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Table 3 Estimation of blindness and visual impairment including that caused by uncorrected refractive error in different GBD sub-regions.

From: What is the global burden of visual impairment?

GBD sub-region Population (millions) Number blind with ICD definition* (millions) Number having low vision with ICD definition* (millions) Total number having visual impairment with ICD definition* (millions) Proportion of blindness estimated due to uncorrected refractive error Proportion of less severe visual impairment estimated due to uncorrected refractive error Number blind including un-corrected refractive error† (millions) Number having less severe visual impairment including uncorrected refractive error† (millions) Total number having visual impairment including uncorrected refractive error† (millions) Increase in number with visual impairment due to uncorrected refractive error (millions)
AFRO D‡ 354 3.65 10.72 14.36 0.08 0.29 3.96 15.09 19.05 4.69
AFRO E 361 3.64 10.57 14.22 0.08 0.29 3.96 14.89 18.85 4.64
AMR A§ 322 0.69 4.03 4.72 0 0.38 0.69 6.50 7.19 2.47
AMR B¶ 456 1.39 7.60 8.99 0.10 0.45 1.55 13.82 15.36 6.37
AMR D# 74 0.33 1.49 1.82 0.15 0.45 0.39 2.71 3.10 1.28
EMRO B** 143 1.08 3.58 4.66 0.13 0.45 1.24 6.51 7.75 3.09
EMRO D# 144 1.41 4.12 5.52 0.15 0.45 1.65 7.48 9.14 3.62
EURO A§ 415 0.94 5.44 6.37 0 0.38 0.94 8.77 9.70 3.33
EURO B1 170 0.62 2.55 3.16 0.12 0.29 0.70 3.59 4.29 1.12
EURO B2†† 53 0.14 0.59 0.73 0.12 0.29 0.16 0.83 0.99 0.26
EURO C†† 240 1.04 4.22 5.25 0.12 0.29 1.18 5.94 7.12 1.86
SEARO B‡‡ 405 4.21 9.67 13.88 0.10 0.45 4.68 17.58 22.26 8.38
SEARO D§§ 1394 8.34 28.44 36.78 0.15 0.45 9.82 51.71 61.52 24.74
WPRO A§ 151 0.39 1.88 2.28 0 0.38 0.39 3.04 3.43 1.15
WPRO B1¶¶ 1375 7.73 26.40 34.13 0.16 0.50 9.20 52.79 62.00 27.87
WPRO B2¶¶ 148 1.23 2.90 4.13 0.16 0.50 1.46 5.80 7.26 3.13
WPRO B3¶¶ 8 0.03 0.09 0.12 0.12 0.40 0.03 0.15 0.18 0.06
Total 6213 36.86 124.27 161.12 0.12 0.43 42.01 217.19 259.19 98.07
  1. Some totals may not match exactly due to rounding off.
  2. *These numbers with blindness (best-corrected visual acuity less than 3/60), low vision (best-corrected visual acuity less than 6/18 to 3/60) and visual impairment (best-corrected visual acuity less than 6/18) are from the WHO estimate using the ICD classification [1].
  3. †Number of blind including uncorrected refractive error = Number of blind with ICD definition/(1 - Proportion of blindness estimated due to uncorrected refractive error); Number having less severe visual impairment including uncorrected refractive error = Number having low vision with ICD definition/(1 - Proportion of less severe visual impairment estimated due to uncorrected refractive error); total number having visual impairment including uncorrected refractive error is sum of the previous two.
  4. ‡Data from a national survey in Gambia in AFRO D sub-region could not be used as refractive error as a cause of visual impairment was mixed with "other" causes [21]; although data regarding contribution of uncorrected refractive error to blindness and less severe visual impairment from a D mortality stratum sub-region (SEARO D) were available, data from AFRO E used for AFRO D because of higher likelihood of similarities between the two sub-regions from Africa.
  5. §Data from WPRO A used for AMR A and EURO A because of similar mortality stratum and high development stage of these sub-regions; as data from the qualifying survey from Australia for WPRO A was on a population aged 40 years or more [18], the proportional contribution of uncorrected refractive error to blindness and less severe visual impairment in the 40+ age group was used for the whole population in the absence of data on younger age groups.
  6. ¶Data from SEARO B used for AMR B because of similar mortality stratum for these sub-regions.
  7. #Data from SEARO D used for AMR D and EMRO D because of similar mortality stratum for these sub-regions.
  8. **Data from the qualifying survey from Lebanon for EMRO B suggested that approximately 50% of those with less severe visual impairment had their vision improved to 6/18 or better with pinhole [11]; due to the approximate nature of this estimate, we used a conservative estimate of 45% contribution of uncorrected refractive error to less severe visual impairment for this sub-region.
  9. ††Data from EURO B1 used for EURO B2 and EURO C because of similarities among these sub-regions that are made up predominantly of the former Soviet Bloc countries.
  10. ‡‡Data from the qualifying survey from Malaysia for SEARO B suggested that 56.1% of the less severe visual impairment was due to uncorrected refractive error including aphakia [13]; as this was higher than in any other qualifying survey, in order to avoid use of extreme estimates we used a conservative estimate of 45% contribution of uncorrected refractive error to less severe visual impairment for this sub-region.
  11. §§For SEARO D sub-region, of the two qualifying surveys on all age group populations (Table 2), the lower proportional contribution of uncorrected refractive error to blindness and less severe visual impairment was used for this region.
  12. ¶¶Data from the qualifying survey from China for WPRO B1 on a population aged 50 years or more suggested 12.4% contribution of uncorrected refractive error to blindness, and these data for less severe visual impairment were not available [19]; as data from India suggest that the proportional contribution of uncorrected refractive error to blindness is relatively higher when younger age groups are included since blindness due to large uncorrected natural refractive errors sets in at an earlier age [14, 22], and because populations of Chinese origin have the highest rates of myopia [23-25], we estimated 16% and 50% contributions of uncorrected refractive error to blindness and less severe visual impairment, respectively, in the population of all age groups for WPRO B1; data from WPRO B1 used for WPRO B2 because of similar populations in these two sub-regions; relatively lower contribution of uncorrected refractive error to visual impairment assumed for WPRO B3 than in WPRO B1 or B2 because of the predominantly native populations in WPRO B3 that may possibly have a relatively lower burden of refractive error.