Retinal nerve fibre layer cross-sectional area, neuroretinal rim area and body mass index.

PURPOSE: To examine associations between body mass index, neuroretinal rim area and retinal nerve fibre layer cross-sectional area (RNFLCRA) in a population-based setting. METHODS: The Central India Eye and Medical Study is a population-based study performed in a rural region of Central India. The study included 4711 subjects (aged 30 + years). A detailed ophthalmic and medical examination was performed. Inclusion criteria for this study were an intra-ocular pressure ≤21 mmHg, open anterior chamber angles and an axial length ≤26.5 mm. Neuroretinal rim area and RNFLCRA were measured by confocal laser scanning tomography. RESULTS: The study included 3959 subjects fulfilling the inclusion criteria. Larger neuroretinal rim area (mean: 1.63 ± 0.32 mm(2) ) was significantly (p = 0.004) associated with a higher body mass index after adjusting for larger disc area (p < 0.001), younger age (p < 0.001), lower intraocular pressure (p < 0.001), and hyperopic refractive error (p < 0.001). Larger retinal nerve fibre layer cross-sectional area (mean:1.29 ± 0.39 mm(2) ) was significantly associated with higher body mass index (p = 0.001) after adjusting for younger age (p < 0.001), shorter axial length (p < 0.001), larger optic disc area (p < 0.001), taller body height (p < 0.001) and male gender (p = 0.04). CONCLUSIONS: In a rural Central Indian population, neuroretinal rim area and RNFLCRA as surrogates of the optic nerve fibres were related to a higher body mass index. Because body mass index is associated with cerebrospinal fluid pressure, the higher cerebrospinal fluid pressure may be associated with a larger neuroretinal rim area. It may vaguely point towards an association between cerebrospinal fluid pressure and glaucomatous optic neuropathy.

Pseudoexfoliation: normative data and associations. The Central India Eye and Medical Study.

PURPOSE: To assess the prevalence of pseudoexfoliation (PEX) and its associations in a population-based setting. DESIGN: Population-based, cross-sectional study. METHODS: The Central India Eye and Medical Study included 4711 individuals. All study participants underwent a detailed ophthalmological examination. After medical pupil dilation, PEX was assessed by an experienced ophthalmologist using slit-lamp based biomicroscopy. RESULTS: Slit lamp examination results were available for 4646 (98.6%) study participants with a mean age of 49.3 ± 13.3 years (range: 30-100 years). PEX was detected in 87 eyes (prevalence: 0.95 ± 0.10% (95%CI: 0.75, 1.15) of 69 subjects (prevalence: 1.49 ± 0.18% (95%CI: 1.14, 1.83). PEX prevalence increased significantly (P<0.001) from 0% in the age group of 30-39 years, to 2.85 ± 0.56% in the age group of 60-69 years, to 6.60 ± 1.21% in the age group of 70-79 years, and to 12.3 ± 4.11% in the age group of 80+ years. In multivariate analysis, PEX prevalence was associated with higher age (P<0.001; regression coefficient B:0.11; odds ratio (OR): 1.11 (95%CI: 1.09, 1.13)), lower body mass index (P = 0.001; B: -0.12; OR: 0.88 (95CI: 0.82, 0.95)) and higher diastolic blood pressure (P = 0.002; B: 0.02; OR: 1.03 (95%CI: 1.01, 1.04)). In the multivariate analysis, PEX was not associated with retinal nerve fiber layer cross section area (P = 0.76) and presence of open-angle glaucoma (P = 0.15). CONCLUSIONS: In a rural Central Indian population aged 30+ years, PEX prevalence (mean: 1.49 ± 0.18%) was significantly associated with older age, lower body mass index and higher diastolic blood pressure. It was not significantly associated with optic nerve head measurements, refractive error, any ocular biometric parameter, nuclear cataract, early age-related macular degeneration and retinal vein occlusion, diabetes mellitus, smoking, and dyslipidemia.

Prevalence of optic disc hemorrhages in rural central India. The Central Indian Eye and Medical Study.

