title: Case-control study of risk factors for acute corneal hydrops in keratoconus.
abstract: To determine risk factors for the development of acute corneal hydrops in keratoconus in the UK in a case-controlled study.
  
  
  
  Between November 2009 and December 2010, we prospectively identified 73 individuals who developed acute corneal hydrops. We then identified 174 controls from nine regions in the UK with keratoconus who had not had hydrops. For cases and controls we recorded demographics and clinical features. Univariate and multivariable logistic regressions were performed to identify risk factors.
  
  
  
  Univariate analysis suggested strong associations between the odds of hydrops and each of vernal keratoconjunctivitis (OR 4.08, 95% CI 1.45 to 11.49, p=0.008), asthma (OR 2.70, CI 1.34 to 5.47, p=0.006), atopic dermatitis (OR 3.13, CI 1.50 to 6.56, p=0.002), learning difficulties (OR 7.84, CI 2.86 to 21.46, p<0.001), previous hydrops (OR 40.2; CI 6.2 to ∞, p<0.001), black ethnicity (OR 2.98, CI 0.98 to 8.99; p=0.05), visual acuity in the worse eye (OR 8.76 CI 3.86 to 19.88; p<0.001) and minimum keratometry of ≥48 D prior to the hydrops (OR 4.91, CI 1.07 to 22.6, p=0.041). The use of a contact lens correction was also found to be associated with the odds of hydrops (OR 0.08; CI 0.03 to 0.19, p<0.001). Multiple variable regression indicated that having vernal keratoconjunctivitis (adjusted OR (AOR) 15, 95% CI 1.30 to 173.7; p=0.03), asthma (AOR 4.92, CI 1.22 to 19.78; p=0.025), visual acuity in worse eye (AOR 4.11, CI 1.18 to 14.32; p=0.026) and a high keratometry value (AOR 4.44, CI 0.85 to 23.18; p=0.077) were independently associated with the odds of hydrops in subjects with keratoconus.
  
  
  
  Some individuals with keratoconus are at high risk of developing acute corneal hydrops. These patients could be managed more aggressively to reduce their risk of developing this complication of their disease.
authors.affiliation: Luton and Dunstable Hospital NHS Foundation Trust, Luton, UK.
authors.forename: Allon
authors.initials: A
authors.lastname: Barsam
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK.
authors.forename: Nic
authors.initials: N
authors.lastname: Brennan
authors.affiliation: Clinical and Diagnostic Oral Sciences, Queen Mary University of London, London, UK.
authors.forename: Harry
authors.identifier: 0000-0002-4662-2994
authors.initials: H
authors.lastname: Petrushkin
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK.
authors.forename: Wen
authors.initials: W
authors.lastname: Xing
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK.
authors.forename: Ana
authors.initials: A
authors.lastname: Quartilho
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK.
authors.forename: Catey
authors.initials: C
authors.lastname: Bunce
authors.affiliation: British Ophthalmic Surveillance Unit, Royal College of Ophthalmologists, London, UK.
authors.forename: Barny
authors.initials: B
authors.lastname: Foot
authors.affiliation: Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, UK.
authors.forename: Nathaniel Knox
authors.initials: NK
authors.lastname: Cartwright
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK.
authors.forename: Anjana
authors.initials: A
authors.lastname: Haridas
authors.affiliation: Nottingham University Hospitals NHS Trust, Nottingham, UK.
authors.forename: Pavi
authors.initials: P
authors.lastname: Agrawal
authors.affiliation: Division of Ophthalmology and Visual Sciences, University of Nottingham, Nottingham, UK.
authors.forename: Hanif
authors.initials: H
authors.lastname: Suleman
authors.affiliation: Royal Liverpool University Hospital, Liverpool, UK.
authors.forename: Sajjad
authors.initials: S
authors.lastname: Ahmad
authors.affiliation: Departement of Ophthalmology, Tennent Institute, Glasgow, Strathclyde, UK.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: MacDonald
authors.affiliation: University Hospital of Wales, Cardiff, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Johnston
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Tuft
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002648:Child; D003315:Cornea / Q000473:pathology*; D003316:Corneal Diseases / Q000453:epidemiology / Q000209:etiology / Q000473:pathology*; D004487:Edema / Q000453:epidemiology / Q000209:etiology / Q000473:pathology*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000150:complications / Q000453:epidemiology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology; D014792:Visual Acuity; D055815:Young Adult
keywords: Cornea; Epidemiology