Global estimates on the number of people blind or visually impaired by age-related macular degeneration: A meta-analysis from 2000 to 2020

doi:10.21203/rs.3.rs-3139773/v1

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Global estimates on the number of people blind or visually impaired by age-related macular degeneration: A meta-analysis from 2000 to 2020

https://doi.org/10.21203/rs.3.rs-3139773/v1

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published 04 Jul, 2024

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Background:We aimed to update estimates of global vision loss due to age-related macular degeneration (AMD).

Methods:We did a systematic review and meta-analysis of population-based surveys of eye diseases from January, 1980, to October, 2018. We fitted hierarchical models to estimate prevalence of moderate and severe vision impairment (MSVI; presenting visual acuity from <6/18 to 3/60) and blindness (<3/60) caused by AMD, stratified by age, region, and year.

Results:In 2020, 1.85 million (95%UI: 1.35-2.43 million) people were blind due to AMD, and another 6.23 million (95%UI: 5.04-7.58) million presented with MSVI globally. High-income countries hadthe highest number of individuals with AMD-related blindness (0.60 million people; 0.46-0.77). The crude prevalence of blindness due to AMD in 2020 (among those aged ≥ 50years) was 0.10% (0.07-0.12) globally, and the region with the highest prevalence of blindness due to AMD was North Africa/Middle East (0.22%; 0.16-0.30). Age-standardized prevalence of MSVI due to AMD in people aged ≥ 50 years in 2020 was 0.34% (0.27-0.41) globally, and the region with the highest prevalence of MSVI due to AMD was also North Africa/Middle East (0.55%; 0.44-0.68). From 2000 to 2020, the crude prevalence of blindness due to AMD decreased globally by 19.29% (19.57 to 19.01%), while the prevalence of MSVI increased by 10.08%(9.81 to 10.34%).

Conclusions:The increase in the number of individuals with AMD-related blindness and MSVI globally due to population growth and ageing urge for creation of novel treatment modalities and the expansion of rehabilitation services.

Health sciences/Medical research/Epidemiology

Health sciences/Diseases/Eye diseases/Retinal diseases

Age-related macular degeneration (AMD) is an acquired, degenerative disorder affecting the macula of older adults¹. The disease, characterised by a panoply of features in the macular region, such as drusen of the retinal pigment epithelium (RPE), RPE cell depigmentation and proliferation, detachment of the RPE layer from Bruch´s membrane, loss of RPE cells and subretinal choroidal neovascularization¹, is categorized into a non-exudative (or “dry”) stage and an exudative (or ‘wet’) stage. Older age, genetic background and family history, European ancestry, and smoking belong to the risk factors for the development and progression of the disease¹.

Significant progress has been made in the treatment of the exudative stage of AMD over the last two decades due to the clinical introduction of intraocular injections of anti-vascular endothelial growth factor (VEGF) drugs², but AMD has remained a challenge in global eye health care due to its relatively high prevalence and since the non-exudative stage as the most common form of AMD cannot effectively be treated yet. AMD has thus high importance as cause of vision impairment and blindness³, with the sequels such as a reduction of the quality of life⁴ and economic impact due to loss of productivity⁵.

Although AMD-related blindness is a growing global problem due to population ageing, its importance is not homogeneous across world regions. In countries with a higher cataract surgical coverage (usually high-income countries), chronic eye conditions such as AMD account for a relatively more significant proportion of blindness⁶.

To contribute to the World Health Organization (WHO) World Report on Vision⁷ and the implementation of the recommendations generated⁸, The Vision Loss Expert Group (VLEG) of the Global Burden of Disease (GBD) Study calculated estimates of the leading causes of vision impairment and blindness, like AMD^9,10,11,3. Such estimates are essential for monitoring, action planning, and advocacy⁶. In this meta-analysis, we aimed to update estimates of global vision loss burden due to age-related macular degeneration (AMD), presenting estimates for 2020, temporal changes, and distribution by sex and world region.

