title: Effect of Allergic Diseases on Keratoconus Severity.
abstract: OBJECTIVE
  To investigate the association between keratoconus (KC) and allergic diseases.
  
  
  METHODS
  In a prospective age- and sex-matched case--control study clinical data of 885 KC patients and 1526 controls were evaluated regarding the presence of various allergic diseases. Severity of KC and ophthalmic parameters of KC patients were compared between KC patients with and without allergic diseases.
  
  
  RESULTS
  The prevalence of allergic diseases was significantly higher in KC patients. KC patients with vernal keratoconjunctivitis (VKC) or allergic conjunctivitis (AC) had significantly thinner and steeper corneas in comparison with non-allergic KC patients. Only VKC and AC were significantly associated with KC severity.
  
  
  CONCLUSIONS
  Patients with VKC or AC were at increased risk of KC. They had more severe KC and should be closely followed up and intensively treated.
authors.affiliation: a Eye Research Center, Farabi Eye Hospital , Tehran University of Medical Sciences , Tehran , Iran.
authors.forename: Mohammad
authors.identifier: http://orcid.org/0000-0001-5774-4607
authors.initials: M
authors.lastname: Naderan
authors.affiliation: a Eye Research Center, Farabi Eye Hospital , Tehran University of Medical Sciences , Tehran , Iran.
authors.forename: Mohammad Taher
authors.identifier: http://orcid.org/0000-0001-7379-6861
authors.initials: MT
authors.lastname: Rajabi
authors.affiliation: b Zarrinbakhsh Eye Clinic , Tehran , Iran.
authors.forename: Parviz
authors.initials: P
authors.lastname: Zarrinbakhsh
authors.affiliation: c School of Medicine , AJA University of Medical Sciences , Tehran , Iran.
authors.forename: Anahita
authors.initials: A
authors.lastname: Bakhshi
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003233:Conjunctivitis, Allergic / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000453:epidemiology / Q000503:physiopathology*; D008297:Male; D015995:Prevalence; D011446:Prospective Studies; D012720:Severity of Illness Index; D055815:Young Adult
keywords: Allergic conjunctivitis; allergic diseases; asthma; atopy; corneal thickness; keratoconus; severity; vernal keratoconjunctivitis