The prevalence of primary open-angle glaucoma in Japanese: the Tajimi Study.
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.
Iwase
Aiko
A
Department of Ophthalmology, Tajimi Municipal Hospital, Tajimi, Japan.
Suzuki
Yasuyuki
Y
Araie
Makoto
M
Yamamoto
Tetsuya
T
Abe
Haruki
H
Shirato
Shiroaki
S
Kuwayama
Yasuaki
Y
Mishima
Hiromu K
HK
Shimizu
Hiroyuki
H
Tomita
Goji
G
Inoue
Yoichi
Y
Kitazawa
Yoshiaki
Y
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