The data was arranged following an orderly review of published population-focused studies on vision impairment and blindness by the VLEG. This review included studies published between Jan 1, 1980, and Oct 1, 2018, incorporating grey literature as well. Relevant studies from this review were combined with data from Rapid Assessment of Avoidable Blindness (RAAB) studies by VLEG. Data was also sourced from the US National Health and Nutrition Examination survey and the WHO Study on Global Ageing and Adult Health, contributed by the GBD team. More detailed methods are published elsewhere^10,3 and discussed in brief as follows.

In total, VLEG pinpointed 137 studies and pulled data from 70 studies in their 2010 review, and 67 additional studies in their 2014–18 review. Most of these studies were national or subnational cross-sectional surveys. VLEG also arranged for the production of 5-year age-segregated RAAB data from the RAAB repository. To qualify, studies had to meet specific criteria: vision acuity data must be gathered through a test chart compatible with the Snellen scale, and the sample had to be representative of the population. Subjective reports of vision loss were not included. The criteria for vision loss was defined by the International Classification of Diseases 11th edition as employed by WHO. It was based on the vision in the better eye upon presentation. Moderate vision loss was defined as a visual acuity of 6/60 or better but less than 6/18, severe vision loss as a visual acuity of 3/60 or better but less than 6/60, and blindness as a visual acuity of less than 3/60 or less than 10° visual field around central fixation (although the visual field definition was rarely used in population-based eye surveys).

We split the original data into several datasets, creating separate envelopes for each degree of vision loss (mild, moderate, and severe) and blindness. This data was then fed into a meta-regression tool designed by the Institute for Health Metrics and Evaluation (IHME) known as MR-BRT (meta regression; Bayesian; regularised; trimmed). The benchmark for each severity level was presenting vision impairment.

Data about uncorrected refractive errors were pulled straight from the data sources when possible, and if not, they were calculated by subtracting the best-corrected vision impairment from presenting vision impairment prevalence at each level of severity. Other causes were factored into the best-corrected estimates for each level of vision impairment.

Our models for distance vision impairment and blindness were based on the most commonly reported causes found in the literature, and the minimum age for inclusion of data on AMD was 45 years. We created estimates of MSVI and blindness that were specific to location, year, age, and sex using Disease Modelling Meta-Regression (Dismod-MR) 2.1¹². Its data processing steps have been outlined elsewhere³. Briefly, Dismod-MR 2.1 models were run for all vision impairment by severity (moderate, severe, blindness) regardless of cause and, separately, for MSVI and blindness due to each modelled cause of vision impairment. Then, models of MSVI due to specific causes were split into moderate and severe estimates using the ratio of overall prevalence in the all-cause moderate presenting vision impairment and severe presenting vision impairment models. Next, prevalence estimates for all causes by severity were scaled to the models of all-cause prevalence by severity. This produced final estimates by age, sex, year, and location for each individual cause of vision impairment by severity. We age-standardised our estimates using the GBD standard population¹³. Data on blindness and MSVI due to AMD were presented by seven super-regions (Southeast Asia/East Asia/Oceania, Central Europe/Eastern Europe/Central Asia, High-income, Latin America and Caribbean, North Africa and Middle East, South Asia, and Sub-Saharan Africa and globally. Data on other causes of vision impairment and blindness will be presented in separate publications.

In 2020, 1.85 million (all ages; 95% uncertainty interval (UI): 1.35–2.43 million) people were blind due to AMD, with 664,000 (472,000-894,000) males and 1,185,000 (876,000–1,545,000) females affected (Table 1, 2). AMD-related MSVI affected 6.23 million (95%UI: 5.04–7.58) individuals worldwide, among them 2,747,000 (2,207,000–3,377,000) males and 2,743,000 (2,202,000–3,371,000) females (Table 1,3).

