title: Primary open-angle glaucoma in a population associated with high prevalence of primary angle-closure glaucoma: the Kumejima Study.
abstract: OBJECTIVE
  To evaluate the prevalence of and risk factors for primary open-angle glaucoma (POAG) in a rural population of southwestern Japan.
  
  
  METHODS
  Population-based cross-sectional study.
  
  
  METHODS
  All residents 40 years of age and older in Kumejima, Okinawa, Japan.
  
  
  METHODS
  Of the eligible 4632 residents 40 years of age and older, 3762 subjects (participant rate, 81.2%) underwent screening examinations, including visual acuity (VA) measurement, slit-lamp examination, Goldmann applanation tonometry, gonioscopy, undilated stereoscopic fundus photographs, autorefractometry, noncontact specular microscopy, pachymetry, and visual field (VF) testing using frequency-doubling technology. If glaucoma or other related ocular disorders were suspected, subjects were referred for definitive examinations including VF testing with the Humphrey Field Analyzer. The diagnosis of POAG was based on the criteria of the International Society for Geographical and Epidemiological Ophthalmology.
  
  
  METHODS
  Prevalence and risk factors of POAG.
  
  
  RESULTS
  The prevalence of POAG was 4.0% (95% confidence interval [CI], 3.4%-4.7%); 82% of patients had an intraocular pressure (IOP) less than 22 mmHg, resulting in a prevalence of 3.3% (95% CI, 2.8%-3.9%). Because of POAG, 3 subjects had a VA worse than 20/400 in only 1 eye, and 1 subject had VA loss of worse than 20/400 bilaterally. The average IOP values (mean ± standard deviation) were 14.9 ± 3.2 and 14.6 ± 3.3 mmHg in the right and left eyes, respectively; the IOP values were higher in patients with POAG (15.4 ± 3.3 and 15.2 ± 3.3 mmHg, respectively) than in subjects without glaucoma (14.8 ± 3.1 and 14.4 ± 3.1 mmHg, respectively; P<0.045, Student t test). Multivariate analysis showed that male gender (P = 0.003), older age (P<0.001), higher IOP (P<0.001), longer axial length (P<0.001), and thinner central cornea (P = 0.006) were associated with POAG.
  
  
  CONCLUSIONS
  High prevalence rates of POAG (4.0%) and POAG with normal IOP levels (3.3%), which were comparable with those on the Japanese mainland, were found in a southwestern rural island of Japan, where the prevalence of primary angle-closure glaucoma (previously reported as 2.2%) was considerably higher than on the Japanese mainland (0.6% in the Tajimi Study) or other countries. The risk factors for POAG included male gender, older age, higher IOP, myopia, and a thinner cornea.
authors.affiliation: Department of Ophthalmology, University of the Ryukyus, Graduate School of Medicine, Okinawa, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Department of Ophthalmology, University of the Ryukyus, Graduate School of Medicine, Okinawa, Japan. Electronic address: sshoichi@med.u-ryukyu.ac.jp.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Sawaguchi
authors.affiliation: Department of Ophthalmology, Tajimi Iwase Eye Clinic, Gifu, Japan.
authors.forename: Aiko
authors.initials: A
authors.lastname: Iwase
authors.affiliation: Department of Ophthalmology, University of Gifu Graduate School of Medicine, Gifu, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Ophthalmology, Niigata University, Graduate School of Medicine, Niigata, Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Abe
authors.affiliation: Department of Ophthalmology, Toho University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Goji
authors.initials: G
authors.lastname: Tomita
authors.affiliation: Department of Ophthalmology, University of Tokyo Graduate School of Medicine, Tokyo, Japan.
authors.forename: Atsuo
authors.initials: A
authors.lastname: Tomidokoro
authors.affiliation: Department of Ophthalmology, University of Tokyo Graduate School of Medicine, Tokyo, Japan; Kanto Central Hospital of The Mutual Aid Association of Public School Teachers, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Araie
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis / Q000453:epidemiology*; D005902:Glaucoma, Open-Angle / Q000175:diagnosis / Q000453:epidemiology*; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data; D017678:Sex Distribution; D014065:Tonometry, Ocular; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology