Sankara Nethralaya Diabetic Retinopathy Epidemiology Research Articles

Prevalence, risk factors and association with glycemic levels of presbyopia in South Indian population.

Purpose:To determine the prevalence of presbyopia and its association with elevated glycemic levels in subjects ≥40 years of age in the South Indian population of Chennai.Methods:This was a retrospective study. Subjects were included from the Sankara Nethralaya Diabetic Retinopathy Epidemiology And Molecular genetics Study (SN-DREAMS 1). Demographic data, detailed medical and ocular history, comprehensive eye examination, and biochemical investigations were performed. Glycosylated hemoglobin results were categorized as controls (4%–5.6%), prediabetic (5.7%–6.4%), and diabetic (≥6.5%) groups. The given presbyopic correction was divided into two groups as within and outside donders limit. Prevalence rates and mean values were determined and compared among the three glycemic groups. The Student t test, the Chi-square test, and multivariate logistic regression analyses were performed.Results:The overall prevalence of presbyopia from our previously conducted SN-DREAMS 1 population of 1414 patients was 79.77% (95% CI: 0.775–0.818). In total, 1128 participants were included for our current secondary analysis with a mean age of 54.40 years (range: 40–83). The number of subjects within and outside donders limit was 1044 (92.55%) and 84 (7.44%), respectively. In each age group (40–49, 50–59, ≥60) regardless of being within or outside donders limits, an increasing trend in the prevalence of presbyopia was noted based on increasing glycemic levels.Conclusion:Our study demonstrated a high prevalence of presbyopia in the South Indian population of Chennai. Findings show that the prevalence of presbyopia in different age groups increases with worsening diabetes status.

Comparison of various fractal analysis methods for retinal images

Retinal vessels are known to behave like a fractal, waherein a part of a geometrical pattern resembles the whole. Although the box counting method has been used most commonly, currently there exists no "best method" for fractal analysis on retinal vessels. In the present study we compared the different methods of fractal analysis of retinal images. This study included 43 normal retinal images from public databases (STARE & DRIVE) and 40 retinal images (20 normal and 20 diseased) collected from an epidemiological study database (Sankara Nethralaya diabetic retinopathy epidemiology and molecular genetics study; SNDREAMS). In our study we calculated and compared the values of fractal dimensions by Box counting method, Hausdorff Fractal Dimension (HFD), Modified Hausdorff Fractal Dimension (MHFD) and Fourier Fractal Dimension (FFD). The coefficient of variation(CV) was the least with HFD methods in different databases (DRIVE & STARE: −0.088, SNDREAMS Normal retinal images: −0.117, SNDREAMS Diseased retinal images: −0.103). Our study showed that HFD method was the best method to calculate the fractal dimensions of normal and diseased retinal images.

Incidence and Progression of Diabetic Retinopathy in Urban India: Sankara Nethralaya-Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS II), Report 1

ABSTRACTPurpose: To evaluate the 4-year incidence and progression of and risk factors for diabetic retinopathy (DR) in an Indian population.Methods: From a cross-sectional study of 1425 subjects with diabetes, 911 (63.9%) returned for 4-year follow-up. After excluding 21 with ungradable retinal images, data from 890 subjects were analyzed. Participants underwent examinations based on a standard protocol, which included grading of retinal photographs.Results: The incidences of DR, diabetic macular edema (DME), and sight-threatening diabetic retinopathy (STDR) were 9.2%, 2.6%, and 5.0%, respectively. In subjects with DR at baseline, the incidence of DME and STDR had increased (11.5% and 22.7%, respectively). 1-step and 2-step progressions of DR were seen in 30.2% and 12.6% of participants, respectively, and 1-step and 2-step regressions were seen in 12.0% and 1.8%, respectively. Incident DR, DME, and STDR were associated with higher systolic blood pressure (odds ratio, OR, 1.21, 2.11 and 1.72, respectively, for every 10 mmHg increase). Incident DR and DME were associated with increasing duration of diabetes (OR 2.29 and 4.77, respectively, for every 10-year increase) and presence of anemia (OR 1.96 and 10.14, respectively). Incident DR was also associated with higher hemoglobin A1c (OR 1.16 for every 1% increase). Variables associated with 1-step progression were every 10 mg/dL increase in serum total cholesterol (OR 15.65) as a risk factor, and 10 mg/dL increase in serum triglyceride (OR 0.52) as a protective factor.Conclusions: The incidences of STDR and DME were higher in people with pre-existing DR than in those without DR at baseline.