Table 1

Number of people (mean [95% UI]) with blindness (presenting visual acuity < 3/60) or MSVI (presenting visual acuity < 6/18, ≥ 3/60) due to AMD, the age-standardized prevalence (%) in people of all ages and aged ≥ 50 years (mean [95% UI]), and the percentage of all blindness or MSVI attributed to AMD (95% UI) in world regions in 2020
		Blindness due to AMD in 2020			MSVI due to AMD in 2020
World Region	2020, total population (‘000s)	Number of people (‘000s) with blindness in 2020 (all ages)	Age-standardized prevalence of AMD blindness in 2020 (aged ≥ 50 years)	Percentage of all AMD blindness in 2020 ≥ (50 years)	Number of people (‘000s) with MSVI in 2020 (all ages)	Age-standardized prevalence of AMD MSVI in people ≥ 50 years aged in 2020	Percentage of AMD MSVI in 2020 (≥ 50 years)
Global	7,890,000	1,850 (1,349-2,434)	0.10 (0.08–0.14)	4.30 (3.14–5.66)	6,231(5,042 − 7,587)	0.34 (0.27–0.41)	2.11 (1.71–2.57)
Southeast Asia, East Asia, and Oceania	2,192,710	495 (342–680)	0.08 (0.06–0.11)	3.29 (2.27–4.51)	2,762 (2,211-3,379)	0.46 (0.37–0.56)	3.33 (2.66–4.07)
Central Europe, Eastern Europe, and Central Asia	417,291	62 (43–84)	0.04 (0.03–0.06)	4.43 (3.07–5.95)	228 (182–282)	0.16 (0.13–0.19)	1.27 (1.01–1.57)
High-income	1,087,856	596 (456–769)	0.11 (0.08–0.14)	19.82 (15.17–25.60)	739 (584–917)	0.14 (0.11–0.17)	2.38 (1.88–2.95)
Latin America and Caribbean	601,551	71(49–97)	0.05 (0.04–0.07)	1.95 (1.35–2.66)	333 (270–407)	0.25 (0.21–0.31)	1.36 (1.10–1.67)
North Africa and Middle East	631,727	195(136–264)	0.22 (0.16–0.30)	6.31 (4.43–8.55)	493 (391–614)	0.55 (0.44–0.68)	2.26 (1.79–2.81)
South Asia	1,841,435	297 (200–423)	0.10 (0.07–0.15)	2.49 (1.68–3.55)	1,220 (972-1,510)	0.42 (0.34–0.51)	1.27 (1.01–1.57)
Sub-Saharan Africa	1,114,806	131 (92–178)	0.15 (0.11–0.20)	2.58 (1.81–3.51)	454 (360–565)	0.50 (0.40–0.61)	2.22 (1.76–2.77)

Table 2

Number of males and females with blindness (presenting visual acuity < 3/60), and the age-standardized prevalence (% [95% UI]) of blindness due to AMD (all ages and people aged ≥ 50 years) in 2020.
	Total Population	Total number of AMD blindness and aged-standardized AMD blindness in 2020 (all ages)				Total Number of AMD blindness and aged-standardized AMD blindness in people aged 50 + years in 2020
World Region	2020, total population (‘000s)	Number of males(‘000s) with AMD blindness in 2020	Number of females (‘000s) with AMD blindness in 2020	Age standardized prevalence of blindness in males in 2020	Age standardized prevalence of blindness in females in 2020	Number of males(‘000s) (50 + years) with AMD blindness in 2020	Number of females(‘000s) (50 + years) with AMD blindness in 2020	Age standardized prevalence of blindness in males in 2020	Age standardized prevalence of blindness in females in 2020
Global	7,890,000	664 (472–894)	1,185 (876-1,545)	0.02 (0.01–0.02)	0.03 (0.02–0.03)	660 (469–890)	1,180 (871-1,540)	0.08 (0.06–0.11)	0.12 (0.09–0.16)
Southeast Asia, East Asia, and Oceania	2,192,710	185 (128–257)	309 (214–424)	0.01 (0.01–0.02)	0.02 (0.01–0.03)	184 (126–254)	307 (212–422)	0.07 (0.05–0.09)	0.10 (0.07–0.13)
Central Europe, Eastern Europe, and Central Asia	417,291	20 (14–28)	42(29–56)	0.01 (0.01–0.01)	0.01 (0.01–0.01)	20 (14–27)	41 (29–56)	0.04 (0.03–0.05)	0.05 (0.03–0.06)
High-income	1,087,856	168 (124–222)	427 (327–543)	0.02 (0.01–0.02)	0.03 (0.02–0.04)	168(124–221)	427 (327–542)	0.08 (0.06–0.10)	0.13 (0.10–0.17)
Latin America and Caribbean	601,551	23 (15–32)	48 (33–65)	0.01 (0.01–0.01)	0.01 (0.01–0.02)	23(15–32)	47 (33–65)	0.04 (0.03–0.06)	0.07 (0.05–0.09)
North Africa and Middle East	631,727	77 (53–105)	117 (81–159)	0.04 (0.03–0.05)	0.06 (0.04–0.08)	77(53–104)	116 (81–158)	0.18 (0.13–0.25)	0.26 (0.18–0.35)
South Asia	1,841,435	142 (95–199)	155(105–221)	0.02 (0.02–0.03)	0.02 (0.02–0.03)	141(94–198)	154 (104–219)	0.10 (0.07–0.15)	0.11 (0.07–0.15)
Sub-Saharan Africa	1,114,806	46 (32–62)	85 (59–115)	0.03 (0.02–0.03)	0.04 (0.03–0.05)	45 (32–62)	84 (59–114)	0.11 (0.08–0.16)	0.18 (0.13–0.24)

