title: The epidemiology of low vision and blindness associated with trichiasis in southern Sudan.
abstract: BACKGROUND
  We investigated vision status associated with trachomatous trichiasis (TT) and explored age-sex patterns of low vision and blindness associated with trichiasis in Mankien district of southern Sudan where trachoma prevention and trichiasis surgery were absent.
  
  
  METHODS
  A population based survey was undertaken and eligible persons underwent eye examination. Visual acuity (VA) was tested using Snellen E chart and persons with TT identified. Vision status was defined using the WHO categories of visual impairment based on presenting VA: normal vision (VA > or = 6/18 in better eye); low vision (VA < 6/18 but > or = 3/60 in better eye); and blindness (VA < 3/60 in better eye). An ordinal logistic regression model was fitted and age/sex specific distribution of vision status predicted.
  
  
  RESULTS
  Overall 341/3,567 persons examined had any TT. Analysis was based on 319 persons, 22 persons were excluded: 20 had both TT and cataract; and 2 had missing VA data. Of the 319 persons: 158(49.5%) had trichiasis-related corneal opacity (CO); bilateral TT and bilateral CO were found in 251(78.7%) and 110 (34.5%), respectively; 146 (45.8%) had low vision or blindness; the ratio of low vision to blindness was 3.2:1; and no sex differences were observed. In our model the predicted distribution of vision status was: normal vision, 53.9% (95% CI 50.9-56.9); low vision, 35.3% (95% CI 33.3-37.2); and blindness, 10.9% (95% CI 9.7-12.0).
  
  
  CONCLUSIONS
  We have reported severe trichiasis and high prevalence of vision loss among persons with trichiasis. Our survey showed that almost 1 in 20 of the entire population suffered low vision or blindness associated with trachoma. The need for trichiasis surgery, trachoma prevention services, and rehabilitation of the blind is acute.
authors.affiliation: Department of Public Health and Primary care, Institute of Public Health, University of Cambridge, Cambridge, UK. jn250@cam.ac.uk
authors.forename: Jeremiah
authors.initials: J
authors.lastname: Ngondi
authors.forename: Mark
authors.initials: M
authors.lastname: Reacher
authors.forename: Fiona
authors.initials: F
authors.lastname: Matthews
authors.forename: Francis
authors.initials: F
authors.lastname: Ole-Sempele
authors.forename: Alice
authors.initials: A
authors.lastname: Onsarigo
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Matende
authors.forename: Samson
authors.initials: S
authors.lastname: Baba
authors.forename: Carol
authors.initials: C
authors.lastname: Brayne
authors.forename: Paul
authors.initials: P
authors.lastname: Emerson
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001766:Blindness / Q000453:epidemiology* / Q000209:etiology*; D002648:Child; D002675:Child, Preschool; D005141:Eyelid Diseases / Q000150:complications* / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006201:Hair Diseases / Q000150:complications* / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012720:Severity of Illness Index; D017678:Sex Distribution; D013397:Sudan / Q000453:epidemiology; D014141:Trachoma / Q000150:complications*; D015354:Vision, Low / Q000453:epidemiology* / Q000209:etiology*