PURPOSE: To determine the frequency of optic disc hemorrhages in a rural Indian population. METHODS: The population-based Central Indian Eye and Medical Study included 4711 subjects. Mean age was 48.5±12.9 years (range: 30-100 years). Color optic disc photographs were examined. RESULTS: Optic disc photographs were available for 4570 (97.0%) subjects. Prevalence of disc hemorrhages was 17/8869 (0.19%; 95%CI:0.10,0.28) per eye and 16/4570 (0.35±0.09%; 95%CI:0.18,0.52) per subject. Prevalence of disc hemorrhages increased from 0.05% (95%CI:0.00,0.13) in the age group of 30-39 years to 0.25% (95CI:0.00,0.49) in the age group of 60-69 years and to 0.91% (95%CI:0.24,1.58) in the age group of 70+ years. After adjusting for older age, higher systolic blood pressure, diabetes mellitus, myopic refractive error, smaller neuroretinal rim area and thinner retinal nerve fiber layer, occurrence of disc hemorrhages was associated only with glaucomatous optic nerve damage (P<0.001; Odds ratio: 87; 95%CI:32,239). Eleven of the 17 (65%; 95%CI:39,90) disc hemorrhages were found in glaucomatous eyes. Out of 193 glaucomatous eyes, 11 eyes (5.7%; 95%CI:2.4,9.0) showed a disc hemorrhage. Out of the 8676 non-glaucomatous eyes, 6 eyes (0.07%; 95%CI:0.01,0.12) had an optic disc hemorrhage. CONCLUSIONS: Prevalence of disc hemorrhages (0.2% per eye; 0.4% per subject) in Indians aged 30+ years was strongly associated with glaucoma after adjustment for age, blood pressure and diabetes mellitus. A disc hemorrhage suggested glaucomatous optic nerve damage with a positive predictive value of 65%. About 6% of glaucomatous eyes showed a disc hemorrhage at the time of clinical examination highlighting the importance of optic disc hemorrhages for the diagnosis of glaucoma.

Prevalence and associated factors of glaucoma in rural central India. The Central India Eye and Medical Study.

PURPOSE: To assess the prevalence of glaucoma in rural Central India. METHODS: The population-based Central India Eye and Medical Study is a population-based study performed in a rural region of Central India. The study included 4711 subjects (aged 30+ years). A detailed ophthalmic and medical examination was performed. Glaucoma was defined by glaucomatous optic disc morphology, and in a second step, by the criteria of the International Society of Geographical and Epidemiological Ophthalmology (ISGEO). RESULTS: Optic disc photographs were available for 4570 (97.0%) subjects. Glaucoma was detected in 122 subjects (51 unilateral) (2.67% (95%CI: 2.20, 3.14). Glaucoma prevalence for the age groups of 30-39yrs, 40-49yrs, 50-59yrs, 60-69yrs, 70-79yrs, and 80+ years was 0.54% (95%CI: 0.11, 0.98), 1.03% (95%CI: 0.49, 1.57), 1.40% (95%CI: 0.58, 2.23), 6.62% (95%CI: 4.92, 8.31), 8.71% (95%CI: 5.55, 11.75), and 14.3% (95%CI: 4.13, 24.4), respectively. In multivariable analysis, glaucoma was associated with higher age (P<0.001), lower body mass index (P = 0.025), lower blood hemoglobin concentration (P = 0.03), higher intraocular pressure (P<0.001), disc hemorrhages (P<0.001), higher prevalence of myopic retinopathy (P<0.001), lower level of education (P = 0.03), longer axial length (P<0.001), thinner retinal nerve fiber layer (P<0.001), higher vertical cup/disc diameter ratio (P<0.001), and narrow anterior chamber angle (P = 0.02). Ratio of open-angle glaucoma to angle-closure glaucoma was 7.7:1 (1.93% (95%CI: 1.64, 2.22) to 0.24% (95%CI: 0.14, 0.34)). Using the ISGEO criteria, glaucoma prevalence was 2.8% (95%CI: 2.3, 3.3) with a less clear association with older age. CONCLUSIONS: Glaucoma prevalence in remote rural Central India is comparable to other regions. Associated factors were older age, lower body mass index, lower blood concentration of hemoglobin, lower level of education, higher intraocular pressure, disc hemorrhage, myopic retinopathy, and longer axial length. The ratio of open-angle glaucoma to angle-closure glaucoma was about 8:1.

