Treatment of Cataracts

In general, cataracts do not entail any risk for the patient. There is no need to perform surgery if the patient does not suffer any visual impairment in their everyday life or does not wish to undergo surgery despite having vision problems. However, the potential risks associated with surgery and the reasonable likelihood of improvement will be assessed if the cataract progresses to such a degree that it affects the patient’s lifestyle.

Non-drug therapy

Apart from surgery, there are currently no other treatments that have proven effective at preventing or treating cataracts, apart from avoiding the known risk factors. Therefore, following a healthy diet, physical exercise, reducing smoking and wearing caps, hats or sunglasses that filter out UVB radiation to protect from ultraviolet light are reasonable measures to reduce the incidence of cataracts in the general population. The prevention and treatment of diseases such as diabetes, high blood pressure, obesity and high cholesterol levels (hypercholesterolemia) can also help lower the risk of developing cataracts. Notwithstanding, protective eyewear is recommended for high risk activities, especially for patients who only have good vision in one eye, due to the risk of sustaining a cataract caused by blunt or penetrating trauma.

Surgical treatment

The principal technique for cataract surgery in the developed world is phacoemulsification with foldable intraocular lens implant.

This technique consists of making two small incisions in the cornea (the transparent, dome-shaped tissue at the front of the eye), one just over 2 mm long, while the second measures roughly 1 mm. A transparent viscous gel is injected into the front portion of the eye to protect its different layers and preserve its shape while working through the open incisions.

The surgeon then makes a round opening in the natural sac, known as the lens capsule, which holds the cataract in place. The capsule is separated from the rest of the cataract with a saline solution. At this point, the capsular sac is open and the cataract moves around freely within the sac. A special, pen-sized device (a phacoemulsification probe) is used to fragment the cataract into small pieces, like a pneumatic hammer, which are then aspirated out of the eye. This technique is called phacoemulsification. Once the cataract has been fragmented and removed, another viscous gel is injected into the capsular sac to open it up and make room for the new artificial intraocular lens. This lens is folded up when implanted in the capsular sac through the corneal incision, then it is slowly opened and set in position. Finally, the viscous material is removed from inside the eye by aspiration and the two corneal incisions are inspected and often closed without the need for stitches.

Occasionally, another type of surgery called extracapsular lens extraction is a better option, which requires an incision of up to 8 mm. It is usually reserved for complicated cataracts, for example, very hard cataracts or cases that present a greater risk of a complication called corneal decompensation.

Intraocular lenses (IOLs)

A cataract is opacity in the lens, which is the part of the eye that focuses images on the retina. Under normal conditions, the lens can change its curvature to focus objects at different distances. Therefore, young people without any refractive errors in their vision can see well at all distances without the need for glasses. As we get older, however, the lens ages, loses its ability to change its curvature and starts to produce poor near vision, which is known as presbyopia or tired eyes.

Another change the lens undergoes with the onset of cataracts is a loss of its transparency. This causes a reduction in vision and the ability to make out details.

To treat cataracts, the area of the lens that has lost its transparency must be removed and replaced with a new transparent intraocular lens (IOL), which will remain in the patient’s eye forever.

Before IOLs were developed, the only vision correction options after cataract surgery were to wear hard contact lenses or very thick glasses. The first IOL was implanted in London in 1949, and since then cataract surgery and IOLs have not stopped evolving and improving.

IOLs are made of inert (non-reactive) materials such as silicone or acrylic. In the same way as the eye’s natural lens, intraocular lenses allow light to pass through them and focus the rays as images on the retina.

Monofocal, toric and multifocal IOLs

Most intraocular lens implants involve the insertion of monofocal IOLs, meaning they offer “one point of focus”. These lenses provide just a single type of clear, focused vision. This could be clear vision at a near or far distance, but not both. Most patients who select a monofocal lens want to have good far vision and then use glasses for near vision activities such as reading, sewing or looking at a computer screen. Meanwhile other people prefer to have good near vision and only wear glasses for far vision. Most of these patients have myopia.

It is also possible to plan surgery so that one eye is optimised for far vision and the other for near vision to minimise the need for glasses. This is called monovision. Patients who select this option sometimes find it hard to get used to because they only use one eye at a time, either for near or far vision. You may even need to wear glasses for some activities such as looking at a computer or driving at night. It is not always the best option and should only be considered after discussing it with your ophthalmologist.

Toric intraocular lenses are another type which may be implanted to correct a patient’s astigmatism. Toric lenses are optically more complex than monofocal lenses. The surgical procedure is basically the same; however, when a toric lens is implanted it must be carefully rotated until it takes up a predetermined position specific to each patient and the axis of their astigmatism. Monofocal lenses do not need to be placed with such a high degree of accuracy.

Multifocal intraocular lenses have special technical characteristics, so they can provide more than one focal point, i.e., they allow the eye to focus on objects located at different distances, whether far, intermediate or near. Therefore, patients implanted with a multifocal lens can often see objects over a range of distances without using glasses, or they rely on glasses much less than patients who have received a monofocal lens.

Both toric and multifocal IOLs require a more complicated optical calculation than the one applied to monofocal lenses and therefore entail the use of sophisticated instruments and professionals with expertise in interpreting the data obtained. Furthermore, there are several types of multifocal lens and the choice between them depends on factors such as the patient’s age, prior refractive error, their regular activities and occupation.