Table 3

Number of males and females with AMD MSVI, and the age-standardized prevalence (% [95% uncertainty intervals (UIs)]) of AMD MSVI (all ages and people aged ≥ 50 years) in 2020.
	Total Population	Total number of AMD MSVI and aged-standardized AMD MSVI in 2020 (all ages)				Total number of AMD MSVI and aged-standardized AMD MSVI in people aged 50 + years in 2020
World Region	2020, total population (‘000s)	Number of males(‘000s) with AMD MSVI in 2020	Number of females (‘000s) with AMD MSVI in 2020	Age standardized prevalence of MSVI in males in 2020	Age standardized prevalence of MSVI in females in 2020	Number of females(‘000s) (50 + years) with AMD MSVI in 2020	Number of females(‘000s) (50 + years) with AMD MSVI in 2020	Age standardized prevalence of MSVI in males in 2020	Age standardized prevalence of MSVI in females in 2020
Global	7,890,000	2,747 (2,207-3,377)	3,483 (2,823-4,236)	0.07 (0.06–0.09)	0.08 (0.06–0.09)	2,743 (2,202-3,371)	3,478 (2,816-4,226)	0.33 (0.27–0.40)	0.35 (0.28–0.43)
Southeast Asia, East Asia, and Oceania	2,192,710	1,231 (982–1501)	1,530 (1,224-1,865)	0.10 (0.08–0.12)	0.11 (0.08–0.13)	1,230 (981-1,500)	1,528 (1,223-1,862)	0.44 (0.36–0.54)	0.48 (0.39–0.59)
Central Europe, Eastern Europe, and Central Asia	417,291	75 (60–94)	152 (121–188)	0.03 (0.02–0.04)	0.04 (0.03–0.05)	75 (60–94)	152 (121–188)	0.14 (0.11–0.18)	0.17 (0.13–0.21)
High-income	1,087,856	294 (232–363)	445 (350–554)	0.03 (0.02–0.04)	0.03 (0.03–0.04)	293 (232–362)	444 (350–553)	0.13 (0.10–0.16)	0.15 (0.12–0.18)
Latin America and Caribbean	601,551	137 (110–168)	196 (159–240)	0.05 (0.04–0.06)	0.06 (0.05–0.07)	136 (109–168)	195 (158–239)	0.23 (0.19–0.29)	0.27 (0.22–0.33)
North Africa and Middle East	631,727	234 (185–295)	258 (204–320)	0.12 (0.09–0.14)	0.12 (0.10–0.15)	234 (185–295)	258 (204–320)	0.53 (0.42–0.65)	0.57 (0.45–0.70)
South Asia	1,841,435	571 (453–704)	649 (518–802)	0.09 (0.07–0.11)	0.09 (0.08–0.12)	570 (452–703)	647 (517–800)	0.41 (0.33–0.49)	0.43 (0.35–0.53)
Sub-Saharan Africa	1,114,806	202(160–253)	251 (198–313)	0.11 (0.09–0.13)	0.11 (0.09–0.14)	202 (160–252)	250 (198–313)	0.49 (0.39–0.60)	0.50 (0.40–0.63)

High-income countries (0.60 million people; 0.46–0.77) accounted for the highest number of individuals with AMD-related blindness per world region, whereas the lowest number of individuals with presenting blindness due to AMD per world region was found in Central Europe / Eastern Europe / Central Asia combined (0.06 million people; 0.04–0.08) and Latin America and the Caribbean (0.07 million people; 0.50 − 0.1) (Table 1).

