title: Impact of environmental pollution on the eye.
abstract: OBJECTIVE
  To study the effect of environmental toxins on the ocular surface in persons travelling through highly polluted areas of the metropolis of Delhi.
  
  
  METHODS
  A total of 500 apparently healthy volunteers recruited from the metropolis of Delhi were examined to establish the frequency of ocular surface disorders. All subjects underwent a slit-lamp examination, tear break-up time (BUT) test, Rose Bengal test, Schirmer's test and tear lysozyme level test.
  
  
  RESULTS
  Subjects in the study group had significantly higher levels of ophthalmic symptoms compared to the control group. In all, 105 (42%) and 125 (50%) subjects in the study group compared to 50 (20%) and 65 (26%) in the control group complained of redness and irritation (p < 0.05). There was no significant difference in visual acuity (VA) between the two groups, with best corrected VA being 6/9 or better in 92% of the study group and 96% of the control group. The average (+/-standard deviation) Schirmer's test result was 13.42+/-6.67 mm in the study group compared to 15.95+/-6.14 mm in the control group. This difference was statistically significant. The BUT was also significantly lower in the study group (12.97+/-6.12 seconds) compared to the control group (19.23+/-5.70 seconds) (p < 0.001). The Rose Bengal test and tear lysozyme activity did not show any significant difference between the two groups.
  
  
  CONCLUSIONS
  According to our study, environmental conditions appear to have a very significant effect on the ocular surface. There were very high levels of subclinical ocular surface changes among persons travelling in highly polluted areas.
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004787:Environmental Pollution / Q000009:adverse effects*; D005123:Eye / Q000473:pathology*; D005128:Eye Diseases / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013666:Tears / Q000378:metabolism; D014792:Visual Acuity