Intraocular pressure and associated factors: the central India eye and medical study.

PURPOSE: To determine the range of intraocular pressure (IOP) in a rural Central Indian population and to evaluate existing and identify potential new ocular, medical, and socioeconomic factors associated with IOP. METHODS: This is a population-based study carried out in Nagpur in Central India. A single IOP measurement was taken using Goldmann applanation tonometry and population IOP was described using standard descriptive statistics. RESULTS: Of 5885 eligible patients, 9338 eyes of 4686 patients were included in the study. The mean IOP was 13.6±3.4 mm Hg (median: 14 mm Hg; range: 2 to 56 mm Hg). In multivariate regression analysis, the following factors, with correlation coefficients (r) and P values reported in parenthesis, were found to be associated with IOP. Ocular factors included higher corneal power (0.12; P=0.004), lower central corneal thickness (0.02; P<0.001), and higher myopic refractive power (-0.13; P=0.001). Medical factors included diastolic blood pressure (0.05; P<0.001), pulse rate (0.02; P=0.005), and body mass index (0.05; P=0.01). Socioeconomic factors included level of education (0.15; P=0.05) and livestock ownership (-0.18; P=0.008). CONCLUSION: Low mean IOP was found when compared with other epidemiologic studies and this may be explained by the low central corneal thickness found in the study population. Several known ocular and medical factors and new socioeconomic factors were found to be associated with IOP. Identifying risk factors associated with IOP in different populations may allow clinicians to better define and recognize subgroups of patients at risk of elevated IOP. Newly identified socioeconomic-IOP associations will need to be validated in future studies.

Prevalence of age-related macular degeneration in rural central India: the Central India Eye and Medical Study.

PURPOSE: To evaluate the prevalence of age-related macular degeneration (AMD) in the adult population of rural central India. METHODS: The population-based Central India Eye and Medical Study was conducted in rural central India and included 4,711 subjects (aged ≥30 years). Age-related macular degeneration was defined by the international classification of the Wisconsin age-related maculopathy grading system. RESULTS: Fundus photographs were available for 4,542 subjects (96.4%). In subjects aged ≥40, ≥50, and ≥60 years, prevalence of early AMD was 6.1 ± 0.4% (95% confidence interval [CI]: 5.3-6.9%), 8.2 ± 0.6% (95% CI: 7.0-9.4%), and 8.3 ± 0.8% (95% CI: 6.8-9.9%), respectively, and that of late AMD was 0.2 ± 0.8% (95% CI: 0.1-0.4%), 0.2 ± 0.1% (95% CI: 0.1-0.4%), and 0.6 ± 0.2% (95% CI: 0.2-1.0%), respectively. The prevalence of early AMD increased from 1.3 ± 0.3% per subject in the 30-year-old to 40-year-old group, to 3.6 ± 0.5% in the 41-year-old to 50-year-old group, to 7.9 ± 0.9% in the 51-year-old to 60-year-old group, to 10.0 ± 1.1% in the 61-year-old to 70-year-old group, to 8.3 ± 0.2% in the 71-year-old to 80-year-old group, and to 8.0 ± 5.5% in the ≥81-year-old group. Age-related macular degeneration was causative for visual impairment (best-corrected visual acuity in the better eye: <20/60 and ≥20/400) in 3 of 342 subjects (0.9%) and for blindness (visual acuity <20/400) in 0 of 17 subjects. CONCLUSION: After age adjustment, AMD was found less frequently in the adult population of rural central India than in European populations. Accordingly, visual impairment because of AMD was relatively uncommon in rural central India.

Body height and ocular dimensions in the adult population in rural Central India. The Central India Eye and Medical Study.

