title: Subclinically dry eyes in urban Delhi: an impact of air pollution?
abstract: OBJECTIVE
  To study the effects of air pollution on the eyes of persons staying in the metropolis of New Delhi.
  
  
  METHODS
  400 healthy volunteers from within and outside the metropolis of Delhi were investigated for the presence of tear film abnormalities. All persons underwent slitlamp examination to rule out any ocular surface disorder. The tear break-up time (BUT) was assessed along with a Schirmer test and the tear lysozyme activity and the tear pH were determined.
  
  
  RESULTS
  Of the 210 persons staying in the metropolis, 50 (24%) had an abnormal BUT, 14 (6.6%) had an abnormal Schirmer test, and the tear lysozyme activity was found to be low in 12 (5%). In contrast, of those 190 persons living outside the metropolis, only 10 (5.2%) had an abnormal BUT, 4 (2%) had an abnormal Schirmer test, and none had a low lysozyme activity (p < 0.05). None of the persons in either group had significant eye symptoms.
  
  
  CONCLUSIONS
  Tear film abnormalities are present in a large number of people staying within the metropolis of New Delhi who have apparently normal eyes. Air pollution over a long period of time could possibly be associated with their causation.
authors.affiliation: Department of Pharmacology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Suresh K
authors.initials: SK
authors.lastname: Gupta
authors.forename: Viney
authors.initials: V
authors.lastname: Gupta
authors.forename: Sujata
authors.initials: S
authors.lastname: Joshi
authors.forename: Radhika
authors.initials: R
authors.lastname: Tandon
mesh_terms: D000328:Adult; D000397:Air Pollution / Q000009:adverse effects*; D015352:Dry Eye Syndromes / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D009113:Muramidase / Q000378:metabolism; D013666:Tears / Q000502:physiology; D014505:Urban Population
chemical_list: D009113:Muramidase