Cataract Surgery

A cataract forms when the normally clear lens of the eye becomes cloudy, causing blurry vision. The normal lens focuses light onto the back of the eye so that images appear sharp. The clouding of this lens when a cataract forms distorts vision. Cataracts usually form gradually and are age related but can also develop rapidly. They often affect both eyes, but it is not uncommon for a cataract in one eye to form more quickly. Cataracts become more common, as people become older.

It is uncertain precisely why cataracts occur. Most cataracts are thought to be caused by changes in the protein structures within the lens over a period of years so that the lens become cloudy. Rarely, early childhood cataracts or cataracts in the new-born may be a result of genetic disease, hereditary enzyme defects, or systemic congenital infections. Formation of cataracts can also be hastened by severe trauma to the eye, eye surgery, or intraocular inflammation. Excessive ultraviolet light exposure, exposure to ionizing radiation, smoking, diabetes mellitus, or the use of certain medications, such as oral, topical, or inhaled steroids, & statins have been thought to be associated with promoting cataract formation.

Apart from blurred vision, cataracts cause difficulty with glare (in bright sunlight or vehicle headlights when driving at night), dull colour vision, difficulty with reading and near vision, and frequent changes in spectacles prescription. Initially, a change in glasses may help when vision begins to change from an early cataract. However, stronger glasses or contact lenses will no longer improve the vision as the cataract develops and becomes more dense and cloudy.

Eye pain, redness or tiredness is usually not associated with cataract. As cataracts usually develop gradually over months or years, any more rapid or painful changes in vision suggest other eye diseases. If in doubt, there should be an urgent or early evaluation by an ophthalmologist.

Cataracts are uncommon before the age of 40, but once cataracts do develop, an eye care specialist may mention during a routine eye examination that you have early cataracts, even if you have not noticed visual blurring or other symptoms. However, generally you will be the first one to notice changes in your vision that may require cataract surgery. Most people will not begin to have symptoms from their cataracts until many years after the cataracts start to form. It is reasonable to consult your ophthalmologist at regular intervals to monitor your cataracts. A cataract can be safely observed without treatment until you notice changes in your vision.

When you develop significant vision loss directly because of the presence of cataract, then cataract surgery is normally recommended. However, your ophthalmologist may not recommend surgery if you also have other significant eye disease, unconnected to cataracts, that impairs your vision. If it is necessary to perform cataract surgery to remove a cataract that resulted from eye trauma or previous eye surgery, so that the eye specialist is able to see the retina at the back of the eye, this may be appropriate in order that the ophthalmologist can assess the retina or optic nerve for further treatment. Cataract surgery is usually performed under local anaesthesia and typically takes less than 30 minutes, but account is taken of the individual’s coexisting medical conditions and the mode of cataract surgery is personalized for the individual.

An optician or ophthalmologist can diagnose cataracts by detecting opacities in the lens during a medical eye examination. The lens of the eye affected by cataract formation can be seen using a variety of specialized viewing instruments. An eye care specialist is able to tell how much a cataract may be affecting vision by employing the usual eye tests include testing visual acuity using a Snellen chart, colour vision, glare & contrast sensitivity, and a thorough examination of all other parts of the eye. It is important for the ophthalmologist to exclude diabetes mellitus, glaucoma and macular degeneration by performing a thorough examination.

If your cataract does not affect your daily life in any way, or if you are not keen to have surgery, it is not imperative to undergo cataract surgery. Most cataracts develop slowly with age, and many patients do not notice loss of vision until it is quite advanced. It is not possible to predict with certainty how rapidly cataracts will develop and some cataracts remain less dense and do not progress to the degree where they cause blurred vision severe enough to require cataract surgery. Some cataracts progress more rapidly. Your ophthalmologist will assist you in making your own individualized choice about whether and when to proceed with cataract surgery. The ophthalmologist will be able to advise you how much of your loss of vision is due to cataracts and what sort of visual improvement you can expect if you choose to have cataract surgery.

