1. 녹내장 conference The Tajimi Study
Ap.이나영/R3 정경인/R2 공석준

2. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Introduction
Glaucoma : the second or third leading cause of visual loss worldwide
Primary open-angle glaucoma (POAG)
: most common type of glaucoma in many population-based prevalence studies
 1. prevalence rates differ among studies from 0.5% to 8.8%
2. racial variation in the prevalence of glaucoma also has been reported
Purpose
To assess the prevalence of primary open-angle glaucoma (POAG) and its association with intraocular pressure (IOP) in Tajimi City in central Japan
Design
A cross-sectional epidemiologic study in a defined population.

3. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Study Population
Population-based prevalence survey of glaucoma among residents aged 40 years or older in Tajimi City
Conducted from September 2000 ~ October 2001
Simple random sampling without stratification was used to select 4000 subjects from the 54,165 residents

4. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Screening Examination
Interview on medical history, including past ocular disease
Height, weight, blood pressure
Ophthalmic examinations
- Central corneal thickness (CCT)
- Refraction
- Visual acuity
- Slit-lamp biomicroscopic examination
- Evaluation of angle width (van Herick method)
- IOP measurement (Goldmann applanation tonometry 3 times
 the median value was adopted)
- Fundus examination & photograph
- Visual field test (Frequency Doubling Technology (FDT) screener)

5. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Definitive Examination
When the subject was suspected of having
any ocular diseases
Ophthalmic examinations
- Slit-lamp biomicroscopic examination
- Applanation tonometry
- Visual field test (Humphrey Field Analyzer 30-2 SITA Standard program)
- Gonioscopy
- Optic nerve head evaluation using a Goldmann 2-mirror lens
- Gonioscopy showed no contraindications
 pupil was dilated  then stereoscopic disc photographs, indirect
ophthalmoscopy
(gonioscopy revealed a narrow angle  carried out with the pupil undilated)

6. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Evaluation of the Optic Disc and Nerve Fiber Layer Defect
Rim border : determined based on shadows, gradations of color , texture, and the course of the blood vessels
Vertical cup-to-disc ratio and rim width were evaluated by 0.05-units using a ruler
Nerve fiber layer defect : considered to be suggestive of glaucoma
1. Its width at the disc edge was larger than a major retinal vessel
2. Diverging in an arcuate or wedge shape
Evaluation of Visual Field
Results of the Humphrey Field Analyzer 30-2 SITA Standard program
Carried out for eyes excluding only those apparently unreliable
((fixation loss > 50%, false-positive and false-negative > 50%)
Abnormal visual field data : At least 1 abnormal hemifield
Abnormal hemifield : pattern deviation probability plot  cluster of 3 or more nonedge contiguous points having sensitivity with a probability  less than 5% in the upper or lower hemifield and in 1 of these with a probability of less than 1%.

7. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Diagnosis
Ocular hypertension : IOP exceeding 21 mmHg in at least 1 eye
no ocular findings suggesting any type of glaucoma

8. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Results
Of the selected 4000 subjects, overall number of participants was 3021 (78.1%)
Of the 3021 subjects 1051 subjects underwent definitive examination

9. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Results
The prevalence of POAG and ocular hypertension is summarized
in Table 5. The number of POAG subjects was 119. Of these,
104 patients were diagnosed with category 1 criteria, and 15 were
diagnosed with category 2 criteria. Sixty-three subjects were diagnosed
as POAG suspects. The age-adjusted prevalence of POAG
was 3.9%, and the 95% CI was 3.2% to 4.6%. The prevalence rates
of POAG in the male and female subjects were 4.1 (95% CI,
3.0%–5.2%) and 3.7% (95% CI, 2.8%–4.6%), respectively. The
prevalence of POAG, including POAG suspects, was 6.0% (95%
CI, 5.1%–6.8%). The prevalence of ocular hypertension defined as
IOP more than 21 mmHg was 0.8% (95% CI, 0.5%–1.1%).
The prevalence of POAG with IOP of 21 mmHg or less without
glaucoma medication both in screening and definitive examinations
in both eyes (excluding subjects who were previously diagnosed
with POAG with high IOP) was 3.6% (95% CI, 2.9%–
4.3%), whereas the prevalence of POAG with IOP of more than 21
mmHg was 0.3% (95% CI, 0.1%–0.5%). By including POAG
suspect, the overall prevalence of POAG and its suspect with IOP
of 21 mmHg or less rose to 5.7% (95% CI, 4.8%–6.5%), but the
prevalence of POAG with IOP more than 21 mmHg remained
unchanged (0.3%; 95% CI, 0.1%–0.5%).

10. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Results
The prevalence of POAG increased with age from 2.0% for those aged 40 to 49 years to 7.6% for those aged 70 years and older

11. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Results
Right eye
Left eye
Mean IOP of all the subjects in screening exam
14.6±2.7 mmHg
14.5±2.7 mmHg
Mean IOP of the subjects with POAG
15.4±2.8 mmHg
15.2±1.8 mmHg
Mean IOP of the nonglaucomatous subjects
14.5±2.5 mmHg
14.4±2.6 mmHg
Figure 1. Intraocular pressure (IOP) distribution in the right eyes of all the subjects who participated and the subjects with primary open-angle glaucoma(POAG). The prevalence of POAG in the subjects with each IOP level also is shown
The prevalence of POAG was high in the subjects with high IOP.

12. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Results
No significant intergroup difference
Except that only the mean CCT of left eyes with ocular hypertension was significantly thicker than that of nonglaucoma eyes
Central corneal thickness (CCT) was compared among those
with POAG with IOP of 21 mmHg or less and those with POAG
with IOP more than 21 mmHg, ocular hypertension, and nonglaucoma
subjects (Table 7).

13. 1. The Prevalence of Primary Open-Angle Glaucoma in Japanese
Discussion
A finding of particular interest in this study
 high prevalence of POAG (3.9%) in this population
(Previous reports : suggested a higher prevalence of POAG in black populations <about 1.8%> compared with white, Hispanic, Asian populations)
Another notable finding of this survey
 the low average IOP in subjects with POAG
(POAG with IOP ≤ 21 mmHg : 3.6% > POAG with IOP > 21 mmHg : 0.3%)
 do not mean that the IOP value had no relation to POAG
(Average IOP in POAG subjects was still higher than that in nonglaucoma
subjects, and its prevalence was high in the subjects with high IOP)
The CCT in POAG patients showed no significant difference from that in nonglaucoma subjects
Usefulness of IOP measurement is limited in screening POAG, particularly in Japanese
Involvement of factors other than high IOP in the development of POAG

14. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Introduction
Primary angle-closure glaucoma (PACG) and primary angle closure (PAC)
1. More common in East Asian countries than in Western countries
2. PACG often results in bilateral blindness, develops in an age-dependent manner, is more prevalent in women
3. Majority of PAC is chronic and asymptomatic
 important to detect the disease early in its course
Secondary glaucoma (SG)
1. Results from numerous ocular or systemic disorders
(ex. uveitis, diabetic retinopathy, central retinal vein occlusion)
2. Poor response to ocular hypotensive agents or filtering surgery in late stage
 early detection is important
Purpose
To determine the prevalence of PACG, SG, and all glaucoma in a Japanese population as a part of the Tajimi Study

15. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Diagnosis of Glaucomas
When a participant could not complete the VF testing and optic disc was not visible
1. if the VA was 20/400 and
IOP ≥ 23 mmHg
2. or if the participant had a
history of glaucoma surgery
 category 3

16. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Diagnosis of Glaucomas
PAC
PACG or suspected PACG
: Diagnosed as PAC and glaucoma (category 1, 2, or 3) or suspected glaucoma
Main
criteria
At least one eye having a narrow angle of grade 2 or less by Shaffer’s classification without other ocular findings that could have caused narrowing of the angle 1
IOP > 21 mmHg 2
Peripheral anterior synechia reaching the scleral spur or beyond 3
< 90° of visibility of the pigmented trabecular meshwork in the primary position 4
Evidence of a history of an acute IOP rise including the presence of iris atrophy, glaukomflecken, dilated nonreactive pupil, or a certified medical record of the subject having PAC
A diagnosis of PAC was made when the following
criteria were met: at least one eye having a narrow angle of grade
2 or less by Shaffer’s classification without other ocular findings
that could have caused narrowing of the angle, and the existence of
one or more of the following 4 conditions: IOP 21 mmHg; a
peripheral anterior synechia reaching the scleral spur or beyond;
90° of visibility of the pigmented trabecular meshwork in the
primary position; and evidence of a history of an acute IOP rise,
including the presence of iris atrophy, glaukomflecken, dilated
nonreactive pupil, or a certified medical record of the subject
having PAC

17. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Diagnosis of Glaucomas
Secondary glaucoma and suspected SG 1
Positive history and/or ocular findings of intraocular inflammation 2
The presence of iris or angle neovascularization 3
Presence of exfoliation materials on the iris margin or the lens surface 4
Or other abnormal ocular findings that could cause prior or current IOP elevation 5
Glaucoma (category 1, 2, or 3) or suspected glaucoma

18. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Diagnosis of Glaucomas
Early-onset developmental glaucoma and suspected cases 1
Developmental anomaly of the chamber angle that may cause IOP elevation 2
Characteristic corneal changes such as diameter enlargement or Haab’s striae 3
And/or related ocular anomalies such as seen in Axenfeld–Rieger syndrome, aniridia 4
Glaucoma (category 1, 2, or 3) or suspected glaucoma

19. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Results
Prevalences of PACG and suspected PACG
1. Prevalence significantly increased with age
2. Did not significantly differ between women and men
PAC including PACG and suspected PACG
2. Significantly differ between women and men
Central corneal thicknesses of both PACG and suspected PACG
: 526±40 µm (right eye) and 530±39 µm (left eye)
Tables 1 and 2 show age-specific prevalences of PACG and
PAC. Overall prevalences of PACG and suspected PACG were
0.6% (95% CI, 0.4%–0.9%) and 0.2% (95% CI, 0.1%–0.4%),
respectively. The prevalence significantly increased with age
(P for PACG and P for PACG and suspected
PACG, linear regression analysis) but did not significantly differ
between women and men (P for PACG and P
for PACG and suspected PACG, chi-square test). The prevalence
of PAC including PACG and suspected PACG was 1.3% (95% CI,
0.9%–1.7%), and that of PAC excluding PACG and suspected
PACG was 0.5% (95% CI, 0.3%–0.7%). The prevalence of PAC
including PACG and suspected PACG significantly increased with
age (P0.0001, linear regression analysis). Furthermore, a significant
difference was observed in the prevalence of PAC including
PACG and suspected PACG between women and men (P
0.0028, chi-square test). There were 19 cases of PACG, with 11
being diagnosed with category 1 criteria, 2 with category 2 criteria,
and the remaining 6 with category 3 criteria. No cases showed
gonioscopic findings suggestive of plateau iris syndrome. Central
corneal thicknesses of both PACG and suspected PACG averaged
52640 m in the right eye and m in the left eye.

20. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Results
Prevalence of SG and suspected SG, excluding exfoliation glaucoma
1. Prevalence significantly increased with age
2. Did not significantly differ between women and men
Of the 12 patients with SG or suspected SG
: uveitis (8), ocular trauma (2), iris and angle neovascularization (2)
The prevalence of SG excluding exfoliation glaucoma was
0.3% (95% CI, 0.1%–0.5%; Table 3). The prevalence of suspected
SG was 0.1% (95% CI, 0.0%–0.2%; Table 3). The prevalence
significantly increased with age (P for SG and P
for SG and suspected SG, linear regression analysis) but
did not significantly differ between women and men (P 1.0 for
SG and P for SG and suspected SG, chi-square test).
Numbers of SG and suspected SG cases were 9 and 3, respectively.
Of the 12 patients with SG or suspected SG, 8 had uveitis, 2 had
ocular trauma, and 2 had iris and angle neovascularization.

21. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Results
Prevalence of confirmed and suspected exfoliation glaucoma
(Defined as the presence of exfoliation materials on the iris margin or the lens surface and IOP elevation, and glaucoma (category 1, 2, or 3) or suspected glaucoma)
1. Prevalence significantly increased with age
2. Did not significantly differ between women and men
Prevalences of exfoliation glaucoma and suspected cases were 0.2% (95% CI,
0.0%–0.3%) and 0.1% (95% CI, 0.0%–0.2%), respectively. The
prevalence significantly increased with age (P for exfoliation
glaucoma and P for exfoliation glaucoma and
suspected cases, linear regression analysis) but did not significantly
differ between women and men (P for exfoliation
glaucoma and P for exfoliation glaucoma and suspected
cases, chi-square test).

22. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Results
Based on the present and previous data,24 the prevalence of all
glaucoma (categories 1, 2, and 3) in Tajimi was calculated to be
5.0% (95% CI, 4.2%–5.8%), and that including suspected cases
was 7.5% (95% CI, 6.5%–8.4%). Table 6 shows the standardized
prevalence of glaucoma and suspected cases.

23. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Discussion
Prevalences of PAC including PACG and suspected PACG, and PACG alone
 1.3% and 0.6%, respectively
Effect of age : PAC including PACG and suspected PACG &
PACG and suspected PACG
Effect of gender : PAC including PACG and suspected PACG only
(prevalence of PACG : 3 times higher in females than in males <0.9% vs. 0.3%>
 not statistically significant level because of relatively small numbers of PACG diagnoses )
Compared with other reports conducted in other Asian countries
: the prevalence of PACG or PAC in Japanese tended to be lower,
but was still higher than in Caucasians or African Americans

24. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Discussion
Overall prevalence of SG including exfoliation glaucoma was 0.5%
Exfoliation glaucoma : principal contributor to the prevalence of SG
Detection method in the present study
 Observation of only the pupillary margin and lens surface through undilated pupils
 Exfoliation material may be missed in 10% to 20% of undilated eyes with exfoliation syndrome
 Prevalence of exfoliation glaucoma may have been underestimated in the present study
Uveitic glaucoma is a common type of SG
Pigmentary glaucoma is rarely seen in Japan

25. 2. Prevalence of Primary Angle Closure and Secondary Glaucoma in a Japanese Population
Discussion
Early-onset developmental or congenital glaucoma was not found
1. Relatively small number of subjects
(Early-onset developmental or congenital glaucoma prevalence
: 1 of to births)
2. Life expectancy, expected to be shorter with some forms of congenital
glaucoma with systemic anomalies
Prevalence of POAG,PACG, SG increased with age significantly.
 Glaucoma is an important health issue in the elderly population
Prevalence of POAG with normal IOP to that of all glaucoma was 72% (3.6%/5.0%) in our population
 High prevalence of normal-tension glaucoma is the most distinctive feature of glaucoma epidemiology in Japanese

26. 3. Risk Factors for Open-Angle Glaucoma in a Japanese Population
Introduction
In Tajimi study
1. Average IOP in POAG patients was 15.2–15.4 mmHg
2. 92% of the patients diagnosed had normal IOP
 Affords a good opportunity to investigate the risk factors for glaucoma other than IOP
We investigated the ocular and systemic parameters of POAG patients
and nonglaucoma subjects to identify the risk factors associated with
POAG in the Tajimi Study population

27. 3. Risk Factors for Open-Angle Glaucoma in a Japanese Population
Subjects and Methods
Ocular parameters
- IOP, myopia, corneal curvature radius, and central corneal thickness
- Myopia : myopic spherical equivalent (SE) of the eye > -1.0 diopter (D).
Low myopia : myopic SE of the eye > -1.0 D to < -3.0 D
Moderate to high myopia : myopic SE of the eye ≥ -3.0 D
Systemic parameters
- Age, gender, body mass index, history of diabetes mellitus, migraine, smoking habit, family history of glaucoma, and history of hypertension

28. 3. Risk Factors for Open-Angle Glaucoma in a Japanese Population
Results
are summarized in Table 1. There was no statistical difference
between POAG patients and controls in corneal curvature radius,
central corneal thickness, gender, body mass index, history of
diabetes mellitus and migraine, smoking habit, and family history
of glaucoma.
The mean ( SD) IOP of POAG eyes was mmHg,
which was higher than that of controls ( mmHg) (P
0.0015). The mean age of POAG patients ( years) was
higher than that of controls ( ) (P0.0001). The other
parameter that differed between groups was a history or presence
of hypertension (P ) and myopia (P ).
Multivariate logistic regression analysis with stepwise selection
of variables demonstrated that IOP, myopia, and age significantly
affected the discrimination between POAG patients and controls
(Table 2). Higher IOP (odds ratio [OR], 1.13 [95% confidence
interval (CI), 1.05–1.21]), myopia (ORs, 1.85 [95% CI, 1.03–3.31]
for low myopia and 2.60 [95% CI, 1.56–4.35] for moderate to
high myopia), and older age (OR, 1.05 [95% CI, 1.04 –1.07]) were
associated with increased risk for having POAG.