Color vision abnormalities in type II diabetes: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study II report no 2

Purpose:The purpose of this study is to assess color vision abnormalities in a cohort of subjects with type II diabetes and elucidate associated risk factors.Methods:Subjects were recruited from follow-up cohort of Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study I. Six hundred and seventy-three eyes of 343 subjects were included from this population-based study. All subjects underwent detailed ophthalmic evaluation, including the Farnsworth-Munsell 100 hue test.Results:The prevalence of impaired color vision (ICV) was 43% (CI: 39.2–46.7). Risk factors for ICV were higher heart rate (odds ratio [OR]: 1.043, [1.023–1.064]) and a higher intraocular pressure (IOP) (OR: 1.086, [1.012–1.165]). Subjects with clinically significant macular edema (CSME) had three times higher chance of having ICV. C1, C2, and C3 are the commonly found Early Treatment Diabetic Retinopathy Study (ETDRS) patterns. The moment of inertia method showed that the angle did not reveal any specific pattern of color vision defect. Although the major and minor radii were high in those with ICV, we did not observe polarity. Confusion index was high in subjects with ICV, indicating a severe color vision defect.Conclusions:The prevalence of ICV was 43% among subjects with type II diabetes. The most commonly observed patterns were increasing severities of the blue–yellow defect on ETDRS patterns, but no specific pattern was observed at the moment of inertia analysis. The presence of CSME, a higher heart rate, and IOP was significant risk factors for ICV. This functional impairment in color vision could significantly contribute to morbidity among subjects with diabetes.

Contrast sensitivity and its determinants in people with diabetes: SN-DREAMS-II, Report No 6.

PurposeTo assess contrast sensitivity (CS) and to elucidate the factors associated with CS among subjects with type 2 diabetes in a cross-sectional population-based study.Patients and methodsSubjects were recruited from a follow-up cohort, Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular genetics Study (SN-DREAMS II). Of 958 subjects who were followed up in SN-DREAMS II, a subset of 653 subjects was included in the analysis. All subjects underwent a comprehensive eye examination, which included CS assessment using the Pelli-Robson chart. The cross-sectional association between CS and independent variables was assessed using stepwise linear regression analysis. A P-value of <0.05 was considered statistically significant.ResultsThe mean age of the study sample was 58.7±9.41 (44-87) years. Mean CS of the study sample was 1.32±0.20 (range: 0-1.65) log units. CS was negatively and significantly correlated with age, duration of diabetes, hemoglobin level, vibration perception threshold (VPT) value, albuminuria, best corrected visual acuity (BCVA), refractive error, total error score (TEM) of FM 100 hue test, and mean retinal sensitivity. In multiple regression analysis, after adjusting for all the related factors, CS was significantly associated with BCVA (β=-0.575; P<0.001), VPT (β=-0.003; P=0.010), severity of cataract (β=-0.018; P=0.032), diabetic retinopathy (β=-0.016; P=0.019), and age (β=-0.002; P=0.029). These factors explained about 29.3% of the variation in CS.ConclusionAmong the factors evaluated, differences in BCVA were associated with the largest predicted differences in CS. This association of CS with visual acuity highlights the important role of visual assessment in type 2 diabetes.