Nowadays, the most common form of cataract surgery involves a process called phacoemulsification. Using an operating microscope, your ophthalmic surgeon will make a very small incision in the surface of the eye in or near the cornea and then inserts a thin probe into the eye. The ultrasound probe uses ultrasonic vibrations to dissolve the clouded lens. These tiny fragments are then suctioned out through the same ultrasound probe, following which an artificial lens is placed into the thin capsular bag that the original lens previously occupied. This artificial lens is required to help your eye focus following cataract surgery.

Other less common techniques for cataract surgery nowadays are Extra-capsular cataract surgery and Intra-capsular cataract surgery, but may be appropriate in such cases as extremely advanced and dense cataracts, or where there has been previous significant eye trauma.

The natural lens of the eye helps focus the light for sharp vision, An artificial lens is implanted at the time of cataract surgery as a replacement for the natural lens because it gives the best visual outcome. As the artificial lens implant is placed in or near the original position of the removed natural lens, virtually normal vision is restored. Artificial lenses typically stay permanently in place, are maintenance free, and are not felt by the patient and not noticed by others.

The following is a summary of the available types of artificial lenses:

1. Mono-focal lens are the most commonly implanted lenses nowadays. They can provide very good distance vision, supplemented often with a light pair of glasses. Mono-focal lenses provide sharpest focus at only one distance and they do not correct pre-existing astigmatism, which is due to irregular corneal shape that tends to distort vision at all distances. Reading glasses are often needed by patients who have had mono-focal intraocular lenses implanted. With mono-focal lenses, it is possible to choose to aim for good close vision instead, as this is particularly suitable for those who wish to do a lot of detailed close work or prefer to be able to read without glasses. Glasses for distance will then be required. A final option, using mono-focal lenses, is so-called “Monovision”, which aims to provide a combination of distance vision in one eye and near vision in the other. The purpose is to minimize the need for glasses, but Monovision may result in some visual difficulties which may be difficult to get used to. Monovision is not always ideal and should be chosen only after very careful consideration.

2. Toric lens are suitable for correcting astigmatism as well as short-sightedness. Due to the difference in lens power in different areas, the correction of astigmatism with a toric lens requires that the lens be positioned in a very specific configuration. There is a risk that if the toric lens rotates, a second operation may be needed to rotate it back into position for best vision, or sometimes to remove it and replace with a standard lens. With toric lenses, patients are still likely to need corrective glasses for all near tasks, such as reading or writing.

3. Multifocal lens, one of the latest advances in lens technology, may allow some individuals to see at a variety of distances, including near, intermediate & distance. However, multifocal lenses are not suitable for everyone as they cannot correct astigmatism, and patients may still require spectacles or contact lenses for clearest vision.

Just before surgery, your ophthalmologist or associate staff member will inform you about the steps that will occur during surgery, ask you about your medical history and perform a brief physical examination. Always inform your ophthalmologist about medications you are using and discuss if any should be avoided prior to surgery. Always inform your ophthalmologist if you have had previous laser treatment (e.g. LASIK and PRK) to your eyes, because it affects the calculations used in the selection of the power of the lens implant best suited to you.

Prior to surgery, it would help to discuss your refractive requirements with your ophthalmologist because this will also affect the selection of the most suitable artificial lens to be implanted for you. To make this selection, special tests are done usually prior to the operation day but they may also be done when you first attended the clinic or a few weeks prior to surgery. In preparation for these special test measurements, contact lens wearers must leave their contact lenses out for 1-2 weeks, if using soft contact lenses, or 2-4 weeks, if using gas permeable or hard contact lenses.

Follow all of your preoperative instructions, including not eating or drinking anything after midnight the day prior to your surgery. Arrange for family or friends to transport you home after the surgery is complete as cataract surgery does not usually require an overnight stay in hospital. You will normally be required to report several hours before the scheduled time for your surgery. An anaesthetist may work with the ophthalmologist to determine the type of sedation, where necessary. Most cataract surgery is done under local anaesthesia or with only minimal sedation without being put to sleep. To reduce sensation of the eye during cataract surgery, numbing drops or an injection around the eye may be used.