29. 3. Risk Factors for Open-Angle Glaucoma in a Japanese Population
Discussion
The majority (92%) of POAG patients diagnosed in the Tajimi Study had IOP within the normal range
 The IOP still identified as a significant risk factor for having POAG together with age and myopia
Myopia was a significant risk factor for POAG
- Odds ratios : 1.85 for low myopia, 2.60 for moderate to high myopia
A report that the association of myopia and glaucoma was strong in glaucoma patients with low IOP (Early Manifest Glaucoma Trial)
: Low average IOP of POAG patients
 One of the reasons that myopia was selected to be a significant risk factor for POAG in the present study
POAG is a disease that develops later in life
 the result that age was a significant risk factor is no surprise at all

30. 3. Risk Factors for Open-Angle Glaucoma in a Japanese Population
Discussion
Family history of glaucoma has been known to be associated with POAG
: In the Tajimi Study, information obtained in the interview with participants about the family history of glaucoma was very limited
 Cannot draw any conclusions concerning the association of family history with POAG
Several limitations in the present analyses
1. Several factors not included in the present analysis but reported to be associated with the development of POAG
(ex. systemic medications,16 other ocular diseases,16 and computer use)
2. The information about some of the factors investigated was not defined thoroughly
(ex. Diagnosis of DM, smoking, and migraine depended entirely on participants’ own reports)
A large number of myopic subjects
Long life expectancy
Significant clinical implications

31. 4. Corneal Thickness and Relating Factors in a Population-Based Study in Japan: The Tajimi Study
Introduction
Central corneal thickness(CCT)
: indicates corneal physiologic health and affects the measurement of IOP
Purpose
To evaluate CCT in a Japanese population and to describe the relationship between CCT and other factors
The subjects were identical to those in the preceding reports from the Tajimi Study

32. 4. Corneal Thickness and Relating Factors in a Population-Based Study in Japan: The Tajimi Study
6,042 eyes of 3,021 subjects were examined (participation rate, 78.1%)
 404 eyes were excluded because reliable CCT data were not obtained

33. 4. Corneal Thickness and Relating Factors in a Population-Based Study in Japan: The Tajimi Study
Results
Average CCT (5638 eyes)
Right eyes (2826 eyes)
Left eyes
(2812 eyes)
Men
Woman
± mm
± mm
± mm
± mm (OD)
0.526 ± mm (OS)
0.516 ±0.032 mm (OD)
0.518 ± mm (OS)
The CCT was significantly thicker in men than in women

34. 4. Corneal Thickness and Relating Factors in a Population-Based Study in Japan: The Tajimi Study
Results
The mean CCT did not differ significantly between 2,671 normal eyes and 69 eyes with POAG regardless of IOP
The Pearson
correlation analyses showed that the CCT was significantly
(P .05) correlated with age (right eyes only), body
height, weight, diastolic blood pressure, systolic blood
pressure (left eyes only), IOP, and radius of corneal
curvature (Table 2). However, because these variables
were correlated with each other, multiple regression analysis
was performed in which CCT was the dependent
variable and the other variables were independent variables.
The results showed only that the gender, IOP, and
corneal curvature were significantly associated with CCT
(P .011). Because the IOP is not responsible for the
CCT, another multiple regression analysis was performed
in which the IOP was excluded from the independent
variables, and the gender, corneal curvature, and weight
were significantly (P .036) associated with the CCT

35. 4. Corneal Thickness and Relating Factors in a Population-Based Study in Japan: The Tajimi Study
Results
Previous population-based studies found a significant relationship between age and CCT
 The current study, found a significant but very weak correlation in only
right eyes in simple correlation analysis (P = .012)
Correlation diminished with multiple regression analyses (P > .2)
In summary
1. Mean CCT in a Japanese population was mm
2. Men had thicker corneas than women
3. CCT was significantly associated with gender, IOP, and corneal curvature
but not with age after adjusting for other factors using multiple regression
analysis

36. 5. Ocular and systemic factors related to intraocular pressure in Japanese adults: the Tajimi study
Introduction
Population-based studies have consistently shown that IOP and age
are the two major risk factors of glaucoma
In the current report , we examined the distribution of IOP and its correlation with other systemic and ocular factors, especially age, in Japanese adults
The influence of factors reportedly correlating with IOP
: such as blood pressure, body mass index (BMI), CCT, corneal curvature, refraction, a history of diabetes or smoking, was corrected by multiple regression analysis

37. 5. Ocular and systemic factors related to intraocular pressure in Japanese adults: the Tajimi study
Results
Of 6042 eyes (3021 participants), 860 eyes were excluded for various reasons that might have affected the results of IOP measurement
As a consequence, 5182 eyes were included in the current analysis
Of 6042 eyes
(3021 participants), 860 eyes were excluded for various reasons
that might have affected the results of IOP measurement,
including the presence of glaucoma or the suspicion of glaucoma
in at least one eye (460 eyes of 230 subjects) (table 1).

