A lot has been written about the different types of multifocal IOLs (intraocular lenses), but not many people know that there is a significant difference between each of these lenses. In other words, not all multifocal IOLs are equal. It is important to understand that, while a few multifocal IOLs make use of refractive optics, others utilize diffractive optics. Also, each optic variety has a different visual characteristic; hence patients may feel that they enjoy better vision when they choose a specific lens type over the others.
Cataract surgeons explain that most concerns regarding multifocal IOLs are related to right product selection. Each patient has his/her own visual preferences and needs and so some patients might be better off with a specific variety of IOL and not the other. In this scenario, it is critical for doctors to understand the working of multifocal lenses and choose the right IOL for the right patient.
Let’s take the example of the ‘Comfort Lens’. This refractive lens boasts of excellent light transmission. It provides +1.5 D to enhance intermediate vision. The Symphony IOLs, on the other hand, come with a diffractive rear surface which creates a consistent focus with the addition of approximately +1.78 D. The combination of a refractive front surface and diffractive rear surface helps reduce distortion in vision and leads to better contrast sensitivity. Both lens varieties are quite similar in function and safety.
Lens Selection for Patients
Experienced eye doctors go about lens selection for each patient by showing them all different ranges of focus that are available. Another important aspect of selection is asking about the lifestyle, jobs, hobbies and other family life of the patient. Stimulation software is often used for showing the patients the effects of glare and halo in four distinct categories-severe, moderate, mild and zero. This way a patient would be able to understand the effects of different compromises after surgery. Patients need to identify their priorities e.g. ability to read smaller print without eyeglasses or the avoidance of glare and halos. Doctors inform that case studies show less trouble in the case of refractive IOLs, especially for patients who wish to avoid glare and halos. In some cases, the multifocal lens implants are simply not the correct choice for a given patient. In that case, standard monofocal lenses may be used, as long as the patient understands that they will be very dependent on glasses after surgery.