Expert advice: Which intraocular lenses are right for me?

Intraocular lenses implanted in refractive surgery, also known as lens exchange surgery or refractive lens exchange (RLE), can allow people to reduce, or even eliminate entirely, their dependence on glasses. In this informative guide, highly-respected consultant ophthalmologist Mr Mrinal Rana shares his expert insight on the various types of intraocular lenses (IOLs) implanted in refractive surgery. The revered specialist also details what results can be expected from this type of surgery. 

Which types of lenses are used in refractive lens exchange?

A wide range of lenses can be placed within the eye, although typically the measurements that are taken of your eye prior to surgery guide the placement of an intraocular lens (IOL) of the correct power in order to achieve the appropriate vision desired in your eye after surgery.

Most people choose to have a lens placed in the eye that allows them clear distance vision without glasses, but, with the placement of a standard monofocal IOL, patients would almost certainly require reading glasses for close work. With modern laser eye measuring techniques, the overwhelming majority of patients (at least eighty-five per cent) achieve their ‘refractive’ goal i.e. the desired spectacle prescription, if any, after surgery.

There are three main kinds of premium intraocular lenses (IOLs) which may be suitable for you and will increase the chance of you not needing glasses after surgery:

• Toric IOLs, which allow the correction of pre-existing astigmatism
• Multifocal IOLs, which are similar in concept to bifocal glasses or especially multifocal contact lenses, except that the lens is within the eye. The goal of these lenses is to allow the ability to see both distance (e.g. driving) and near (e.g. reading) without glasses
• Toric multifocal IOLs, which combine the advantages of both these types of lenses. It is a more bespoke lens, placed inside the eye to correct a patient’s astigmatism and at the same time, reducing the patient’s short- or long-sightedness.

What types of results can be achieved with refractive surgery?

After surgery, the chance of needing glasses for distance is greatly reduced, although without the simultaneous placement of a multifocal component of the lens (toric multifocal), patients should still expect to need reading glasses. Cataract or RLE surgery in patients with marked astigmatism using standard, non-toric IOLs usually leads to improvements in unaided vision, but patients should not expect that their final distance or near vision will be clear without glasses.

It is not always possible to use a toric lens, even if an individual has significant astigmatism. Reasons for this include inconsistent scan data, poor corneal surfaces (e.g. very dry), irregular astigmatism and small pupils, which preclude accurate placement of the lenses.

Multifocal lenses are specially designed to create (at least) two images simultaneously, one of which is in focus for near sight and the other for distance. The individual’s brain decides which image will be ‘used’, depending on what is being looked at. With such lenses, about eighty-five per cent of people achieve day-to-day spectacle independence, meaning that typically they can both drive and read as needed in daily life, such as a restaurant menu, without glasses. For more prolonged reading, however, many patients still choose to wear reading glasses.

As multifocal lenses split the light entering the eye into at least two images, there is by definition a compromise in the quality of vision achieved. Although around eighty-five to ninety per cent of patients are spectacle-independent after surgery, the distance and near vision achieved is unlikely to be as impressive as if a standard, monofocal lens (with reading glasses) had been used - the upside, of course, being the lack of a need for near spectacles.

Multifocal lenses are probably unsuitable for patients with optically demanding hobbies and occupations, such as astronomers or photographers, although the golfer Gary Player has notably done very well after such surgery! In the dark – and occasionally even the light - some patients do complain of haloes or glare around lights and multifocal lenses are thus unsuitable for occupational night drivers. In addition, people with relatively low degrees of short-sightedness are not great candidates for these lenses, as they are used to an excellent quality of unaided near vision.

Although it can be difficult to determine in advance who may be dissatisfied with the quality of vision achieved with multifocal lenses, dissatisfaction may be more common in people with ‘type A’ or detail-orientated personalities, as well as those with good unaided distance vision already.

Toric multifocal lenses combine the benefits of both toric and multifocal lenses, simultaneously improving astigmatism and aiming to achieve spectacle-independence for distance and near sight. The premium lenses discussed above are not necessarily better than the monofocal lenses used in ‘standard’ lens RLE or cataract surgery. Your surgeon will discuss with you in detail which lens choice we believe will be the best choice for you.

All premium lenses require accurate placement within the capsular bag of the eye and, unlike standard lenses, there is the possibility of:

• migration of the lens in the postoperative period, which may potentially require a repositioning procedure (approximately 1:100 patients)
• late migration of the lens, with potential reduction in vision
• not being able to use a premium lens as planned during a procedure, in the unlikely event of a surgical complication making the placement of such a lens unsafe 

In this latter situation, patients must be aware that there is a chance that their vision will not be corrected to the extent that they had hoped. For example, no reading vision without glasses and/or a residual requirement for spectacles for distance, if astigmatism cannot be corrected.

If you are considering refractive lens exchange surgery and would like to discuss your options further, you can schedule a consultation with Mr Rana by visiting his Top Doctor’s profile.