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Blindness survey methods: Response from Sudan study authors

We thank the authors [1,2] for the two perspectives on our articles [3,4]. Our study estimated the prevalence of blindness in Mankien at 4%, which Kuper and Gilbert describe as being “beyond the range” of the studies reviewed by Pascolini et al. [5]. The review did not include any studies from the ten states that compose southern Sudan. The nearest surveys reported were conducted in 1998 in Al-Ginena province of Southern Darfur—which is within the 16 northern states of Sudan governed from Khartoum, and was not directly affected by the war in the south. The Al-Ginena studies show a blindness prevalence of 3.2% in all ages [6,7]. Yet despite the geographical proximity, two decades of civil war in the south were accompanied by the absence of a health infrastructure, and no preventive health services to speak of, which makes southern Sudan unique. Comparisons with other parts of Sudan or with other countries are probably not justified or meaningful.


Ngondi, J., Ole-Sempele, F., Onsarigo, A., Matende, I., Baba, S., Reacher, M., ... Emerson, PM. (2007). Blindness survey methods: Response from Sudan study authors. PLoS Medicine, 4(2), e86. https://doi.org/10.1371/journal.pmed.0040086