WHAT IS A CATARACT ?
A cataract occurs when there is loss of transparency of the lens of the eye . This most commonly occurs with old age. It can also be due to injury, steroid use, inflammation or heredity.
WHEN SHOULD MY CATARACT SURGERY BE PERFORMED?
If the visual impairment from the cataract is affecting the patient’s ability to perform his occupation and activities of daily living e.g. driving, reading, watching tv; or his hobbies e.g. golf, tennis etc; then cataract surgery is indicated.
Patients whose activities need very good vision with low glare eg. pilots, bus drivers and taxi drivers will have their cataracts operated upon at an earlier stage compared to office workers etc who only need reading vision.
Patients who are very active and mobile will need their surgery earlier than those who are bedridden at home.
Usually the cataract surgery is non urgent. Rarely, earlier cataract surgery may have to be done to prevent acute attacks of high pressure in the eye (glaucoma).
Patients with only one good eye should have their cataract operated at a more advanced stage and defer the surgery if they are still managing well as there is a small risk of visual loss with any intra-ocular surgery surgery.
Patients with multiple medical problems should focus on their more serious problems first if the cataract is mild. Old people may have multiple medical problems and it may be wise to focus on the major and urgent problems first and attend to their cataract later when they are stable.
ADVANCES IN CATARACT SURGERY – WHAT KIND OF CATARACT SURGERY SHOULD BE DONE?
Small Incision Phacoemulsification under Topical Anesthesia
Phacoemulsification with IOL implant (Video)
Cataract surgery is now performed through a very small incision (1.8 – 2.7mm). It is done under topical anesthesia i.e. two drops of local anesthetic dropped into the eye as it is almost painless. No injections around the eye, no intravenous injections, no stitches. The patient is prepared on arrival at the surgery suite with a sedative and a painkiller orally. No fasting is needed. The operation usually lasts 15 minutes. The patient can go home after half an hour. Postoperatively, there is usually almost no pain so postoperative painkillers are not prescribed. No patches are needed. The eye is white after surgery and it would usually not be possible for others to tell you just had surgery. If all goes well, you can turn up for office work the next day or go shopping with sunglasses or some protective eyewear. For manual work, it is advisable to rest from one week to one month depending on the risks of accidental injury to the eye. After one month, the patient can go back to full normal activity. The surgery is very safe and effective and serious complications are rare.
Laser Bladeless Cataract Surgery
The latest advances in cataract surgery allows us to perform part of the surgery using a femtosecond laser. No blades are used. The incisions can be performed using the laser instead of with a blade, the opening in the anterior capsule can be cut in a perfectly centred circle, and the cataractous lens can be pre- cut into smaller segments for easier removal, reducing the amount of ultrasonic energy needed. The laser can also correct astigmatism. However the rest of the operation remains the same.
The femtosecond laser for cataract surgery is now available in my practice.
After performing quite a few femtosecond laser cataract surgeries, I feel that the technology is still evolving rapidly and not mature yet. Overall, It is still slightly inferior to small incision cataract surgery with phacoemulsification. The pressure of the suction and the stretching of the eyelids makes it more uncomfortable than cataract surgery. The suction leaves the eye red as opposed to a white eye after small incision phaco-emulsification. The pupil constricts as a result of the laser energy leaving the surgeon with less space and room to maneuver, increasing the risk of complications. Laser decentering and malfunction creates new areas of risks. The procedure becomes longer, as the laser takes an additional 10 minutes, and the laser is not performed under sterile conditions, possibly increasing the risk of infection. Feedback from patients who have had femtosecond laser cataract surgery in one eye and small incision phacoemulsification cataract surgery in the other eye showed that all preferred the standard phacoemulsification procedure.
WHAT KIND OF INTRA-OCULAR LENS (IOL) SHOULD BE IMPLANTED?
Refractive errors and presbyopia (lao hua yen) can be corrected during cataract surgery
At the time of cataract surgery you can take away your high myopia, astigmatism and hyperopia. You can even treat your presbyopia. The aim in cataract surgery nowadays is not only to improve the vision but also to minimize the need for spectacles by allowing the patient to see both far and near without glasses.
This can be achieved by :
1. Monovision using monofocal IOL
2. Slight myopia
3. Multifocal intra-ocular lenses (MF IOL)
4. Accomodative IOL
At the time of cataract surgery, any astigmatism can be treated with Limbal Relaxing Incisions (LRI) or toric IOL.
Monovision Cataract Surgery
A slight imbalance in the refractive error is intentionally created at the time of cataract surgery. The aim is to manage the presbyopia ( lao hua yen). The power of the single focus IOL implanted is calculated to give one eye a zero degree and make that eye clear for distance. That eye will usually be blur for near as there is minimal focusing with the IOL. The other eye will receive an IOL that will make it mildly myopic or short sighted. I usually aim from -0.50 D or 50 degrees to as high as -2.00D or 200 degrees. This allows the second eye to function very well from intermediate to near distances like shopping, reading a desktop computer, reading SMSes , menus, price tags etc. The patient still uses both eyes to some stand and has some degree of binocular vision. The patient may need a pair of reading glasses and/or a pair of driving glasses. If the patient wants good vision with both eyes at the same time, this can still be easily achieved with spectacles without any giddiness as the imbalance is mild. Clinical trials and patient feedback has shown that this is still the most acceptable way of achieving spectacle independence and a good range of distance and near vision with excellent visual quality.