BACKGROUND: To investigate associations between anthropomorphic parameters and ocular dimensions in a typical rural society untouched by the effects of urbanization. METHODS: The Central India Eye and Medical Study performed in rural Central India included 4,711 participants aged 30 or more years. The participants underwent a detailed ophthalmic and medical examination. RESULTS: After controlling for age, gender, level of education, and body mass index (BMI), taller subjects were more likely to have larger eyes with a longer axial length (+0.23 mm for each 10 cm increase in height), lower corneal refractive power (-0.50 diopters for each 10 cm increase in height), deeper anterior chambers (+0.03 mm for each 10 cm increase in height), and longer vitreous cavity (+0.20 mm for each 10 cm increase in height). Central corneal thickness (P = 0.97) and lens thickness (P = 0.08) were not significantly associated with body height. After controlling for age, gender, level of education and height, subjects with a higher BMI had shorter globes (-0.02 mm for each unit increase in BMI), flatter corneas (-0.03 diopters for each unit increase in BMI) and thicker corneas (+0.49 µm for each unit increase in BMI), thicker lenses and longer vitreous cavities. Body height as compared with the BMI had a stronger influence on the ocular biometric data. After correcting for age, gender, level of education and axial length, for each increase in body height by 10 cm or for each increase in BMI by one unit, the refractive error significantly increased by 0.23 diopters (P < 0.001) and by 0.40 diopters (P < 0.001) respectively. CONCLUSIONS: In the rural population of Central India without urbanization-associated myopization, body height and size of the eye were associated with each other: taller subjects had larger eyes with a flatter cornea. An increase in body height per 10 cm was associated with an increase in anterior chamber depth by 1% and an increase in vitreous cavity length by 1%. Subjects with a higher body mass index had shorter eyes, flatter and thicker corneas, and thicker lenses. Taller subjects and subjects with a higher BMI were more hyperopic. Since the occurrence of some ocular diseases depends on eye size and refractive error, the results may be helpful for screening examinations and for elucidating pathogenic associations.

Ocular axial length and its associations in an adult population of central rural India: the Central India Eye and Medical Study.

PURPOSE: To investigate the normal distribution of axial length of the globe, which is a major measurement of the eye, and its associations with other ocular and systemic parameters. DESIGN: Population-based study. PARTICIPANTS: The Central India Eye and Medical Study is a population-based study performed in a rural region of central India. The study comprised 4711 subjects (aged 30+ years) of 5885 eligible individuals (response rate, 80.1%). METHODS: A detailed ophthalmic and medical examination was performed. The axial length was measured sonographically. MAIN OUTCOME MEASURES: Axial length. RESULTS: Axial length measurements were available on 4698 study participants (99.7%). Their mean age was 49.4+/-13.4 years (range, 30-100 years), and the mean refractive error was -0.18+/-1.48 diopters (range, -20.0 to +7.25 diopters). Mean axial length was 22.6+/-0.91 mm (range, 18.22-34.20 mm). In multivariate analysis, axial length was significantly (P<0.001) associated with the systemic parameters of increased age, taller body height, greater body mass index, and higher level of education, and with the ocular parameters of lower best-corrected visual acuity, lower corneal refractive power, deeper anterior chamber, thicker lens, and more myopic spherical power and cylindrical refractive power. Within the highly myopic group, as defined by an axial length that exceeded 26.5 mm, none of these associations (except for the association between axial length and spherical refractive power) were statistically significant (P>0.15) in univariate or multivariate analysis. CONCLUSIONS: In a rural population of central India, the mean ocular axial length was 22.6+/-0.91 mm, which was shorter than that of other populations. Axial length was associated with the systemic parameters of increased age, taller body height, greater body mass index, and a higher level of education, and with the ocular parameters of lower best-corrected visual acuity, lower corneal refractive power, deeper anterior chamber, thicker lens, and more myopic spherical and cylindrical refractive power. These associations were valid only for those eyes that were not highly myopic, whereas axial length was associated with refractive error only in highly myopic eyes. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Central corneal thickness and its association with ocular and general parameters in Indians: the Central India Eye and Medical Study.

