Intraocular lenses for cataract surgery: what are my options?

There are a whole host of intraocular lenses to choose from, but how do you know which is the right choice for you? Renowned consultant ophthalmologist Mr Shahram Kashani discusses all the options available on the market and how to choose the best option based on your needs.

What are the different types of intraocular lenses (IOLs) available for cataract surgery?

There are 4 main types of intraocular lenses:

Monofocal lenses: These aim to correct vision and minimise dependence for glasses at a single focal point. Monofocal lenses can only correct farsightedness (hyperopia) or short-sightedness (myopia) but never both at the same time. The majority of people have their focal point set for distant vision, which would mean they will need glasses for intermediate and near vision.

Toric monofocal lenses

Monofocal lenses can achieve the best possible unaided vision for the target focal point, provided that the shape of the cornea is spherical. This means that the curvature of the eye is similar in all directions. Some eyes are shaped more like a rugby ball and so a simple monofocal lens cannot address the asymmetrical shape of the cornea. In this situation a premium monofocal toric lens may be an option to reduce the oblongness (astigmatism) of the eye. You will still need glasses for intermediate and near vision, if the post-op target was to correct distant vision.

Extended depth of focus lenses (EDOF)

A premium lens which works by creating a single elongated focal point when light enters the eye and enables you to focus at a continuous range of distance (intermediate and near vision) unaided. EDOF lenses tend to cause less glare/halo effect when compared to multifocal trifocal lenses, however, near vision can be less clear when compared to a multifocal lens and you may need glasses to manage some tasks at near vision. These lenses are also available in the toric range, if astigmatism correction is required.

Multifocal trifocal lenses:

A premium lens which aims to correct your vision and reduce your dependence on glasses for multiple distances, far, intermediate and near vision. They work by splitting light that enters your eye in more than one focal point, allowing you to switch between far, intermediate and near vision. Unfortunately, there are potential side effects (e.g halos, glare, reduced contrast). These must be explored in detail at your consultation, to ensure that this lens will suit your needs. They are also available in toric range, if astigmatism needs to be corrected.

How do I decide which type of IOL is best for me?

Choosing an IOL can be challenging. Once a lens has been placed inside the eye, it is surgically very difficult to replace the lens. Various factors need to be explored at the time of your consultation to ensure that the chosen lens is best for you. The decision for choosing a premium lens rests upon your desire to reduce dependence on glasses after surgery for various tasks.

You need to consider work, life style and hobbies when deciding on which lens is best suited to your needs. The desire to minimise your dependence on glasses for various tasks must to be balanced against various potential side effects of some types of lenses such as reduced contrast sensitivity, glare, halos and star bursts.

What are the advantages and disadvantages of monofocal vs. multifocal IOLs?

Cataract surgery aims to correct your best corrected vision, and with advancing technology, intraocular lenses also aim to minimise your dependence on glasses for various focal points. In the case of a monofocal lens, if there is no astigmatism, you will still require glasses for intermediate and near vision, if you have chosen a lens to correct your vision for distance. This is the main disadvantage of a monofcoal lens, however, there is minimal risk with glare, halos, star burst or issues with contrast. It is also ideal if you have co-existing ocular conditions such as macular degeneration or glaucoma.

While a multifocal trifocal lens can minimise your dependence on glasses for near, intermediate and distant vision, a significant portion of patients can initially experience glare, halos, star burst and reduced contrast sensitivity. In the majority of cases, these symptoms reside as patients neuro adapt, but a small group of patients will continue to experience these symptoms, often in the evening, and may experience difficulty driving at night.

EDOF lenses significantly reduce the risk of glare, halos and contrast sensitivity issues post operatively but the patient may still need some correction for reading small print, while toric lenses correct astigmatism in the eye, but contain a small risk of lens rotation with recurrence of astigmatism.

Inaccuracies in pre-operative measurements, individual differences in wound healing and variations in formula calculations can also contribute to a sub optimal outcome. Fortunately, these occurrences are rare.

Before undergoing surgery, patients will require a very careful assessment of their symptoms, desires and expectations, as well as a detailed assessment of various diagnostics, in order to ensure they have the correct lens that meets all their needs.

What if I have any other eye conditions?

The presence of other ocular pathology such as glaucoma or macular degeneration can affect the prognosis of vision. If you have a significant ocular disease, a premium lens such as an EDOF lens or a multifocal  lens it is not advisable.   

How long does it take to recover from cataract surgery with different types of IOLs?

In general, recovery after cataract surgery varies between patients but we expect full recovery after 4 weeks, in particular with a monofocal or a monofocal toric lens. Premium multifocal lenses may take longer to neuro adapt, therefore recovery in that sense can be more prolonged, especially with regards to resolution of symptoms such as  glare, halos and starbursts. These symptoms will persists in a small proportion of patients with multifocal trifocal and less so with EDOF lenses.

If you in the process of choosing intraocular lenses and would like to discuss this further with Mr Kashani, do not hesitate to do so by booking an appointment through his Top Doctors profile today.