When we were much younger many of us enjoyed clear vision for everyday tasks, hobbies and pursuits that were visually demanding. Even if we needed spectacles as a child, we had ample accommodation to allow for instant changes of focus on objects at any distance. We did not think about it, we just did it.
In the world of cataract surgery, we have been implanting lenses into eyes for at least 40 years. As we use applied optics to solve refractive aims, the change in technology has been massive and the range of lens options are now so diverse. But how close are we to achieving the sight of our earlier days?
The standard option for our NHS patients is to use a monofocal intraocular lens (IOL) and to aim for a refractive outcome close to plano. This has been the default for years and if the patient has minimal corneal astigmatism, the results can allow spectacle free distance vision for many. Some myopes prefer good unaided reading vision and this is also very straightforward – just put -2.5D into the calculator and an IOL is selected for this aim. Monovision options can be used with IOLs in cases where this is already tried and tested with contact lenses.
This all sounds familiar, I hear you say. However, we still need to remember this is surgery, and some of the rare complications of surgery, can play havoc with refractive outcomes. An unstable capsule or a wound leak requiring corneal sutures can lead to demanding situations where an IOL may have to be implanted later or further astigmatism management is needed. We must remember that we cannot give a 100% guarantee for surgery and patients need to be reminded of this.
Even when surgery is uncomplicated there is a range of refractive outcomes related to IOL choice. You know very well that a change of +/-0.5D to a prescription is noticeable but even the best IOL formulae only achieve the refractive aim within +/-0.5D in about 75% of cases. This stems from assumptions about the eye’s optics, not least in estimating the position of the IOL on the visual axis.
So, to summarise, while our NHS patients do get a good deal with the chance of simplified refractive outcomes, there is still plenty to do in terms of optical correction to allow them to reach their preferred lifestyle options.
Beyond the NHS, there has been a substantial change in refractive lens technology over the past 20 years. Patients are often keen to understand their options for lenses that extend depth of focus (EDOF) from distance to nearer vision or alternatively for multifocal IOLs that create separate focal points on the fovea for distance, intermediate and near vision.
Surgeons work hard with these patients to minimise refractive error and to achieve excellent binocular vision. Patients usually experience a rapid change in vision after the second eye has surgery and can use their new vision to pursue their preferred activities, largely spectacle free.
Wise surgeons always counsel patients that these IOL options are not there to enable them to throw away spectacles but to permit more activities without them. Some may require a reading add and others may need a minimal correction for distance at times, for example when night driving.
There may well be good medical reasons not to adopt these lenses such as early age-related macular degeneration or dry eye and this should be noted early in any pre-op consultation. However, confounding symptoms after this type of surgery, such as glare or starburst, are much less common in recent years and these are not necessarily a reason to avoid surgery altogether.
Added to the menu is the option of a toric correction – these IOLs can be monofocal, EDOF or multifocal and careful placement of the IOL using software guidance can negate corneal astigmatism in over 90% of cases. The role of the optometrist in referring and
recommending options to patients cannot be underestimated.
As their regular advisor, you are in the unique position to influence this conversation and as a surgeon, I want to hear from you about what your patients prefer. Your patients’ lifestyle characteristics are really important and failure to note a visually demanding occupation or hobby can lead to much frustration.
Night drivers need the clearest distance vision, orchestra conductors need to read the score as well as their musical colleagues, tennis players want to see the ball – I could go on. Returning our patients to brilliant vision is a really great thing and surgeons are so enthusiastic about it. While we cannot create an exact match for the clarity and range that a child has, we can offer some brilliant solutions. Please tell us what your patients want – we will deliver.
- Nigel Kirkpatrick is a consultant ophthalmologist and medical director of Newmedica.