Trends in prevalence of blindness and distance and near vision impairment over 30 years: an analysis for the Global Burden of Disease Study

Published Online December 1, 2020Background: To contribute to the WHO initiative, VISION 2020: The Right to Sight, an assessment of global vision impairment in 2020 and temporal change is needed. We aimed to extensively update estimates of global vision loss burden, presenting estimates for 2020, temporal change over three decades between 1990–2020, and forecasts for 2050. Methods: We did a systematic review and meta-analysis of population-based surveys of eye disease from January, 1980, to October, 2018. Only studies with samples representative of the population and with clearly defined visual acuity testing protocols were included. We fitted hierarchical models to estimate 2020 prevalence (with 95% uncertainty intervals [UIs]) of mild vision impairment (presenting visual acuity ≥6/18 and <6/12), moderate and severe vision impairment (<6/18 to 3/60), and blindness (<3/60 or less than 10° visual field around central fixation); and vision impairment from uncorrected presbyopia (presenting near vision <N6 or <N8 at 40 cm where best-corrected distance visual acuity is ≥6/12). We forecast estimates of vision loss up to 2050. Findings: In 2020, an estimated 43·3 million (95% UI 37·6–48·4) people were blind, of whom 23·9 million (55%; 20·8–26·8) were estimated to be female. We estimated 295 million (267–325) people to have moderate and severe vision impairment, of whom 163 million (55%; 147–179) were female; 258 million (233–285) to have mild vision impairment, of whom 142 million (55%; 128–157) were female; and 510 million (371–667) to have visual impairment from uncorrected presbyopia, of whom 280 million (55%; 205–365) were female. Globally, between 1990 and 2020, among adults aged 50 years or older, age-standardised prevalence of blindness decreased by 28·5% (–29·4 to –27·7) and prevalence of mild vision impairment decreased slightly (–0·3%, –0·8 to –0·2), whereas prevalence of moderate and severe vision impairment increased slightly (2·5%, 1·9 to 3·2; insufficient data were available to calculate this statistic for vision impairment from uncorrected presbyopia). In this period, the number of people who were blind increased by 50·6% (47·8 to 53·4) and the number with moderate and severe vision impairment increased by 91·7% (87·6 to 95·8). By 2050, we predict 61·0 million (52·9 to 69·3) people will be blind, 474 million (428 to 518) will have moderate and severe vision impairment, 360 million (322 to 400) will have mild vision impairment, and 866 million (629 to 1150) will have uncorrected presbyopia. Interpretation: Age-adjusted prevalence of blindness has reduced over the past three decades, yet due to population growth, progress is not keeping pace with needs. We face enormous challenges in avoiding vision impairment as the global population grows and ages.Rupert R A Bourne ... Robert James Casson ... et al. (GBD 2019 Blindness and Vision Impairment Collaborators on behalf of the Vision Loss Expert Group of the Global Burden of Disease Study

Trends in prevalence of blindness and distance and near vision impairment over 30 years: an analysis for the Global Burden of Disease Study

