The lens approach – CLE and multifocal lenses

Sep 09, 2010

Clear lens extraction can be offered to ametropic patients in their presbyopic age as a refractive procedure that can virtually eliminate any need for optical correction.

“Clear lens extraction is currently a safer procedure than years ago,” said Italy's Dr Roberto Bellucci, speaking at the European Society of Cataract and Refractive Surgeons ESCRS meeting in Paris, “because of the improvement in the techniques as well as in the outcome. Therefore it can be offered to ametropic patients in their presbyopic age as a refractive procedure that can virtually eliminate any need of optical correction.”

When using multifocal lenses, Dr Belluci said it should be remembered that they produce two images of any observed object. Under the best conditions, one image will be in focus and the second image will be defocussed by the dioptric add for near vision. The two images confound each other, reducing contrast sensitivity and to some extent visual acuity. For this reason the least satisfied patients are the emmetropes and the low myopes, who in addition often complain about intermediate vision, while high ametropes are better addressed. However, care should be taken to detect amblyopia and poor macular function in the preoperative, as those will deeply decrease patient satisfaction with multifocal lenses. A trial with multifocal contact lenses is always advisable.

Personal experience reported here comprises 85 patients implanted bilaterally with three types of diffractive multifocal IOLs: Alcon ReSTOR, AMO Tecnis Multifocal and Zeiss Acri.Lisa. Every patient removed spectacles completely, however 22 eyes had LASIK to correct for residual refractive errors. Eyes with the Acri.Lisa Toric IOL showed nice correction of the pre-operative astigmatism. Most common causes of dissatisfaction were: poor intermediate visual acuity (2), poor distance visual acuity (4), poor near visual acuity (5), poor contrast sensitivity (1). One patient required IOL exchange to monofocal.

The optical quality of the operated eyes as evaluated by Hartmann-Shack and Double-Pass aberrometry was satisfying. In a subgroup of Acri.Lisa eyes the contrast sensitivity measured at the near focus was lower than the contrast sensitivity at the distance focus. As this lens has asymmetric light distribution favoring the distance focus, we concluded that with this type of lens the near vision can be improved by correcting for near the distance power, like we do with monofocal lenses.

In conclusion Dr Belluci said that he believes that CLE plus multifocal IOL implant is a safe and effective approach to solve presbyopia problems in hyperopes and medium myopes, provided the two eyes have good vision. At the moment, he would not recommend this procedure in emmetropes or low myopes. Multifocal IOL selection should consider the advantages of asymmetric light distribution, and should take into account the early good results recently reported with zonal refractive multifocal IOLs.

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