title: The prevalence of primary open-angle glaucoma in Japanese: the Tajimi Study.
abstract: OBJECTIVE
  To assess the prevalence of primary open-angle glaucoma (POAG) and its association with intraocular pressure (IOP) in Tajimi City in central Japan.
  
  
  METHODS
  A cross-sectional epidemiologic study in a defined population.
  
  
  METHODS
  Subjects randomly selected from the population older than 40 years in Tajimi City.
  
  
  METHODS
  Each subject underwent a screening examination comprised of an interview and ophthalmic examinations, including measurement of IOP by a Goldmann applanation tonometer, central corneal thickness (CCT), slit-lamp examination, fundus photography, and a screening visual field test using frequency doubling technology. When ocular diseases were suspected, the subjects were referred for definitive examination. During the definitive examination, slit-lamp examination, IOP measurement, a visual field test using Humphrey Field Analyzer 30-2 SITA Standard program (Humphrey Instruments, San Leandro, CA), optic disc and fundus examination, and gonioscopy were performed and stereoscopic disc photographs were obtained. A diagnosis of glaucoma was made based on optic disc appearance, perimetric results, and other ocular findings.
  
  
  METHODS
  Prevalence of POAG, mean IOP, and mean CCT.
  
  
  RESULTS
  Of 3870 eligible people, 3021 (78.1%) participated in the study. The estimated prevalence of POAG in the population older than 40 years was 3.9% (95% confidence interval [CI]), 3.2%-4.6%). The prevalence of cases of POAG with IOP levels of 21 mmHg or less was 3.6% (95% CI, 2.9%-4.3%), whereas the prevalence for those with IOP levels of more than 21 mmHg was 0.3% (95% CI, 0.1%-0.5%). The average IOP for eyes with POAG was 15.4+/-2.8 (standard deviation) in the right eye (n = 115) and 15.2+/-2.8 mmHg in the left eye (n = 115), which was significantly higher than that of nonglaucoma subjects (14.5+/-2.5 in the right eye; n = 2759; P = 0.0004; and 14.4+/-2.6 mmHg in the left eye; n = 2757; P = 0.0026). The mean CCT of POAG eyes with IOP levels of 21 mmHg or less was 518+/-29 (n = 109) in the right eye and 519+/-29 microm (n = 110) in the left eye, levels that were not significantly different from that of nonglaucoma eyes (520+/-32 microm [n = 2690]; and 522+/-32 microm [n = 2692]; P>0.05).
  
  
  CONCLUSIONS
  The prevalence of POAG in this population was 3.9%. In 92% patients with POAG, the IOP was 21 mmHg or less.
authors.affiliation: Department of Ophthalmology, Tajimi Municipal Hospital, Tajimi, Japan.
authors.forename: Aiko
authors.initials: A
authors.lastname: Iwase
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Makoto
authors.initials: M
authors.lastname: Araie
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Haruki
authors.initials: H
authors.lastname: Abe
authors.forename: Shiroaki
authors.initials: S
authors.lastname: Shirato
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Kuwayama
authors.forename: Hiromu K
authors.initials: HK
authors.lastname: Mishima
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shimizu
authors.forename: Goji
authors.initials: G
authors.lastname: Tomita
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Inoue
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kitazawa
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D016021:Epidemiologic Studies; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D007429:Intraocular Pressure; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D017678:Sex Distribution; D014792:Visual Acuity; D058609:Visual Field Tests; D014794:Visual Fields