title: Cortical lenticular opacification: distribution and location in a longitudinal study.
abstract: OBJECTIVE
  To examine the distribution of cortical opacification of the lens by lens quadrant in a longitudinal study.
  
  
  METHODS
  In 1990, a follow-up assessment of a cohort of Chesapeake Bay watermen, initially studied in 1985, was performed. Four hundred thirty-seven subjects (834 eyes) had gradable cortical photographs for at least one eye in both 1985 and 1990. Cortical photographs were graded by both estimating total area and determining the quadrant with the greatest degree of cortical opacification.
  
  
  RESULTS
  The prevalence and severity of cortical opacification increased with age with a high degree of concordance (84%) between eyes. For the 47 eyes with cortical opacification > or = 1/8 at baseline, the principal locations of opacification were: inferonasal 63.8%, inferotemporal 17.0%, superonasal 6.4%, and superotemporal 12.8% (P < 0.001, compared with equal distribution by quadrant). Five-year development of new cortical opacification and five-year progression of existing cortical opacification showed even greater preferential occurrence in the inferonasal quadrant of the lens.
  
  
  CONCLUSIONS
  In this population, the inferonasal quadrant of the lens is the principal site of cortical opacification in both cross-sectional and longitudinal assessment. This finding is consistent with the hypothesis that sunlight exposure is a significant risk factor for cortical opacification.
authors.affiliation: Dana Center for Preventive Ophthalmology, Wilmer Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: O D
authors.initials: OD
authors.lastname: Schein
authors.forename: S
authors.initials: S
authors.lastname: West
authors.forename: B
authors.initials: B
authors.lastname: Muñoz
authors.forename: S
authors.initials: S
authors.lastname: Vitale
authors.forename: M
authors.initials: M
authors.lastname: Maguire
authors.forename: H R
authors.initials: HR
authors.lastname: Taylor
authors.forename: N M
authors.initials: NM
authors.lastname: Bressler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000453:epidemiology / Q000209:etiology / Q000473:pathology*; D015331:Cohort Studies; D005500:Follow-Up Studies; D006801:Humans; D007904:Lens Cortex, Crystalline / Q000473:pathology* / Q000528:radiation effects; D008137:Longitudinal Studies; D008297:Male; D008396:Maryland / Q000453:epidemiology; D008875:Middle Aged; D010781:Photography; D015995:Prevalence; D011832:Radiation Injuries / Q000453:epidemiology / Q000209:etiology / Q000473:pathology; D012307:Risk Factors; D014466:Ultraviolet Rays / Q000009:adverse effects