PURPOSE: To evaluate the distribution of central corneal thickness (CCT) and its associations in an adult Indian population. DESIGN: Population-based study. PARTICIPANTS: The Central India Eye and Medical Study is a population-based study performed in a rural region close to Nagpur in Central India; it included 4711 subjects (ages 30+ years) of 5885 eligible subjects (response rate, 80.1%). METHODS: The participants underwent a detailed ophthalmic and medical examination, including 200 standardized questions on socioeconomic background, lifestyle, social relations, and psychiatric depression. This study was focused on CCT as measured by sonography and its associations. Intraocular pressure was measured by applanation tonometry. MAIN OUTCOME MEASURES: Central corneal thickness and intraocular pressure. RESULTS: Central corneal thickness measurement data were available on 9370 (99.4%) eyes. Mean CCT was 514+/-33 microm (median, 517 microm; range, 290-696 microm). By multiple regression analysis, CCT was associated significantly with younger age (P<0.001), male gender (P<0.001), higher body mass index (P = 0.006), lower corneal refractive power (P<0.001), deeper anterior chamber (P = 0.02), thicker lens (P = 0.02), and shorter axial length (P = 0.006). Central corneal thickness was not associated significantly with refractive error (P = 0.54) or cylindrical refractive error (P = 0.20). If eyes with a corneal refractive power of 45 or more diopters were excluded, the relationship between CCT and axial length was no longer statistically significant (P>0.05), whereas all other relationships remained significant. Intraocular pressure readings increased significantly (P<0.001) with both higher CCT and higher corneal refractive power. CONCLUSIONS: Indians from rural Central India have markedly thinner corneas than do Caucasians or Chinese, and, as in other populations, CCT is greater in men. CCT was associated with younger age, higher body mass index, lower corneal refractive power, deeper anterior chamber, thicker lens, and shorter axial length. Intraocular pressure readings were associated with CCT, with high readings in those eyes that had thick corneas or steep corneas. Central corneal thickness and steepness of the anterior corneal surface may thus both have to be taken into account when applanation tonometry is performed. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Prevalence, awareness, control, and associations of arterial hypertension in a rural central India population: the Central India Eye and Medical Study.

BACKGROUND: Because relatively little has been known about the actual prevalence of hypertension in India, particularly for its rural population, we investigated the prevalence of arterial hypertension in a rural Indian population. METHODS: The Central India Eye and Medical Study is a population-based study in a rural Central Indian region. It included 4,711 subjects (ages 30+ years) undergoing an ophthalmic and medical examination. Hypertension was defined as systolic blood pressure > or =140 mm Hg and/or diastolic blood pressure > or =90 mm Hg, and/or self-reported current treatment for hypertension. RESULTS: Arterial hypertension was found in 1,041 (22.1%) subjects. Its prevalence was associated with higher age (P < 0.001), higher body mass index (P < 0.001), body height (P = 0.001), higher blood hemoglobin levels (P < 0.001), and elevated blood urea concentration (P = 0.008). It was not significantly associated with gender, level of education, family income, kind of daily physical activities, type of diet, and serum concentrations of cholesterol and creatinine. Among the hypertensive study participants (n = 1,041), 208 (20.0%) subjects were aware of their disease. A current antihypertensive treatment was reported by 84 subjects of the 1,041 arterial hypertensive subjects (8.1 +/- 0.9%). Out of the treated subjects, 24 (29%) had abnormally high diastolic blood pressure measurements and 44 (52%) participants had abnormally high systolic blood pressure measurements. CONCLUSIONS: In a rural Central Indian population of ages 30+ years, the prevalence of arterial hypertension was 22.1 +/- 0.6% with an awareness rate of 20% and a treatment rate of 8%. The low awareness and treatment rate may demand increasing public health efforts.

Refractive error in central India: the Central India Eye and Medical Study.

OBJECTIVE: To evaluate the refractive error and its associations in the adult population of rural Central India. DESIGN: Population-based study. PARTICIPANTS: The Central India Eye and Medical Study is a population-based study performed in a markedly rural region in Central India. It included 4711 subjects (aged 30 years or older) of 5885 eligible subjects (response rate, 80.1%). METHODS: The participants underwent a detailed ophthalmic and medical examination, including standardized questions on the socioeconomic background, lifestyle, and social relations. This study was focused on the refractive error, the prevalence of hyperopia and myopia, and its factors. MAIN OUTCOME MEASURES: Refractive error. RESULTS: After exclusion of pseudophakic or aphakic eyes, 9076 (96.3%) eyes of 4619 (98.0%) subjects (2472 females) were included into the study. The mean refractive error was -0.20+/-1.51 diopters (D). Myopia of more than -0.50 D, -1.0 D, more than -6.0 D, and more than -8 D occurred in 17.0+/-0.6%, 13.0+/-0.5%, 0.9+/-1.4%, and 0.4+/-0.1% of the subjects, respectively. Hyperopia of more than 0.50 D was detected in 18.0+/-0.6% of the subjects. Refractive error was associated significantly (i.e., became more hyperopic) with lower age (P<0.001), lower best-corrected visual acuity (P<0.001), lower corneal refractive power (P<0.001), and shorter axial length (P<0.001). In multivariate analysis, refractive error was not significantly associated with the level of education (P = 0.56). High myopia (>-8 D) was associated significantly with male gender (P = 0.03) and lower best-corrected visual acuity (P<0.001). Mean anisometropia was 0.41+/-1.02 D. It was associated significantly with age (P<0.001), myopic refractive error (P<0.001), and lower best-corrected visual acuity (P<0.001). The mean astigmatic error was 0.29+/-0.60 D and was associated significantly with higher age (P<0.001), level of education (P = 0.01), lower best-corrected visual acuity (P<0.001), and higher corneal refractive power (P<0.001). CONCLUSIONS: The rural population of Central India has not experienced a myopic shift as described for many urban populations at the Pacific Rim. Correspondingly, the relatively low level of education was not associated with myopia. Urbanization may be a major factor for myopization. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Prevalence and associations of keratoconus in rural maharashtra in central India: the central India eye and medical study.

PURPOSE: To evaluate the prevalence and associated factors of keratoconus in the adult Indian population. DESIGN: Population-based study. METHODS: The Central India Eye and Medical Study is a population-based study performed in a rural region close to Nagpur in Central India. It included 4,711 subjects (aged 30 years and above) out of 5,885 eligible subjects (response rate, 80.1%). The participants underwent a detailed ophthalmic and medical examination. This study was focused on the prevalence of keratoconus, defined as an anterior corneal refractive power exceeding 48 diopters (D). RESULTS: Out of the 4,711 subjects, corneal refractive power measurements were available for 4,667 subjects (99.1%). Keratoconus was detected in 212 eyes (2.3%) of 128 subjects (prevalence rate, 2.3% +/- 0.2%). In multivariate analysis, the presence of keratoconus was significantly associated with lower body height (P < .001), lower level of education (P= .03), higher myopic refractive error (P = .004), and thinner central corneal thickness (P = .006). It was not significantly associated with alcohol consumption (P = .99) or smoking (P = .08) nor with questions relating to the psychiatric status. Defining a keratoconus as corneal refractive power of > or =49 D or of > or =50 D, a keratoconus was detected in 58 eyes (0.6%) and 10 eyes (0.1%), respectively. CONCLUSIONS: Keratoconus defined as corneal refractive power of 48+ D has a prevalence of 2.3% +/- 0.2% among Indians aged 30 years and above and living in the rural region of Central India. The prevalence of keratoconus was associated with lower body height, lower level of education, myopic refractive error, and thinner central cornea.

Optic disc size in a population-based study in central India: the Central India Eye and Medical Study (CIEMS).

PURPOSE: To determine optic disc size and its associations in an adult population in central India. METHODS: The Central India Eye and Medical Study (CIEMS), Part 1 is a population-based, cross-sectional cohort study and included 1000 subjects out of 1314 (76.1%) subjects from a rural area of Maharasthra/India, aged 30+ years, invited to participate. Confocal laser scanning tomographic optic disc images were morphometrically examined. RESULTS: Mean optic disc area (2.25 +/- 0.51 mm2, range 1.12-4.61 mm2) was significantly correlated with myopic refractive error (p < 0.001) and axial length (p < 0.001), whereas gender (p = 0.14), body height (p = 0.44) and best corrected visual acuity (p = 0.59) were not significantly associated in multiple regression analysis. CONCLUSIONS: Mean optic disc area is larger in the central Indian population than in White people. Axial length and myopic refractive error are independent factors that influence optic disc size.