녹내장 conference The Tajimi Study 2009.12.4 Ap.이나영/R3 정경인/R2 공석준

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.

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

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)

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)

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%.

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

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

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%).

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

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.

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).

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

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

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

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

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

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

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 (P0.0001 for PACG and P0.0001 for PACG and suspected PACG, linear regression analysis) but did not significantly differ between women and men (P 0.1162 for PACG and P 0.1023 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 53039 m in the left eye.

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 0.0034 for SG and P 0.0014 for SG and suspected SG, linear regression analysis) but did not significantly differ between women and men (P 1.0 for SG and P 0.8618 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.

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 0.0183 for exfoliation glaucoma and P 0.0073 for exfoliation glaucoma and suspected cases, linear regression analysis) but did not significantly differ between women and men (P 0.2442 for exfoliation glaucoma and P 0.4904 for exfoliation glaucoma and suspected cases, chi-square test).

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.

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

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

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 10 000 to 100 000 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

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

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

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 15.22.9 mmHg, which was higher than that of controls (14.42.6 mmHg) (P 0.0015). The mean age of POAG patients (63.812.0 years) was higher than that of controls (57.811.6) (P0.0001). The other parameter that differed between groups was a history or presence of hypertension (P 0.009) and myopia (P 0.044). 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.

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

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

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

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

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 0.521 ± 0.032 mm 0.520 ± 0.032 mm 0.522 ± 0.032 mm 0.524 ± 0.031 mm (OD) 0.526 ± 0.031 mm (OS) 0.516 ±0.032 mm (OD) 0.518 ± 0.031 mm (OS) The CCT was significantly thicker in men than in women

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

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 0.521 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

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

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).

5. Ocular and systemic factors related to intraocular pressure in Japanese adults: the Tajimi study Results The IOP averaged 14.58 mm Hg in men and 14.49 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.

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

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).

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

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