Background To contribute to the WHO initiative, VISION 2020: The Right to Sight, an assessment of global vision impairment in 2020 and temporal change is needed. We aimed to extensively update estimates of global vision loss burden, presenting estimates for 2020, temporal change over three decades between 1990–2020, and forecasts for 2050. Methods We did a systematic review and meta-analysis of population-based surveys of eye disease from January, 1980, to October, 2018. Only studies with samples representative of the population and with clearly defined visual acuity testing protocols were included. We fitted hierarchical models to estimate 2020 prevalence (with 95% uncertainty intervals [UIs]) of mild vision impairment (presenting visual acuity ≥6/18 and <6/12), moderate and severe vision impairment (<6/18 to 3/60), and blindness (<3/60 or less than 10° visual field around central fixation); and vision impairment from uncorrected presbyopia (presenting near vision <N6 or <N8 at 40 cm where best-corrected distance visual acuity is ≥6/12). We forecast estimates of vision loss up to 2050. Findings In 2020, an estimated 43·3 million (95% UI 37·6–48·4) people were blind, of whom 23·9 million (55%; 20·8–26·8) were estimated to be female. We estimated 295 million (267–325) people to have moderate and severe vision impairment, of whom 163 million (55%; 147–179) were female; 258 million (233–285) to have mild vision impairment, of whom 142 million (55%; 128–157) were female; and 510 million (371–667) to have visual impairment from uncorrected presbyopia, of whom 280 million (55%; 205–365) were female. Globally, between 1990 and 2020, among adults aged 50 years or older, age-standardised prevalence of blindness decreased by 28·5% (–29·4 to −27·7) and prevalence of mild vision impairment decreased slightly (–0·3%, −0·8 to −0·2), whereas prevalence of moderate and severe vision impairment increased slightly (2·5%, 1·9 to 3·2; insufficient data were available to calculate this statistic for vision impairment from uncorrected presbyopia). In this period, the number of people who were blind increased by 50·6% (47·8 to 53·4) and the number with moderate and severe vision impairment increased by 91·7% (87·6 to 95·8). By 2050, we predict 61·0 million (52·9 to 69·3) people will be blind, 474 million (428 to 518) will have moderate and severe vision impairment, 360 million (322 to 400) will have mild vision impairment, and 866 million (629 to 1150) will have uncorrected presbyopia. Interpretation Age-adjusted prevalence of blindness has reduced over the past three decades, yet due to population growth, progress is not keeping pace with needs. We face enormous challenges in avoiding vision impairment as the global population grows and ages

Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020 : the right to sight : an analysis for the Global Burden of Disease Study

Background: Many causes of vision impairment can be prevented or treated. With an ageing global population, the demands for eye health services are increasing. We estimated the prevalence and relative contribution of avoidable causes of blindness and vision impairment globally from 1990 to 2020. We aimed to compare the results with the World Health Assembly Global Action Plan (WHA GAP) target of a 25% global reduction from 2010 to 2019 in avoidable vision impairment, defined as cataract and undercorrected refractive error.Methods: We did a systematic review and meta-analysis of population-based surveys of eye disease from January, 1980, to October, 2018. We fitted hierarchical models to estimate prevalence (with 95% uncertainty intervals [UIs]) of moderate and severe vision impairment (MSVI; presenting visual acuity from <6/18 to 3/60) and blindness (<3/60 or less than 10° visual field around central fixation) by cause, age, region, and year. Because of data sparsity at younger ages, our analysis focused on adults aged 50 years and older.Findings: Global crude prevalence of avoidable vision impairment and blindness in adults aged 50 years and older did not change between 2010 and 2019 (percentage change −0·2% [95% UI −1·5 to 1·0]; 2019 prevalence 9·58 cases per 1000 people [95% IU 8·51 to 10·8], 2010 prevalence 96·0 cases per 1000 people [86·0 to 107·0]). Age-standardised prevalence of avoidable blindness decreased by −15·4% [–16·8 to −14·3], while avoidable MSVI showed no change (0·5% [–0·8 to 1·6]). However, the number of cases increased for both avoidable blindness (10·8% [8·9 to 12·4]) and MSVI (31·5% [30·0 to 33·1]). The leading global causes of blindness in those aged 50 years and older in 2020 were cataract (15·2 million cases [9% IU 12·7–18·0]), followed by glaucoma (3·6 million cases [2·8–4·4]), undercorrected refractive error (2·3 million cases [1·8–2·8]), age-related macular degeneration (1·8 million cases [1·3–2·4]), and diabetic retinopathy (0·86 million cases [0·59–1·23]). Leading causes of MSVI were undercorrected refractive error (86·1 million cases [74·2–101·0]) and cataract (78·8 million cases [67·2–91·4]).Interpretation: Results suggest eye care services contributed to the observed reduction of age-standardised rates of avoidable blindness but not of MSVI, and that the target in an ageing global population was not reached

Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study

Background Many causes of vision impairment can be prevented or treated. With an ageing global population, the demands for eye health services are increasing. We estimated the prevalence and relative contribution of avoidable causes of blindness and vision impairment globally from 1990 to 2020. We aimed to compare the results with the World Health Assembly Global Action Plan (WHA GAP) target of a 25% global reduction from 2010 to 2019 in avoidable vision impairment, defined as cataract and undercorrected refractive error. Methods We did a systematic review and meta-analysis of population-based surveys of eye disease from January, 1980, to October, 2018. We fitted hierarchical models to estimate prevalence (with 95% uncertainty intervals [UIs]) of moderate and severe vision impairment (MSVI; presenting visual acuity from <6/18 to 3/60) and blindness (<3/60 or less than 10° visual field around central fixation) by cause, age, region, and year. Because of data sparsity at younger ages, our analysis focused on adults aged 50 years and older. Findings Global crude prevalence of avoidable vision impairment and blindness in adults aged 50 years and older did not change between 2010 and 2019 (percentage change −0·2% [95% UI −1·5 to 1·0]; 2019 prevalence 9·58 cases per 1000 people [95% IU 8·51 to 10·8], 2010 prevalence 96·0 cases per 1000 people [86·0 to 107·0]). Age-standardised prevalence of avoidable blindness decreased by −15·4% [–16·8 to −14·3], while avoidable MSVI showed no change (0·5% [–0·8 to 1·6]). However, the number of cases increased for both avoidable blindness (10·8% [8·9 to 12·4]) and MSVI (31·5% [30·0 to 33·1]). The leading global causes of blindness in those aged 50 years and older in 2020 were cataract (15·2 million cases [9% IU 12·7–18·0]), followed by glaucoma (3·6 million cases [2·8–4·4]), undercorrected refractive error (2·3 million cases [1·8–2·8]), age-related macular degeneration (1·8 million cases [1·3–2·4]), and diabetic retinopathy (0·86 million cases [0·59–1·23]). Leading causes of MSVI were undercorrected refractive error (86·1 million cases [74·2–101·0]) and cataract (78·8 million cases [67·2–91·4]). Interpretation Results suggest eye care services contributed to the observed reduction of age-standardised rates of avoidable blindness but not of MSVI, and that the target in an ageing global population was not reached

Prevalence and causes of vision loss in Latin America and the Caribbean in 2015: magnitude, temporal trends and projections

Objective To estimate the prevalence and causes of blindness and vision impairment for distance and near in Latin America and the Caribbean (LAC) in 2015 and to forecast trends to 2020. Methods A meta-analysis from a global systematic review of 283 cross-sectional, population-representative studies from published and unpublished sources from 1980 to 2014 in the Global Vision Database included 17 published and 6 unpublished studies from LAC. Results In 2015, across LAC, age-standardised prevalence was 0.38% in all ages and 1.56% in those over age 50 for blindness; 2.06% in all ages and 7.86% in those over age 50 for moderate and severe vision impairment (MSVI); 1.89% in all ages and 6.93% in those over age 50 for mild vision impairment and 39.59% in all ages and 45.27% in those over 50 for near vision impairment (NVI). In 2015, 117.86 million persons were vision impaired; of those 2.34 million blind, 12.46 million with MSVI, 11.34 million mildly impaired and 91.72 million had NVI. Cataract is the most common cause of blindness. Undercorrected refractive-error is the most common cause of vision impairment. Conclusions These prevalence estimates indicate that one in five persons across LAC had some degree of vision loss in 2015. We predict that from 2015 to 2020, the absolute numbers of persons with vision loss will increase by 12% to 132.33 million, while the all-age age-standardised prevalence will decrease for blindness by 15% and for other distance vision impairment by 8%. All countries need epidemiologic research to establish accurate national estimates and trends. Universal eye health services must be included in universal health coverage reforms to address disparities, fragmentation and segmentation of healthcar

Grand Challenges in global eye health: a global prioritisation process using Delphi method

