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Various models of mutlifocal IOLs are currently available that enable patients to see at two focal points (distant and near). These lenses have demonstrated good safety, efficacy and predictability in correcting ametropia and presbyopia after phaco surgery although some visual side effects have been observed.
Different models of multifocal IOLs are currently available which are based on either refractive, segmented or diffractive optical designs to focus the light entering the pupil at different distances.1 Diffractive multifocal IOLs are based on a diffractive grating on the optic of the lens that divides light into two focal planes to get focused images of distant and near objects over the retina,1 allowing spectacle independence in many patients.2
These IOLs have demonstrated good safety, efficacy and predictability in correcting ametropia and presbyopia after phacoemulsification surgery for crystalline lens extraction, although some visual side effects, such as halos, glare or starburst, have been reported with some specific models.3
There has been some data recently published on the Tecnis ZMB00 multifocal IOL, but the patients were not all binocularly implanted and advanced measures of visual function such as defocus curves and reading speed were not assessed.5,6 Recently, five different European centres conducted a prospective study to assess functional visual outcome in patients bilaterally implanted with the Tecnis ZMB00 IOL and to determine the drivers of patient satisfaction after the implantation of this new concept of IOL.7
The European multicentre study
A total of 104 eyes of 52 patients scheduled for bilateral phacoemulsification cataract surgery with implantation of the diffractive multifocal IOL Tecnis ZMB00 were enrolled in a multicentre European study conducted across five European sites. Exclusion criteria included known pathology that may reduce visual acuity to below 20/25 after surgery (such as macular degeneration, cystoid macular oedema, proliferative diabetic retinopathy, etc.), use of systemic or ocular medications that may affect vision, residual astigmatism likely to be >1.0 D after surgery, previous ocular trauma and ocular/refractive surgery or inflammation.
All surgeries were performed under topical anaesthesia by experienced surgeons using the same standard sutureless microincision phacoemulsification technique, with implantation of the IOL into the capsular bag using an advanced injection system (One Series ULTRA INSERTION System, Abbott Medical Optics). All patients were evaluated at 4–6 months after surgery, with examination of the fundus and anterior segment to determine the presence or absence of any medical or IOL findings or complications, manifest spherocylindrical subjective refraction, uncorrected and best corrected visual acuity under photopic and mesopic lighting conditions (ETDRS test, 4 m), pupil size using an infrared pupillometer, binocular defocus curve testing in photopic conditions, binocular reading acuity, critical print size and reading speed using the Radner reading chart at 40 cm under photopic and mesopic conditions, and assessment of visual disturbances and spectacle independence with a self-developed questionnaire. This questionnaire asked about optical visual symptoms (halos and starbursts), use of visual correction (rated on a 5-point scale) and visual satisfaction (rated on a 5-point scale).