pliable. Hence, they can be folded or rolled to be placed into the eye.

In addition, there is also an array of IOLs ranging from "multifocal" to "wavefront", "yellow", "toric" and many more. The new "multifocal" and accommodating IOLs offer the possibility of seeing well at more than one distance and solving more vision problems than ever. Earlier designs had problems with glare but the current ones seem to work much better and are popular.

On the other hand, the "wavefront" IOLs can help reduce or omit aberrations of images that we sometimes see, especially in the dark when our pupils are larger. "Yellow" or blue-blocking IOLs help block out the blue light that is believed to harm our macula and causes degenerative changes (all IOLs have ultraviolet tint anyway, to protect eyes against the sun's rays). "Toric" IOLs, like Toric contact lenses, are used in cases with a significant amount of astigmatism, so as to correct the astigmatism during cataract surgery. The concept has been around for some time, but it is only the current designs that have shown better predictability and stability of results.

As cataract patients are becoming more involved and demanding with their choices, the trend of cataract surgery would be to provide vision for all activities without glasses. To achieve this, an accurate measurement of the eyeball before surgery is crucial. This requires the use of state-of-the-art machinery by experienced technicians so as to obtain accurate results used in choosing the right IOL power to use during cataract surgery.

Astigmatism for example, can be corrected in cataract surgery with use of a "toric" IOL or by performing Limbal Relaxing Incisions during the cataract surgery. These incisions are placed near the outer border of the cornea to modify and correct back the shape of the cornea, hence, correcting astigmatism.

One major challenge faced by surgeons in cataract surgery is to achieve accurate refractive results in patients who have had previous LASIK or other corrective surgeries. These procedures change the shape of their corneas and may pose inconsistent results during eyeball measurement when calculating their IOL power. However, with sophisticated new machinery and calculation formulas, the results after cataract surgery for these patients are proving to be very accurate.

In medicine, new concepts and technology constantly surfaces and the SNEC has been instrumental in bringing advanced microsurgical techniques and lens implant technology to the nation and region.

For almost two decades now, SNEC has been treating cases of poor eyesight in local patients as well as from overseas. Cases range from cataract to LASIK surgeries to potentially blinding conditions such as cornea and retinal diseases.

The SNEC now attends to 250,000 outpatients -- including 16,000 foreign patients -- and performs 14,000 major eye surgeries and 13,000 laser procedures annually. The high quality and volume of SNEC's services has seen the institution become the leading eye center in the Asia-Pacific region and beyond.

Dr Sharifah Zainah Alsagoff MBBS, MMed (Ophthalmology), FRCS (Ed) Consultant and Deputy Head, Cataract and Comprehensive Ophthalmology Service, Singapore National Eye Center.

Articles in this column, which will appear every two weeks, are provided by a panel of doctors from www.flyfreeforhealth.com, a leading multimedia medical tourism platform dedicated to providing travel and lifestyle incentives for those adopting a healthy lifestyle.

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