Background We undertook a Grand Challenges in Global Eye Health prioritisation exercise to identify the key issues that must be addressed to improve eye health in the context of an ageing population, to eliminate persistent inequities in health-care access, and to mitigate widespread resource limitations. Methods Drawing on methods used in previous Grand Challenges studies, we used a multi-step recruitment strategy to assemble a diverse panel of individuals from a range of disciplines relevant to global eye health from all regions globally to participate in a three-round, online, Delphi-like, prioritisation process to nominate and rank challenges in global eye health. Through this process, we developed both global and regional priority lists. Findings Between Sept 1 and Dec 12, 2019, 470 individuals complete round 1 of the process, of whom 336 completed all three rounds (round 2 between Feb 26 and March 18, 2020, and round 3 between April 2 and April 25, 2020) 156 (46%) of 336 were women, 180 (54%) were men. The proportion of participants who worked in each region ranged from 104 (31%) in sub-Saharan Africa to 21 (6%) in central Europe, eastern Europe, and in central Asia. Of 85 unique challenges identified after round 1, 16 challenges were prioritised at the global level; six focused on detection and treatment of conditions (cataract, refractive error, glaucoma, diabetic retinopathy, services for children and screening for early detection), two focused on addressing shortages in human resource capacity, five on other health service and policy factors (including strengthening policies, integration, health information systems, and budget allocation), and three on improving access to care and promoting equity. Interpretation This list of Grand Challenges serves as a starting point for immediate action by funders to guide investment in research and innovation in eye health. It challenges researchers, clinicians, and policy makers to build collaborations to address specific challenge

Gas-phase formation and reactions of radical cations of guanosine, deoxyguanosine and their homodimers and heterodimers

Electrospray ionisation of methanolic solutions containing a mixture of the nucleoside deoxyguanosine, dG, incubated with Cu(NO3)2 resulted in the formation of a range of ions, including doubly charged copper nucleoside complexes [CuIIdGn]2+, with n ranging from 2 to 10. Collision-induced dissociation of these complexes proceeds via a number of different pathways that depend on the size of the cluster, n. When n = 3, monomeric radical cations are formed via redox processes. When n = 4, dimeric radical cations are formed. Related complexes are formed for the nucleoside guanosine, Gs, and these [CuIIGsn]2+ complexes fragment in similar fashions to their [CuIIdGn]2+ counterparts. A key finding is that the radical cations of dG and Gs have fragmentation patterns that depend on the way they are formed. Thus radical cations, dG•+ and Gs•+, formed directly in the electrospray ionisation source or via collision-induced dissociation of [CuIIdG3]2+ and [CuIIGs3]2+ complexes fragment in the same way, giving the radical cation of the guanine base at m/z 151 via cleavage of the N-glycosidic bond. In contrast, the collision-induced dissociation spectra of radical cations formed via the sequences [CuIIdG4]2+→ dG2 •+→ dG•+ and [CuIIGs4]2+→ Gs2 •+→ Gs•+ are dominated by the loss of CH2O and further loss of C2H3O2 from the sugar moiety. These different fragmentation reactions are attributed to different tautomeric structures of the radical cations. Quantum chemical calculations were carried out on possible structures of the radical cation dimer of the model 9-methylguanine. Three low energy structures were found. Two of these represent base pairs of the kind found in supramolecular motifs of guanine derivatives, and one of these possesses a novel tautomeric structure that may have important biological implications