The eye and the kidney: twin targets in diabetes

Diabetes mellitus is both defined by and is a dreaded condition because of microvascular involvement of the eye and the kidneys. The level of glucose at which retinopathy occurs forms the basis for diagnosing diabetes. Despite non-invasive methods being available for its diagnosis, retinopathy is often underdiagnosed and untreated. Eventually it leads to visual loss often in working-age populations. There appears to be ethnic variation in susceptibility to diabetic retinopathy (DR), with prevalence of DR, sightthreatening DR and macular edema being higher in people from South Asia, Africa, Latin America and indigenous tribal populations [1]. The variations are ascribed to differential susceptibility to known risk factors, as well as differences in lifestyle, access to health care and genetic and epigenetic phenomenon. A number of prevalence studies were reported from different parts of India. In a hospital-based report from Kashmir (n, 500 with diabetes), DR was identified in 27 % (n, 135) [2]. Increasing age was a risk factor, and milder forms accounted for the most cases, suggesting that early screening and treatment is necessary [3]. Prevalence studies from rural India are fewer [4]. In a population-based Central India Eye and Medical Study involving more than 4500 subjects, DR was diagnosed by fundus photography utilizing criteria of Early Treatment of Diabetic Retinopathy Study. DR was identified in 15 subjects (0.33 %) of the entire cohort. In subjects with diabetes, DR was present in 9.6 % [5]. Risk factors were increasing age and higher glucose concentrations. All eyes showed only nonsevere forms of DR. There was no significant association with other conventional risk factors or with ocular parameters. In the SN-DREAMS III report no 2 (Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study III), population-based cross-sectional screening was carried out in a rural population of south India (n, 13,079) [6]. DRwas identified using 45° four-field stereoscopic digital photography, along with 30° seven-field stereo digital pairs in those with DR. Among those with diabetes, DRwas identified in 10.3 %, with greater risk in men, insulin users, those with longer duration of diabetes, systolic hypertension and poor glycemic control [6]. In urban Chennai, the CURES Eye Study I, a populationbased screening for diabetes, was carried out in adults aged 20 years and above (n, 26,001). Among 1382 known subjects with diabetes who agreed to undergo four-field stereo colour photography, and 354 newly diagnosed subjects with diabetes, DR was present in 17.6 % [7]. The prevalence of DR was higher in men and those with proteinuria. Another population-based study in South Kerala assessed the prevalence of diabetes and DR in a community-based screening programme. One hundred and sixty camps were held in five southern districts of Kerala (Project Trinetra) [8]. In a pilot hospital-based screening for DR from western India (n, 168) using ETDRS classification, prevalence of DR was 33.9 %; non-proliferative DR was 25.5 % and proliferative DR 8.33 % [9]. The current issue of the Journal reports on the risk factors for DR in sub-Saharan Africa, prevalence in a rural south Indian population, and on biomarkers for DR and screening methods. * G. R. Sridhar sridharvizag@gmail.com

Retinal sensitivity in subjects with type 2 diabetes mellitus: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS II, Report No. 4)

AimTo evaluate retinal sensitivity (RS) in subjects with diabetes in a population-based study and to elucidate associated risk factors for abnormal RS.MethodsA subset of 357 subjects from Sankara Nethralaya Diabetic...

Incidence, Progression, and Associated Risk Factors of Posterior Vitreous Detachment in Type 2 Diabetes Mellitus: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study (SN-DREAMS II, Report No. 7)

ABSTRACTPurpose: To report the incidence and progression of posterior vitreous detachment (PVD) and factors influencing the same in a cohort of patients with type 2 diabetes in a South Indian population. Methods: A subset of 615 subjects from Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study II were included in this study. All of the subjects underwent detailed ophthalmic evaluation including stereo fundus photography. The status of PVD was assessed using B-scan ultrasonography. A p value of <0.05 was considered statistically significant. Results: The incidence of either incomplete PVD (IPVD) or complete PVD (CPVD) from no PVD at baseline visit was 80.8%. Of them, 32.63% converted to CPVD from IPVD at baseline. High prevalence of emmetropia was observed in subjects with stable No PVD. Risk factors associated with the conversion of CPVD from no PVD and IPVD at baseline were age (OR: 1.04, p = 0.002), myopia (OR: 2.14, p = 0.009), and increase in axial length (OR: 1.35, p = 0.004). Subjects undergoing cataract surgery were at 2.32 times higher risk of converting to CPVD (p = 0.038). Conclusion: Independent risk factors for the progression of PVD were increase in age, myopia, increased axial length, and cataract surgery.

