Our ophthalmologists are now able to offer you the next generation of multifocal intraocular lenses (IOL’s) – the trifocal. This implant gives patients a better chance to enjoy clear vision at all distances with maintained contrast sensitivity and lower visual disturbance.
The older generation multifocal lenses offer clear distance and near vision, however they are least clear for intermediate vision and can result in glare and haloes especially with night driving. The trifocal implant has the advantage of offering clear intermediate as well as distance and near vision with minimal glare and haloes at night.
Monofocal intraocular lenses have been designed in order to offer an excellent quality of vision for long distance. They allow us to correct refractive errors previous to the cataract surgery such as myopia and hyperopia. So if the patient had myopia or hyperopia before the surgery we can correct it with this lenses even if the magnitude of these errors were very high. After the surgery the patient will have an excellent vision for long distance. For near vision and intermediate the patient could need glasses. Monovision may be employed to allow for good distance and reading vision without glasses but at the loss of some depth perception. If the patient has significant astigmatism, the patient must adjust his or her expectations to allow for the blurring from the astigmatism, and the improved vision that correcting the astigmatism with glasses will bring.
The premium IOLs are all specifically designed to reduce a patient’s need for glasses. Currently available premium IOLs include the toric, the multifocal, the toric multifocal, and the accommodative IOLs. Now we have the newest, the Trifocal IOLs. Each IOL has its own strengths and weaknesses. One “weakness” that they all have in common is that they all are specifically designed to reduce the patient’s dependency on glasses. Third-party payers generally look upon this goal as “cosmetic,” and any extra charges associated with these IOLs will fall directly on the patient. Unfortunately, no IOL can guarantee that the patient will be entirely free of glasses. Therefore, it is best to inform the patients that premium IOLs will reduce, but not eliminate, their need for glasses.
-Toric IOLs. Toric IOLs are best for patients with significant astigmatism who desire less dependency on glasses. Because they also correct patients’ astigmatism, toric IOLs will allow improved distance vision without glasses or improved reading vision without glasses.
The weakness that toric IOLs share with standard monofocal IOLs is that they are monofocal, allowing either distance vision or reading vision, but not both distance and reading without glasses (unless monovision is employed). Toric IOLs work best with symmetric “bow-tie” astigmatism, but they do not correct irregular astigmatism from corneal scarring, keratoconus, or other corneal abnormalities. The orientation of the IOL within the eye is critical to addressing the astigmatism. If the lens is not oriented in-line with the astigmatism, the toric IOL may not correct as much astigmatism as it should.
-Multifocal IOLs. Multifocal IOLs use either diffractive or refractive techniques to allow for 2 focal points: one for distance and one for reading. Multifocal IOLs are best for patients who desire both good distance and good reading vision without glasses.
One weakness is that they currently do not correct astigmatism; therefore, patients with significant astigmatism after the surgery may not have as good vision as they desire. In this case, now its available the toric multifocal IOL. Other weakness is that patients usually experience halos or glare around light sources at night. This is usually mild and tolerable for most patients. A third weakness is that although currently available multifocal IOLs may allow for acceptable intermediate vision in most patients, some patients find that their intermediate vision is not as good as they would like, affecting intermediate range tasks, such as reading on a computer or seeing prices on store shelves.
With refractive multifocal IOLs, smaller pupil sizes may limit the amount of light passing through the different refractive rings, thus limiting the multifocal effect of the IOL. Furthermore, given the loss of contrast inherent in a multifocal IOL, they generally do not work well in patients with corneal disease, macular disease, glaucoma, or other ocular pathology. Patients with such processes should be guided to other IOLs.
-Accommodative IOLs. Accommodative IOLs use materials and design techniques that allow the IOL to flex via contraction of the ciliary body, thus shifting the focal point from distance to intermediate, and from intermediate to near. Accommodative IOLs are best for patients whose goals include good uncorrected distance and intermediate vision, but who find it acceptable to wear glasses for extended periods of reading.
Generally, most patients are able to achieve good uncorrected distance and intermediate vision for extended periods, but sustained reading for periods longer than 20 minutes requires reading glasses. Modified monovision may be used to allow for increased reading functionality. Also, these lenses do not correct astigmatism, so patients with increasing astigmatism get correspondingly worse uncorrected visual acuity. Because accommodative IOLs are monofocal lenses, less glare is experienced than with multifocal IOLs. The risk of halos or glare should not be increased much when compared with the standard monofocal IOL. However, the smaller optic size (eg, 5 mm for Bausch & Lomb Crystalens®, vs 6 mm for most standard monofocal IOLs) > may allow more peripheral light rays to go around the optic in scotopic conditions. They must flex in order to provide the accommodative function. If the IOL does not flex correctly (eg, due to ciliary body dysfunction, capsular contracture, and zonular dialysis/dehiscence), the patient essentially has the equivalent of a standard monofocal IOL, which relies solely on optics to function.
-Presbyopia-correcting intraocular lens (Trifocal IOLs). These new lenses allow 3 focal points: near (40cm), intermediate (60cm) and long distance. The AcrySof IQ PanOptix trifocal IOL is indicated for adult patients with and without presbyopia undergoing cataract surgery who desire near, intermediate and distance vision with increased spectacle independence.