Gas phase synthesis and reactivity of dimethylaurate

A combination of multistage <annref idrefs="ann1">mass spectrometry</annref> experiments and DFT calculations were used to examine the synthesis and reactivity of <compname idrefs="chem1">dimethylaurate</compname>. <annref idrefs="ann2">Collision induced dissociation</annref> (<annref idrefs="ann2">CID</annref>) of [(CH<small>₃</small>CO<small>₂</small>)<small>₄</small>Au]<small>⁻</small> proceeded <em>via</em> reductive elimination of <compname idrefs="chem3">acetylperoxide</compname> to yield the <annref idrefs="ann3">diacetate</annref> [CH<small>₃</small>CO<small>₂</small>AuO<small>₂</small>CCH<small>₃</small>]<small>⁻</small>, which in turn underwent sequential <annref idrefs="ann2">CID</annref> decarboxylation reactions to yield the organoaurates [CH<small>₃</small>CO<small>₂</small>AuCH<small>₃</small>]<small>⁻</small> and [CH<small>₃</small>AuCH<small>₃</small>]<small>⁻</small>. The unimolecular chemistry of the <annref idrefs="ann3">dimethylaurate</annref> proceeds <em>via</em> a combination of bond homolysis to yield the <annref idrefs="ann4">methyl</annref> aurate <annref idrefs="ann5">radical anion</annref> [CH<small>₃</small>Au]˙<small>⁻</small> as well as formation of the <compname idrefs="chem4">gold dihydride</compname> [<compname idrefs="chem5">HAuH</compname>]<small>⁻</small>. DFT calculations reveal that the latter anion is formed <em>via</em> a 1,2-dyotropic <annref idrefs="ann6">rearrangement</annref> to yield the isomer [CH<small>₃</small>CH<small>₂</small>AuH]<small>⁻</small>, followed by a <annref idrefs="ann3">β-hydride</annref> <annref idrefs="ann7">elimination reaction</annref>. Ion-molecule reactions of [CH<small>₃</small>AuCH<small>₃</small>]<small>⁻</small> with <compname idrefs="chem6">methyl iodide</compname> did not yield any products even at relatively high concentrations of the neutral substrate and longer reaction times, indicating a reaction efficiency of less than 1 in 20 000 collisions. DFT calculations were carried out on two different potential energy surfaces (<annref idrefs="ann8">PES</annref>) for the reaction of [CH<small>₃</small>AuCH<small>₃</small>]<small>⁻</small> with CH<small>₃</small>I: (i) an S<small>_N</small>2 mechanism proceeding <em>via</em> a side-on transition state; and (ii) a stepwise mechanism proceeding <em>via</em> oxidative addition followed by reductive elimination. Both pathways have significant endothermic barriers, consistent with the lack of C–C bond coupling products being formed in the experiments. Finally, the reactivity of [CH<small>₃</small>AuCH<small>₃</small>]<small>⁻</small> is compared to the previously studied [CH<small>₃</small>AgCH<small>₃</small>]<small>⁻</small> and [CH<small>₃</small>CuCH<small>₃</small>]<small>⁻</small>, as well as condensed phase studies on <compname idrefs="chem1">dimethylaurate</compname> salts

Mass Spectrometric and Computational Studies on the Reaction of Aromatic Peroxyl Radicals with Phenylacetylene Using the Distonic Radical Ion Approach

Product and mechanistic studies were performed for the reaction of aromatic distonic peroxyl radical cations 4-PyrOO^•+ and 3-PyrOO^•+ with phenylacetylene (<b>7</b>) in the gas phase using mass spectrometric and computational techniques. PyrOO^•+ was generated through reaction of the respective distonic aryl radical cation Pyr^•+ with O₂ in the ion source of the mass spectrometer. For the reaction involving the more electrophilic 4-PyrOO^•+, a rate coefficient of <i>k</i>₁ = (2.2 ± 0.6) × 10^–10 cm³ molecule^–1 s^–1 was determined at 298 K, while a value of <i>k</i>₂ = (8.2 ± 2.1) × 10^–11 cm³ molecule^–1 s^–1 was obtained for the reaction involving the less electrophilic 3-PyrOO^•+. This highlights the role of polar effects in these reactions, which are likely of high relevance for processes in combustions and atmospheric transformations. The mechanism was studied by computational methods, which showed that radical addition occurs exclusively at the less substituted alkyne site to give the distonic vinyl radical cation <b>8</b>. The latter undergoes a series of subsequent rearrangements/fragmentations that are similar for both isomeric PyrOO^•+. γ-Fragmentation in <b>8</b> leads to the distonic aryloxyl radical cation PyrO^•+ and a singlet carbene <b>10</b>. The product association complex [PyrO^•+ – <b>10</b>] is the starting point for two important subsequent reactions, e.g., (i) rapid hydrogen transfer to form ketenyl radical <b>11</b> and the closed-shell species PyrOH⁺, and (ii) oxygen transfer from PyrO^•+ to <b>10</b> that leads to α-keto aldehyde <b>13</b> and Pyr^•+, followed by hydrogen abstraction to give acyl radical <b>14</b> and PyrH⁺. Additional major products are the closed-shell aromatic carbonyl compounds <b>20</b> and <b>30</b> that result from multistep rearrangements in vinyl radical <b>8</b>, which are terminated by homolytic bond scission and release of neutral acyl radicals