Fixation characteristics among subjects with diabetes: SN-DREAMS II, Report No. 5

ObjectiveTo evaluate fixation and scotoma characteristics among subjects with diabetes in a population-based study. DesignCohort study. ParticipantsA subset of 357 subjects was recruited from follow-up cohort of Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study I. MethodsAll subjects underwent detailed ophthalmic evaluation including microperimetry and spectral domain optical coherence tomography. Fixation parameters such as stability of fixation, fixation location, and presence of scotoma were evaluated. A p value less than 0.05 was considered statistically significant. ResultsThe mean age of the study sample was 56.86 ± 8.63 years. Relatively unstable fixation was observed in 73 and poor central fixation in 25 subjects. Among subjects with poor central fixation, 72% (18 subjects) had relatively unstable fixation. Poor central and relatively unstable fixation were significantly associated with best corrected visual acuity (BCVA; p = 0.002 and p = 0.017, respectively). Prevalence rate of scotoma was 24.4%, which was highly prevalent in females (p = 0.035) and among subjects with reduced BCVA (p < 0.001), reduced contrast sensitivity (p < 0.001), cataract (p < 0.001), impaired retinal sensitivity (p < 0.001), and presence of sight-threatening diabetic retinopathy (STDR; p < 0.001). Presence of scotoma was significantly associated with abnormal foveal contour (p = 0.046) and altered inner retinal layers (p < 0.001). ConclusionsWe report that fixation characteristics are independent of ocular characteristics except for BCVA. Female sex, reduced visual acuity and contrast sensitivity, cataract, and STDR were significantly associated with presence of scotoma.

Impairment of Colour Vision in Diabetes with No Retinopathy: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SNDREAMS- II, Report 3).

PurposeTo assess impairment of colour vision in type 2 diabetics with no diabetic retinopathy and elucidate associated risk factors in a population-based cross-sectional study.MethodsThis is part of Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular-genetics Study (SN-DREAMS II) which was conducted between 2007–2010. FM 100 hue-test was performed in 253 subjects with no clinical evidence of diabetic retinopathy. All subjects underwent detailed ophthalmic evaluation including cataract grading using LOCS III and 45° 4-field stereoscopic fundus photography. Various ocular and systemic risk factors for impairment of colour vision (ICV) were assessed in subjects with diabetes but no retinopathy. P value of < 0.05 was considered statistically significant.ResultsThe mean age of the study sample was 57.08 ± 9.21 (range: 44–86 years). Gender adjusted prevalence of ICV among subjects with diabetes with no retinopathy was 39.5% (CI: 33.5–45.5). The mean total error score in the study sample was 197.77 ± 100 (range: 19–583). The risk factors for ICV in the study were women OR: 1.79 (1.00–3.18), increased resting heart rate OR: 1.04 (1.01–1.07) and increased intraocular pressure OR: 1.12 (1.00–1.24). Significant protective factor was serum high-density lipoprotein OR: 0.96 (0.93–0.99).ConclusionsAcquired ICV is an early indicator of neurodegenerative changes in the retina. ICV found in diabetic subjects without retinopathy may be of non-vascular etiology.

Foveal slope measurements in diabetic retinopathy: Can it predict development of sight-threatening retinopathy? Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS II, Report no 8).

Aim:The aim was to assess the foveal slope configuration in subjects with type 2 diabetes in a population-based study.Materials and Methods:A subset of 668 subjects from Sankara Nethralaya Diabetic Retinopathy (DR) Epidemiology and Molecular Genetics Study II, a population-based study, were included in the current study. All the subjects underwent comprehensive ophthalmic evaluation including spectral domain optical coherence tomography. Foveal thickness was assessed in five central early treatment DR study quadrants from the three-dimensional scan and foveal slope was calculated in all the four quadrants.Results:Subjects with sight-threatening DR (STDR) had significantly shallow foveal slope in inferior quadrant (STDR: 7.33 ± 6.26 vs. controls: 10.31 ± 3.44; P = 0.021) when compared to controls and in superior (STDR: 7.62 ± 5.81 vs. no DR: 9.11 ± 2.82; P = 0.033), inferior (STDR: 7.33 ± 6.26 vs. no DR: 8.81 ± 2.81; P = 0.048), and temporal quadrants (STDR: 6.69 ± 5.70 vs. no DR: 7.97 ± 2.33; P = 0.030) when compared to subjects with no DR. Foveal slope was significantly shallow among the older age groups in subjects with no DR (P < 0.001) and non-STDR (P = 0.027). Average foveal slope in the diabetic subjects was independently and significantly correlated with increase in age (r = −0.241; P < 0.001) and central subfield thickness (r = −0.542; P < 0.001).Conclusion:Changes in foveal slope were seen with increasing age; however, in diabetes these segmental slope changes can be seen in late DR (STDR).