The crude prevalence of AMD-related blindness in those aged ≥ 50 years in 2020 was 0.10% (0.07–0.12) globally, and the regions with the highest prevalence of blindness due to AMD were North Africa/Middle East 0.22% (0.16–0.30) and Sub-Saharan Africa 0.15% (0.11–0.20). Age-standardized prevalence of MSVI due to AMD in those aged ≥ 50 years in 2020 was 0.34% (0.27–0.41) globally, and the regions with the highest prevalence of MSVI due to AMD were also North Africa/Middle East (0.55%; 0.44–0.68) and Sub-Saharan Africa (0.50%; 0.40–0.61) (Table 1).

From 2000 to 2020, the crude prevalence of blindness due to AMD decreased globally by 19.29% (19.57 to 19.01%), with a wide variety between regions, from − 32.58% (-32.85 to -32.31%) in Southeast Asia, East Asia, and Oceania to + 1.28% (0.88 to 1.68%) in Latin America and Caribbean, the only region which showed an increase (Table 4). On the other hand, over the same period the crude prevalence of MSVI due to AMD increased globally by 10.08% (9.81 to 10.34%), with changes varying from − 9.28% (-9.52 to -9.04%) in North Africa and Middle East to + 7.19 (6.93 to 7.46%) in Southeast Asia, East Asia, and Oceania (Table 5).

Table 4

Percentage change in crude prevalence of AMD blindness (presenting visual acuity < 3/60) in adults age 50 years and older between 2000 and 2020 by world super region.
	Crude Prevalence			Number of Cases ('000s)			Age standardized prevalence
World Region	Male (%, 95% UI)	Female (%, 95% UI)	Both (%, 95% UI)	Male (%, 95% UI)	Female (%, 95% UI)	Both (%, 95% UI)	Male (%, 95% UI)	Female (%, 95% UI)	Both (%, 95% UI)
Global	-18.77 (-19.08to-18.46)	-19.52 (-19.78to-19.25)	-19.29 (-19.57to-19.01)	43.26 (42.72to43.80)	41.38 (40.92to41.85)	42.05 (41.57to42.54)	-22.17 (-22.45to-21.90)	-21.74 (-22.00to-21.49)	-22.58 (-22.84to-22.32)
High-income	3.85 (3.51to4.20)	-4.19 (-4.47to-3.92)	-3.12 (-3.41to-2.83)	52.83 (52.32to53.34)	33.45 (33.07to33.84)	38.41 (37.99to38.82)	-12.77 (-13.06to-12.49)	-14.42 (-14.66to-14.17)	-15.75 (-16.00to-15.50)
Central Europe, Eastern Europe, and Central Asia	1.92 (1.51to2.33)	-10.02 (-10.37to-9.67)	-6.94 (-7.30to-6.58)	32.21 (31.68to32.74)	11.32 (10.89to11.76)	17.42 (16.96to17.87)	-4.98 (-5.34to-4.62)	-15.05 (-15.38to-14.73)	-12.65 (-12.99to-12.32)
Latin America and Caribbean	-2.59 (-3.00to-2.18)	2.53 (2.12to2.94)	1.28 (0.88to1.68)	91.96 (91.15to92.77)	109.87 (109.03to110.70)	103.64 (102.83to104.45)	-6.64 (-7.02to-6.25)	-3.69 (-4.08to-3.31)	-4.09 (-4.47to-3.71)
North Africa and Middle East	-23.76 (-24.06to-23.46)	-18.36 (-18.69to-18.04)	-20.59 (-20.91to-20.28)	58.40 (57.77to59.02)	69.88 (69.21to70.56)	65.11 (64.45to65.76)	-17.40 (-17.72to-17.08)	-16.41 (-16.74to-16.09)	-16.36 (-16.68to-16.04)
South Asia	-28.34 (-28.65to-28.03)	-32.65 (-32.94to-32.36)	-30.49 (-30.80to-30.19)	35.24 (34.66to35.82)	36.16 (35.58to36.75)	35.72 (35.13to36.31)	-28.49 (-28.79to-28.19)	-34.14 (-34.42to-33.87)	-31.40 (-31.68to-31.11)
Southeast Asia, East Asia, and Oceania	-33.81 (-34.07to-33.54)	-32.18 (-32.45to-31.91)	-32.58 (-32.85to-32.31)	30.89 (30.35to31.42)	38.34 (37.79to38.89)	35.45 (34.91to35.99)	-36.28 (-36.53to-36.03)	-32.52 (-32.78to-32.26)	-34.07 (-34.32to-33.81)
Sub-Saharan Africa	-11.92 (-12.26to-11.58)	-12.37 (-12.71to-12.04)	-11.22 (-11.56to-10.87)	55.82 (55.21to56.43)	69.99 (69.34to70.64)	64.73 (64.09to65.37)	-7.40 (-7.75to-7.04)	-6.82 (-7.17to-6.46)	-6.60 (-6.96to-6.25)