Cataract surgery will normally take approximately 20-30 minutes. It is performed while you are lying down on your back and your face partially covered by a sterile sheet. The surgeon uses a microscope with a bright light, and although you do not see the operation or the instruments used, you may be aware of a bright light, see moving shapes, and often interesting coloured lights and shadows. During the surgery, you may also notice the sensation of pressure from the various instruments used.

After leaving the operating room, you will be prescribed several eye-drops to be used for a few weeks postoperatively. Although you may notice some discomfort, most patients do not experience significant pain following surgery. You should contact your ophthalmologist or local eye casualty department urgently if you experience distorted vision, increasing blurring or decreasing vision, increasing eye redness, soreness or significant pain, an enlarging shadow in your field of vision, especially with increasing floaters or flashing lights, or a yellow / green eye discharge following cataract surgery.

Expect your operated eye to be protected with a clear plastic shield, possibly with an eye pad which you will be told when to remove yourself. The plastic shield is usually worn during sleep for about 1 week after surgery.

After surgery, the doctor or nurse will ensure you are given the postoperative instructions, the eye drops, and check that you are ready to be discharged from hospital, and this all takes about 30-60 minutes.

Avoid strenuous activity for 2 weeks & avoid heavy lifting for 4 weeks, to allow time for the self-sealing incisions, made during cataract surgery, to heal.

Use the eye drops prescribed to you as instructed – you will be shown how to clean your eye and put in the eye drops correctly. In summary, it involves tilting your head back, pulling your lower eyelid down gently, looking upwards and then, without letting the tip of the bottle touch your eye, placing the drops inside the lower lid. Avoid rubbing or touching the eye in the first 2 weeks after the surgery. Dark glasses may be worn if you find that you are sensitive to light.

You will be advised when you should return for re-assessment during the period after cataract surgery. During this period, you will be using several eye-drops which help protect against infection and inflammation. Within a few days, most people notice that their vision is better and good enough to return to work. During follow-up visits, your ophthalmologist will check for complications. Appropriate glasses may be prescribed, if needed, for optimal vision, usually about 4-6 weeks after the surgery.

Cataract surgery is one of the safest procedures available with a high rate of success. After cataract surgery, 90% of patients will have vision of 6/12 or better.

Although the pre-operative measurements usually enable the surgeon to select a lens implant which provides the desired near or distance vision, the variability of individual responses means that it is not possible to guarantee absolute accuracy, so that there may sometimes be an unexpected need for strong glasses. There is commonly a change in colour vision such that colours look brighter or bluer. Also, rare complication can occur, including one person in every 1000 going blind in that eye as a direct result of the operation, and one in 10000 losing the operated eye. There is a 1:100 risk of needing additional surgery to rectify a problem, such as the loss of all or a part of the cataract into the back of the eye. Before you sign the consent form for the surgery, your ophthalmologist will discuss the potential complications of the procedures that are unique to your eye.

The complications that can arise after cataract surgery are persistent inflammation, infection, changes in eye pressure, or swelling or detachment of the retina at the back of the eye. In rare instances, the delicate bag the lens sits in is injured (posterior capsular rupture), so that the artificial lens may need to be placed in a different location, or the artificial lens moves or malfunctions and may need to be repositioned, exchanged, or removed. All these are some of the large number of possible complications of cataract surgery but the list is not comprehensive. Many are very rare complications but even so can lead to a poor visual outcome and so close follow-up is required after cataract surgery.

The thin lens capsule may in some cases become cloudy some months or years after cataract surgery, causing a return of blurred vision. This process is called posterior capsular opacification. 1 in 10 patients require treatment with a laser procedure known as YAG laser capsulotomy, taking only minutes during an outpatient visit, to painlessly create a hole in the cloudy lens capsule and vision usually improves rapidly.