The opaque content of the crystalline lens, the eye's natural lens, is removed via an ultrasound in cataract surgery. The eye surgeon puts an intraocular lens (IOL) in its place, which is used to correct the patient's refractive error (graduation). However, in such a normal and simple surgical procedure getting the right choice of IOL for each person is fundamental. Thanks to this, many patients can live without their usual glasses and obtain a higher level of visual comfort after the surgical procedure, in addition to eliminating the cataract.
How many types of intraocular lenses exist?
We have more than 20 different types of intraocular lens at the Barraquer Ophthalmology Centre, and we place a lot of importance on choosing the right one. The main types of intraocular lenses are as follows:
Monofocal IOLs: they provide excellent quality of vision, but only at far range, as both at mid and short distance the patient will still require glasses. The final effect will be similar to a person who already has presbyopia.
Trifocal and multifocal IOLs: they allow close-up, medium and long distance vision. However, these lenses are suitable for only a few, as they require very good eye lubrication and patients with dry eyes do not tolerate them well. Dry eye is a very common pathology in older people, which is also an inconvenience for younger patients because we do not know if they are going to develop it in the future, so these lenses wouldn't be the best option. The morphology of the ocular surface is also influential: if the cornea is not homogenous then we definitely cannot opt for these lenses.
Extended depth of focus IOLs: allow correct vision in both distance and intermediate vision. In addition, in some cases we are able to use these lenses to enable the patient to see at a shorter distance, such as at a mobile phone, without the need for glasses. As they don't come with so many conditions, these lenses are a very good option that get round the limits of trifocal IOLs, since they are compatible with dry eye and less homogenous corneas.
There are also bifocal IOLs that allow the patient to see at both distance and up close, but their use is not very widespread nowadays, because they do not cover intermediate vision, where a large part of our life takes place. For example, the distance at which we look at a ticket price, a mobile phone or computer is intermediate, so this is a desirable range of vision for any patient.
Factors influencing the choice of lens
Even if we are dealing with a simpler cataract, during the preoperative phase we undertake an exhaustive examination with a wide variety of diagnostic tests to ensure that the patient will be satisfied after the operation. Each case will require a different approach and IOL depending on the following factors:
Lifestyle: the patient's habits, job and hobbies will determine the range of vision (near, intermediate and far). Their daily life is the most important part as not all lenses cover all the ranges and, even under optimum eye conditions, not all patients need the same things.
Patient's prescription: For example, an astigmatism will require a toric lens implant, a lens specially designed to correct this refractive error. Although we could operate on the cataract without correcting it, it's worth taking this opportunity to reduce the patient's dependence on glasses and give them a better quality of life. We do the same thing with myopia and hypermetropia.
Morphological characteristics of a patient's eyes, particularly the irregularities of the cornea, if any.
Tear quality and eye dryness.
Previous eye pathologies.
Existing systemic pathologies, such as diabetes.
At the end of the preoperative phase, a decision will have been made on the most appropriate lens. It’s the patient who will make the final decision along with their ophthalmologist. Carrying out this prior exhaustive study will guarantee that the patient's expectations are met.
In addition, since the surgery on the first eye and the second eye will be performed a few days apart, after the first operation there is a margin for a change in the choice of lens for the second eye. We always take all the options into account to achieve the best results.