Table 5

Percentage change in crude prevalence of AMD MSVI (presenting visual acuity < 6/18, ≥ 3/60) and in adults aged 50 years and older between 2000 and 2020 by world super region
	Crude Prevalence			Number of Cases ('000s)			Age standardized prevalence
World Region	Male (%, 95% UI)	Female (%, 95% UI)	Both (%, 95% UI)	Male (%, 95% UI)	Female (%, 95% UI)	Both (%, 95% UI)	Male (%, 95% UI)	Female (%, 95% UI)	Both (%, 95% UI)
Global	9.84 (9.57to10.12)	10.29 (10.03to10.55)	10.08 (9.81to10.34)	93.72 (93.24to94.21)	93.75 (93.29to94.21)	93.74 (93.27to94.20)	6.54 (6.29to6.79)	10.50 (10.24to10.76)	8.65 (8.39to8.90)
High-income	12.88 (12.58to13.17)	2.08 (1.81to2.36)	5.58 (5.30to5.85)	66.11 (65.68to66.55)	42.19 (41.81to42.58)	50.83 (50.43to51.23)	-3.15 (-3.40to-2.90)	-4.98 (-5.23to-4.74)	-4.79 (-5.04to-4.55)
Central Europe, Eastern Europe, and Central Asia	6.94 (6.64to7.23)	7.11 (6.82to7.39)	6.61 (6.33to6.89)	38.71 (38.33to39.08)	32.51 (32.16to32.86)	34.51 (34.15to34.86)	-0.03 (-0.29to0.23)	4.29 (4.02to4.56)	2.63 (2.36to2.90)
Latin America and Caribbean	3.68 (3.42to3.94)	7.84 (7.58to8.10)	6.26 (6.01to6.52)	104.32 (103.80to104.83)	120.73 (120.20to121.26)	113.66 (113.15to114.18)	0.03 (-0.22to0.28)	3.91 (3.66to4.16)	2.38 (2.14to2.63)
North Africa and Middle East	-11.93 (-12.17to-11.69)	-6.73 (-6.98to-6.48)	-9.28 (-9.52to-9.04)	82.97 (82.48to83.47)	94.09 (93.57to94.61)	88.64 (88.14to89.14)	-4.57 (-4.81to-4.32)	-3.18 (-3.43to-2.93)	-3.82 (-4.07to-3.57)
South Asia	5.75 (5.47to6.03)	2.08 (1.81to2.34)	4.03 (3.75to4.30)	99.57 (99.05to100.09)	106.37 (105.83to106.90)	103.13 (102.60to103.66)	0.38 (0.14to0.63)	-3.23 (-3.46to-3.00)	-1.45 (-1.69to-1.21)
Southeast Asia, East Asia, and Oceania	7.44 (7.17to7.71)	6.75 (6.49to7.01)	7.19 (6.93to7.46)	112.45 (111.91to112.98)	117.75 (117.22to118.28)	115.35 (114.81to115.89)	5.66 (5.41to5.92)	7.25 (6.99to7.51)	6.42 (6.17to6.67)
Sub-Saharan Africa	-8.44 (-8.69to-8.20)	-0.49 (-0.75to-0.23)	-4.16 (-4.41to-3.91)	61.97 (61.54to62.40)	93.05 (92.54to93.55)	77.81 (77.35to78.28)	-2.49 (-2.73to-2.25)	4.08 (3.82to4.35)	0.70 (0.45to0.95)