Prevalence and risk factors for diabetic retinopathy in rural India. Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study III (SN-DREAMS III), report no 2

ObjectiveThe study was aimed at estimating the prevalence of type 2 diabetes mellitus and diabetic retinopathy in a rural population of South India.DesignA population-based cross-sectional study.Participants13 079 participants were enumerated.MethodsA...

Prevalence and Risk Factors of Diabetic Retinopathy in Subjects with Suboptimal Glycemic, Blood Pressure and Lipid Control. Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study (SN-DREAMS, Report 33)

Purpose: To assess the rate of achieving optimal metabolic control among subjects with type 2 diabetes, to elucidate the influence of suboptimal control on diabetic retinopathy (DR) and to analyze the risk factors associated with DR in the subjects with suboptimal control.Material and methods: A population-based, cross-sectional study was conducted in south India. The study population consisted of 1414 subjects with type 2 diabetes. Optimal control of glycosylated hemoglobin (HbA1c), blood pressure (BP) and lipids was defined as: optimal HbA1c <7%, suboptimal HbA1c ≥ 7%; optimal BP ≤ 130/80 mm Hg, suboptimal BP >130/80 mm Hg; optimal low-density lipoprotein (LDL-C) <100 mg/dl, suboptimal LDL ≥ 100 mg/dl.Results: Of the subjects, 13.6% achieved combined optimal target levels for all metabolic parameters. When compared to subjects with optimal control, those with suboptimal control of HbA1c (trend P < 0.0001) and systolic blood pressure (SBP, trend P = 0.007) were more likely to have DR. Subjects having a combination of suboptimal glycemic and BP control (P < 0.0001 for SBP, P = 0.004 for diastolic blood pressure (DBP)), and suboptimal glycemic, BP and LDL control (P < 0.0001 for SBP, P = 0.017 for DBP), were more likely to have DR when compared to the subjects having optimal control of respective combinations. The factors associated with DR in the subjects with suboptimal control were younger age (P = 0.014 for BP, P = 0.016 for HbA1c), male gender (P = 0.035 for BP, P = 0.027 for HbA1c, P = 0.043 for LDL), presence of anemia (P = 0.021 for BP, P = 0.036 for HbA1c) and microalbuminuria (P < 0.0001 for both BP and HbA1c).Conclusions: We found high prevalence of suboptimal metabolic control among subjects with type 2 diabetes. Suboptimal glycemic and SBP control, and their combination was the most detrimental for the development of DR.

Prevalence of posterior vitreous detachment in the population with type II diabetes mellitus and its effect on diabetic retinopathy: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study SN-DREAMS report no. 23

To report the prevalence of posterior vitreous detachment (PVD), and predisposing factors to PVD and their effect on diabetic retinopathy. Population-based study. The study included subjects with type II diabetes mellitus enrolled from a cross-sectional study. Participants underwent a biochemical examination, and a comprehensive ocular examination which included stereo fundus photography. Diabetic retinopathy was graded by use of Klein's classification and diabetic maculopathy was graded by use of the Early Treatment Diabetic Retinopathy Study (ETDRS) criteria. The status of the posterior vitreous was assessed by use of B-scan ultrasonography. The prevalence of PVD was 63.3 %. The risk factors for PVD included age, gender, sight-threatening diabetic retinopathy, and axial length. It was observed that incomplete PVD could lead to sight-threatening diabetic retinopathy. We report the prevalence and risk factors of PVD in subjects with diabetes mellitus. Incomplete PVD is a major risk factor for sight-threatening diabetic retinopathy.

Prevalence and risk factors for diabetic microvascular complications in newly diagnosed type II diabetes mellitus. Sankara Nethralaya Diabetic Retinopathy Epidemiology And Molecular Genetic Study (SN-DREAMS, report 27)