Accomodative Intra-ocular Lens
These attempt to restore the focusing power of the eye by allowing forward and backward movement of the intra-ocular lens (IOL). The Human Optic and the Crystalens are some examples. However, the focusing power is weak and reading glasses are often still needed. The advantage is that there is none of the glare, starbursts, poor night vision and loss of visual quality that is associated with multifocal IOLs.
Multifocal Intra-ocular Lens (MF IOL)
Another way of treating the presbyopia (lao hua) is with multifocal IOLs. Most multifocal intraocular lenses split the light into two focal points. This results in the eye being simultaneously in focus for both distance and near objects and provide acceptable spectacle independence for some patients. No imbalance between the two eyes is created so the stereoscopic vision is unaffected. However, as the light entering the eye is split into two focal points, there is somepermanent loss of brightness and sharpness. There will also be glare,haloes and starbursts around street lights and headlights of cars at night, against the sun and in other high glare situations. These cannot be corrected with glasses. In addition, if there is residual astigmatism and myopia of 75 degrees or more, the additional blurring may be unacceptable and glasses will be needed. Complete spectacle independence is still not achieved in a large proportion of patients. MF IOLs are suitable for patients who do not want to wear spectacles, who are not fussy about the quality of their vision, and who cannot tolerate a mild imbalance between the eyes. They are only to be used in patients who do not have visual impairment from retinal or optic nerve conditions as they reduce the quality of vision.
Lentis Mplus Multifocal IOL
This is the latest multifocal intra-ocular lens and probably the best multifocal IOL. Unlike conventional multifocal diffractive or refractive IOLs which have multiple concentric rings, these lenses look like a bifocal spectacle lens with the top part being in focus for far and the bottom for near. The results so far appear superior to the concentric multifocal IOL in terms of brightness and less glare and halos. An example is the Lentis M-plus IOL. This is my present choice of multifocal lens if the patient decides to have a multifocal implant
HOW WILL I FEEL DURING AND AFTER CATARACT SURGERY?
This is a 15 minute outpatient procedure performed under topical anesthesia. Two drops of local anesthetic are used to numb your eye. No injections to your hand or eye area is needed. During surgery, you may feel some pressure and aching but no sharp painful sensations. You can see some light and shadows and can feel the cold water splashing your eye. You are given a sleeping tablet to calm you down and a painkiller as well. In the very rare event that you are unable to tolerate the sensations, an anesthetic injection can be given midway through surgery after which the eye will be completely numb. No stitches or eye patching is used. You may use your eye immediately after the surgery and can watch tv or read the same day although it may be a bit blurry. There is little postoperative discomfort, only a slight scratchy or foreign body sensation. No painkillers are prescribed post-operatively. You have to report 2-3 hours before the scheduled time of the surgery . You can go home half an hour after the end of the surgery.
RESULTS OF CATARACT SURGERY
99 % will have no complication and rapid visual recovery within a few days. 90% will have achieved within 0.5 D of the targeted refraction. 1% may have a posterior capsular rupture. This will result in the vitreous gel entering the front of the eye. This gel has to be removed surgically and the operation will then be extended by 30-60 minutes. An anesthetic injection near the eye may be needed if this happens.
You will usually be able to perform office work the next day or within a few days. An eye shield must be worn when sleeping for two weeks. No vigorous sports should be performed for 2-4 weeks and no swimming is allowed for a month. However you may go out the next day provided you wear sunglasses or the protective glasses provided for you. After 2 weeks, you may engage in light non-contact sports like jogging or going to the gym or practicing taichi. There should be no ball games. After one month, you may resume full physical activity. When all goes well as in 99% of cases, the eye is not inflamed nor red at the end of surgery, and your friends will not realize you have had surgery unless you tell them.
The most common complication is that of a rupture of the membrane keeping the vitreous gel at the back of the eye from coming to the front. This is called posterior capsule rupture and the incidence is about 1%. This is usually not serious but may result in a longer operation and a slower recovery of vision. The best corrected vision may be slightly compromised. The most feared complication is that of infection. This is called endophthalmitis. Bacteria may enter the eye during surgery and grow causing severe inflammation and pus formation within the eye. The vision may be very badly and permanently damaged. This usually happens on the first or second day after surgery. There will be redness and pain and blurred vision. This is an emergency. Fortunately it is very rare. The risk is 1 in 6,000 to 10,000 cataract surgeries. To prevent endophthalmitis, antibiotics are routinely instilled within the eyeball at the end of surgery. Additionally, the patients have to instill 2 different antibiotic eyedrops hourly for 24 hours. The surgery is performed in a specialised eye theatre in Mount Elizabeth Hospital performing only eye surgeries with specialized eye nurses and staff who understand the importance of sterility and asepsis. To prevent bilateral endophthalmitis, it is best to perform the surgery one eye at a time and to do the second eye a few days later.
WILL MY CATARACT GROW BACK?
No. However 10% of of patients may experience blurred vision months to years after cataract surgery. This may be because of posterior capsule opacification.
A membrane behind the IOL slowly turns opaque and loses its transparency. This results in glare and loss of sharpness. This can easily be treated with a one-time application of a laser. The procedure is called a YAG laser capsultotomy.
A central hole is made in the membrane and the vision is restored rapidly and safely. There is no pain and complications are rare. The patient can go back to work the next day. The procedure does not have to be repeated.
DOES MY IOL NEED TO BE REPLACED?
No. The IOL is made of a very durable polymer and will last a lifetime. IOLs implanted shortly after the second world war are still clear to this day. It is very rare for an IOL to lose its clarity over the years and this happened to certain brands of IOL. Still, it is wise to be cautious about trying out IOLs made of new materials until a few years have passed.