38. 5. Ocular and systemic factors related to intraocular pressure in Japanese adults: the Tajimi study
Results
The IOP averaged mm Hg in men and mm Hg in woman with no significant intergender difference
The demographic data from the 2597 participants of whom at
least the right eye was eligible are summarised in table 2.

39. 5. Ocular and systemic factors related to intraocular pressure in Japanese adults: the Tajimi study
Results
Between IOP and age, a weak but significant correlation was
found in both males (Rs=20.067, p=0.022) and females
(Rs=20.056, p=0.032). As for the results of multiple
regression analyses (R2=0.09), age was also negatively correlated
with IOP (non-standardised beta (B)=20.020/year,
PCC=20.077, p=0.0001) (table 3). In addition, a higher BMI
(Rs=0.14, p,0.001; B=0.084/BMI, PCC=0.106, p,0.0001),
higher mean blood pressure (Rs=0.144, p,0.001; B=0.022/
mm Hg, p=0.121, p,0.0001), history of diabetes (PCC=0.062,
p=0.0019), thicker central cornea (Rs=0.167, p,0.001;
B=0.014/mm, PCC=0.175, p,0.0001), higher myopia
(Rs=20.090, p,0.001; B=20.055/dioptre, PCC=20.057,
p=0.0043) and a steeper corneal curvature (Rs=20.055,
p=0.005; B=20.72/mm, PCC=20.074, p=0.0002) were
significantly correlated with higher IOP

40. 5. Ocular and systemic factors related to intraocular pressure in Japanese adults: the Tajimi study
Discussion
In the current study, IOP measured by applanation tonometry averaged
14.5 mm Hg in a non-glaucomatous Japanese population aged 40 or older
 this value was lower than that in normal-tension glaucoma patients
(15.2 mm Hg) in the Tajimi Study
When compared with the mean IOP measured by
applanation tonometry in population-based studies from other
countries, the mean IOP of 14.5 mm Hg in the current study is
lower than those in the Baltimore Eye Survey (17.2 mm Hg in
whites, 16.0 mm Hg in blacks),1 the Beaver Dam Eye Study
(15.3 mm Hg in men, 15.5 mm Hg in women),6 and the
Barbados Eye Study (17.8 mm Hg);7 is similar to those in the
Rotterdam Study (14.6 mm Hg),12 the Egna-Neumarkt Study
(15.1 mm Hg in men, 14.9 mm Hg in women),3 the Tehran Eye
Study (14.5 mm Hg),8 the West Bengal Glaucoma Study
(14 mm Hg)13 and a Bangladesh study (15 mm Hg);14 and is
higher than that in a Thailand study (13.3 mm Hg)15 (table 4).

41. 5. Ocular and systemic factors related to intraocular pressure in Japanese adults: the Tajimi study
Discussion
The current report first confirmed the negative correlation between age and IOP in a Japanese adult population
- Many previous studies in the USA and Europe : IOP increased with age
- In East Asia (Taiwan and China) : IOP decreased with age(age of 65 and older)
 It is possible that the negative correlation between age and IOP is a common characteristic at least in people older than 65 years in East Asia
 the current study first demonstrated a negative correlation in a population including the younger generation (ex, 40 years or older)
In many previous studies, a positive correlation between IOP and blood pressure was found
- This trend also was confirmed in the current study
- Increased blood pressure  increased ciliary artery pressure  increasing the ultrafiltration of the aqueous humour  increasing IOP

42. 5. Ocular and systemic factors related to intraocular pressure in Japanese adults: the Tajimi study
Discussion
Positive correlations between IOP and BMI was seen in the current study
: Obese subjects elevated orbital pressure due to excess fat high episcleral venous pressure  decreased outflow facility
The presence of self-reported diabetes also was positively associated with IOP in the current study
: but, diabetes was not associated with the presence of POAG
Thicker cornea, more myopia and steeper corneal curvature were correlated with a higher IOP
A positive correlation between IOP and myopia was found first as a population-based study