PurposeThe aims of this study were to report the prevalence of various microvascular complications and to identify the various clinical and biochemical characteristics related to these complications in subjects with newly diagnosed type II diabetes. MethodsOf the 5999 subjects enumerated, 1414 subjects with diabetes (both known and newly diagnosed) were analyzed for the study. Among the diabetic subjects, 248 (17.5%) were newly diagnosed with diabetes and the remaining had history of diabetes. All subjects underwent a detailed standard evaluation to detect diabetic retinopathy (fundus photography), neuropathy (vibration pressure threshold), and nephropathy (microalbuminuria). ResultsThe prevalence of any form of microvascular complication was 30.2% (95% confidence interval [CI]=24.5–35.9). The prevalence of diabetic retinopathy was 4.8%, and that of diabetic nephropathy and neuropathy was 10.5%. The risk factors for developing any form of microvascular complication were increasing age (odds ratio [OR]=1.07, 95% CI=1.04–1.11, P<.0001), increasing systolic blood pressure (OR=1.03, 95% CI=1.01–1.06, P=.001), and increasing hemoglobin (OR=1.39, 95% CI=1.09–1.79, P=.011). The risk factors for diabetic retinopathy and diabetic nephropathy were increasing systolic blood pressure (OR=1.06 [P=.001] for retinopathy and OR=1.04 [P=.012] for nephropathy) and increasing hemoglobin (OR=2.20 [P=.007] for retinopathy and OR=1.57 [P=.023] for nephropathy). The risk factor for diabetic neuropathy was increasing age (OR=1.12, P<.0001). ConclusionsNearly one third of the newly diagnosed type II diabetes subjects had some form of microvascular complication; nephropathy, and neuropathy being commoner than retinopathy.

Prevalence of Visual Impairment and Associated Risk Factors in Subjects with Type II Diabetes Mellitus: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS, Report 16).

Purpose:To report the prevalence of visual impairment (VI) and the associated risk factors in type II diabetic subjects.Materials and Methods:The study included type II diabetes mellitus subjects who were enrolled from a cross-sectional study. Participants underwent biochemical testing and comprehensive ocular examination including stereo fundus photography. The VI was defined based on the World Health Organization criteria.Results:The prevalence of VI was 4% in the cohort. The risk factors associated with the presence of VI included a female gender, age greater than 60 years, low socio-economic status, hypertension, microalbuminuria, macroalbuminuria, neuropathy, use of insulin and alcohol. Various ocular risk factors are nuclear sclerosis, subjects who have undergone cataract surgery, myopia and sight-threatening diabetic retinopathy (STDR). After adjusting for the factors using stepwise logistic regression analysis, hypertension, use of alcohol, post-cataract surgery and myopia were not risk factors. Stepwise logistic regression analysis indicated that VI was higher among subjects older than 60 years (odds ratio (OR): 4.95 [2.67-9.15]) and those who belonged to a low socio-economic status (OR: 2.91 [1.24-6.85]). The systemic risk factors for VI included microalbuminuria (OR: 2.91 [1.59-5.33]), macroalbuminuria (OR: 4.65 [1.57-13.77]) and presence of neuropathy (OR: 1.97 [1.09-3.59]) among subjects. Subjects with nuclear sclerosis (OR: 36.82 [11.12-112.36]) and presence of STDR (OR: 4.17 [1.54-11.29]) were at a higher risk of VI. Cataract was the most common cause of VI in the cohort.Conclusion:Visual impairment, among type II diabetic subjects (4%), is a major public health problem that needs to be addressed. Cataract is the most common reversible cause of vision impairment in this population.

Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study (SN--DREAMS III): Study design and research methodology

BackgroundTo describe the methodology of the Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study III, an ongoing epidemiological study to estimate the prevalence of Diabetes and Diabetic Retinopathy in rural population of Kanchipuram and Thiravallur districts of Tamil Nadu, India and to elucidate the clinical, anthropometric, biochemical and genetic risk factors associated with diabetic retinopathy in this rural population.MethodsSankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study III will be a mobile van based epidemiological study; 11,760 participants aged ≥ 40 years will be recruited from the study areas. Eligible subjects will undergo blood sugar estimation to diagnose Diabetes. Oral Glucose Tolerance Test will be done to conform diabetes. All subjects with diabetes will undergo complete information of knowledge, aptitude and practice of diabetes and diabetic retinopathy, Diet questionnaire, demographic data, socioeconomic status, physical activity, anthropometric measurements, and risk of sleep apnoea. A detailed medical and ocular history, a comprehensive eye examination including refraction, slit lamp biomicroscopy examination, indirect ophthalmoscopy, slit lamp biomicroscopy, digital stereo fundus photography and ultrasound of eye will be done in the mobile van. Blood will be collected for biochemical investigations including blood hemoglobin, glycosylated hemoglobin, lipid profile, urea and creatinine, genetic study. Urine will be collected for microalbuminuria. All fundus photographs will be graded at base hospital. Participants who need treatment will be sent to the base hospital. A computerized database is created for the records.ConclusionThe study is expected to provide an estimate of the prevalence of Diabetes and Diabetic Retinopathy and also a better understanding of the genetic, anthropometric and socio-economic risk factors associated with Diabetic Retinopathy in a Rural South Indian population.