In 2020, AMD ranked second among the causes of irreversible blindness globally³. From 2000 to 2020, there was a decrease in the prevalence of AMD-related blindness in all regions except Latin America and the Caribbean, and an increase in the prevalence of AMD-related MSVI in all regions except North Africa and Middle East, and Sub-Saharan Africa, with wide discrepancies between regions. The global population growth and increasing life expectancy can explain the increasing number of individuals with AMD-related vision loss.

Prevalence of blindness and MSVI due to AMD is higher in older age groups, and countries with a growing life expectancy should take this information into account for a better health service planning. But considering the current barriers to access AMD treatment and rehabilitation services in many regions, even a minor increase in absolute numbers might put pressure on the already overloaded public health systems. The reduced availability of ophthalmic services during the Covid-19 pandemic¹⁴ and the economic impact that might be seen during the post-pandemic years can increase barriers in the management of chronic eye conditions, like AMD.

Dealing with AMD from a public health perspective is a complex task. First, although diagnosis is easily performed by a trained ophthalmologist, the availability and distribution of eye care professionals remain an issue in many parts of the world¹⁵. The growing use of telemedicine and artificial intelligence in ophthalmology, if well connected to public health initiatives, will likely reduce the percentage of those with undiagnosed AMD. Second, its first-line treatment, intravitreal anti-VEGF injection, can be expensive, its effect lasts only a few months, and is only indicated for the wet form of the disease. And finally, those with MSVI and blindness due to AMD would benefit from rehabilitation services, and its availability is also scarce¹⁶. The integration between education for those at a higher risk for developing AMD diagnosis, treatment, and rehabilitation, using a people-centred approach⁷, could reduce the burden of AMD.

Strengths of the present study included the number of population-based data accessed and used, analysis of trends in the causes of blindness and MSVI, incorporation of nonlinear age trends and accounting for data that were not reported by age, and systematic quantitative analysis and reporting of uncertainty. Among the limitations of the present study, we can cite the shortage of data in some countries/regions and information on the burden of AMD in ethnic minorities, such as indigenous people. In some countries, population-based data were either collected sub nationally or more than a decade ago, and estimates may not represent the current reality of a given country. Also, most analysed studies used either the Rapid Assessment of Cataract Surgical Services or Rapid Assessment of Avoidable Blindness methodologies, which may underestimate posterior pole diseases, such as AMD¹⁷.

Policymakers and the academic community should have in mind that the social and economic impact of AMD is expected to increase substantially due to population growth and ageing⁶. Different from cataract and uncorrected refractive errors, the leading causes of blindness and vision impairment, respectively, the burden of AMD can only be alleviated if significant advances in research are made. The development of novel, cost-effective treatment modalities is paramount for the management of AMD for the next decades.

Funding: This study was funded by Brien Holden Vision Institute, Fondation Thea, Fred Hollows Foundation, Bill & Melinda Gates Foundation, Lions Clubs International Foundation (LCIF), Sightsavers International, and University of Heidelberg.

Conflict of interest: Will be provided later in the submission process for all authors.

This paper has not been published elsewhere previously and it is not simultaneously being considered for any other publication.

Author contributions: RRAB, IT, AF, MVC, AA, NL conducted the search. PSB, TV, and JS performed the statistical analysis. JF and JBJ drafted the manuscript. All authors reviewed, edited and finalised the manuscript.

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Global estimates on the number of people blind or visually impaired by age-related macular degeneration: A meta-analysis from 2000 to 2020

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