Blue-light filtering intraocular lenses (IOLS) for protecting macular health

Background: An intraocular lens (IOL) is a synthetic lens that is surgically implanted within the eye following removal of the crystalline lens, during cataract surgery. While all modern IOLs attenuate the transmission of ultra‐violet (UV) light, some IOLs, called blue‐blocking or blue‐light filtering IOLs, also reduce short‐wavelength visible light transmission. The rationale for blue‐light filtering IOLs derives primarily from cell culture and animal studies, which suggest that short‐wavelength visible light can induce retinal photoxicity. Blue‐light filtering IOLs have been suggested to impart retinal protection and potentially prevent the development and progression of age‐related macular degeneration (AMD). We sought to investigate the evidence relating to these suggested benefits of blue‐light filtering IOLs, and to consider any potential adverse effects. Objectives: To assess the effects of blue‐light filtering IOLs compared with non‐blue‐light filtering IOLs, with respect to providing protection to macular health and function. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 9); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the ICTRP. The date of the search was 25 October 2017. Selection criteria: We included randomised controlled trials (RCTs), involving adult participants undergoing cataract extraction, where a blue‐light filtering IOL was compared with an equivalent non‐blue‐light filtering IOL. Data collection and analysis: The prespecified primary outcome was the change in distance best‐corrected visual acuity (BCVA), as a continuous outcome, between baseline and 12 months of follow‐up. Prespecified secondary outcomes included postoperative contrast sensitivity, colour discrimination, macular pigment optical density (MPOD), proportion of eyes with a pathological finding at the macula (including, but not limited to the development or progression of AMD, or both), daytime alertness, reaction time and patient satisfaction. We evaluated findings related to ocular and systemic adverse effects. Two review authors independently screened abstracts and full‐text articles, extracted data from eligible RCTs and judged the risk of bias using the Cochrane tool. We reached a consensus on any disagreements by discussion. Where appropriate, we pooled data relating to outcomes and used random‐effects or fixed‐effect models for the meta‐analyses. We summarised the overall certainty of the evidence using GRADE.