The trifocals are a type of multifocal lenses that are designed to get a good focus on both distant and near vision, as well as intermediate. Unlike conventional multifocal lenses, or only allow focus from far and near, or focus far and intermediate vision, these trifocals allow good vision at all three distances. This is important because in today's life we are becoming more dependent on mobile screens and whose focus is between 60-80 centimeters (intermediate distance).
Who can resort to trifocals?
The ideal patients would cataracts and presbyopia patients who wish to do without glasses in most thereof, preferably farsighted daily activities, but also can be used with few diopters myopic corneal astigmatism and less than 1-1.25 diopters.
They must be patient to understand the limitations of this type of lenses (ie, good vision for all distances, but not excellent).
On the other hand, these types of lenses are not advised in patients with some type of concomitant ocular pathology as maculopathy, advanced glaucoma, retinopathy, corneal scars ...
Differences between trifocals and multifocal intraocular lenses
The main difference is that most multifocal lenses provide good distance vision and good near vision or intermediate, but not for the three distances. Thus, there are multifocal lenses for distance and near (but without intermediate vision) and others for distant vision and intermediate vision (but not for near vision).
Risks of trifocals
The trifocals, as most multifocal lenses can cause halos and night glare. These halos do not disappear but a very high percentage of patients are well used to them and do not detect. Another problem is the loss of contrast sensitivity, inherent in all such trifocal and multifocal lenses, which manifests itself in reduced visual acuity in low light situations. This type of lenses, finally, are poorly tolerated if more postoperative refractive error of 0.75 diopters is; For this reason, all patients will be operated on trifocals are warned of the possibility of retouching refractive (LASIK or PRK) after surgery if this refractive defect occurs. Fortunately, if the patient is well selected and calculations are correct, this possibility refractive retouching is less than 5-8% of cases.
For more information contact a specialist in ophthalmology .