Intraocular lenses are prostheses that are inserted inside the eye to correct graduation defects. As Dr. Humberto Carreras, medical director of Eurocanarias Oftalmológica, explains, all lenses are made of biocompatible materials and last a lifetime.
Types of intraocular lenses
There are two main groups of intraocular lenses. One is phakic lenses, which are those that are inserted without the need to remove the crystalline lens. On the other hand, there are pseudophakic lenses, i.e., those that are implanted when the crystalline lens is removed, for example in cataract surgery.
Within each group there are different models, so we can find monofocal pseudophakic lenses, which correct distance prescription defects, and other multifocal lenses, used to correct both distance and near prescription defects.
When should the crystalline lens be removed when implanting an intraocular lens?
The crystalline lens is removed when we find a cataract or an alteration, either due to a loss of transparency or when we find advanced presbyopia with a deteriorated lens.
If a young patient of 25 years of age with myopia comes to us, we perform a preliminary study. If the myopia is not high and the cornea is thick, corneal surgery is performed. But if there are many diopters or the cornea is very thin, we implant a lens without removing the crystalline lens.
The same assumption in a person of 55 years, probably, the lens is not so healthy, may have loss of focusing ability (eyestrain), which originates in the lens and may or may not have loss of transparency, ie, a beginning of cataract. In this case, we usually remove the crystalline lens and replace it with a pseudophakic intraocular lens, probably multifocal to correct the distance and near graduation.
The study prior to surgery
To determine the patient’s suitability and which is the best option according to the prescription and characteristics of the eye, a specialist in Ophthalmology performs a preliminary study.
In the previous study, the depth of the anterior chamber is measured, which must have certain limits to ensure that the intraocular lens fits in the eye without altering the other anatomical structures.
Patients suitable for phakic lens implantation
Phakic intraocular lenses are indicated in patients with high prescription, generally hyperopia, myopia or astigmatism. The goal is to eliminate dependence on glasses but surgery on the cornea is not possible, either because it is too dioptric or because the cornea is not thick enough.
ICL lenses in patients with high prescriptions
The intraocular lens is a kind of contact lens that is implanted inside the eye, the most common are those that are placed between the pupil and the crystalline lens, which are called ICL.
These are implanted in an operation that lasts 10 minutes and allows correcting the high graduation in myopia, hyperopia or astigmatism. In addition, it also allows to obtain a very good quality of vision, a very fast recovery and all through a surgery that is performed on an outpatient basis.
There are two types of ICLs:
- Spherical: especially indicated for patients with myopia or hyperopia.
- Toric: used in patients who, in addition to myopia or hyperopia, have astigmatism.
This lens is indicated for young patients with a prescription defect that cannot be corrected with corneal surgery, either because the cornea is thin or because the number of diopters is high. In this case, always making a previous study, we choose, if there is room for an intraocular lens, an ICL type.
Correcting presbyopia and refractive defects simultaneously
There are new models of intraocular lenses called IPCL. These lenses can correct presbyopia in patients with near vision problems, but in whom it is not indicated to remove the crystalline lens. This corrects both distance and near vision defects.