Abnormal sleep patterns in subjects with type II diabetes mellitus and its effect on diabetic microangiopathies: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study (SN-DREAMS, report 20)

To study the prevalence of Abnormal Sleep Patterns (ASPs), gender-wise, in subjects with type II diabetes mellitus and its influence on diabetic microangiopathies. A population-based cross-sectional survey was conducted among 1,414 patients having type II diabetes mellitus. Diabetic retinopathy was graded using stereoscopic digital fundus photography. Neuropathy was assessed by measuring vibration perception threshold using a sensitometer. Nephropathy was diagnosed by the presence of microalbuminuria in the first morning urine sample. ASPs were defined as either short (less than 5 h) or long (more than 9 h) duration of sleep with excessive daytime sleepiness. The Epworth Sleepiness Scale (ESS) score was assessed to note excessive daytime sleepiness; a score of more than 10 was considered as abnormal. The prevalence of ASPs was more in subjects with diabetes than with those without diabetes (14.8 vs. 6.6%) (P = 0.009), especially in women (15.7 vs. 5.6%) (P = 0.021). Likewise, the prevalence of short duration of sleep was higher in subjects with diabetes compared to those without diabetes (6.6 vs. 2.2%) (P = 0.040). The mean age of women subjects with diabetes, having ASPs, was higher than those without diabetes (56.4 ± 8.9 years vs. 47.2 ± 5.9 years, P = 0.033). Women subjects with ASPs had a higher risk of diabetic neuropathy on both univariate and multivariate analysis. ASPs are not only related to diabetes but can also influence the microvascular complications arising due to diabetes, particularly diabetic neuropathy. Diabetology and sleep medicine specialists need to work together to prevent the negative interactions between these two groups.

Prevalence of Metabolic Syndrome and its influence on microvascular complications in the Indian population with Type 2 Diabetes Mellitus. Sankara Nethralaya Diabetic Retinopathy Epidemiology And Molecular Genetic Study (SN-DREAMS, report 14)

BackgroundThe Metabolic syndrome (MS) consists of central obesity, glucose intolerance, hyperinsulinemia, low high density lipoproteins, high triglycerides and hypertension. Different studies have observed that MS causes microvascular complications in patients with type 2 diabetes. The aim of the study was to find out the prevalence of MS in the Indian population with type 2 diabetes mellitus in relation to gender, duration of diabetes, and to evaluate the influence of MS and its individual components on microvascular complications such as diabetic retinopathy, diabetic nephropathy and diabetic neuropathy.MethodsA population-based cross sectional survey was conducted with 1414 patients having type 2 diabetes mellitus. The International Diabetes Federation (IDF) criteria were used to identify the metabolic syndrome. Diabetic retinopathy was graded using the stereoscopic digital fundus photography. Neuropathy was assessed by measuring the vibration perception threshold through a sensitometer. Nephropathy was diagnosed by the presence of microalbuminuria in the first morning urine sample.ResultsThe age and gender adjusted prevalence of MS, using the IDF criteria, in the South Indian population was 73.3%. The prevalence was higher in women (83.3%), compared to men (65.3%). In subjects with diabetes mellitus, without and with MS, the prevalence of retinopathy was 21.3% and 16.9% (p = 0.057); prevalence of nephropathy was 20.5% and 18.0% (p = 0.296), and prevalence of neuropathy was17.2% and 19.4% (p = 0.353) respectively. Overall and in women, the clustering of MS components led to an increase in the prevalence of diabetic nephropathy. The prevalence of retinopathy and neuropathy in MS subjects, who had diabetes for < 10 years, was more in both men and women; it was more in women but not in men when the duration of diabetes varied from 11-20 years.ConclusionsThe association of MS with microangiopathies decreased with an increase in the duration of diabetes. MS behaved differently in men and women. It may need to be managed differently in the two groups.

Estimating the Rate of Non-Participation and Its Influence on the Study Results: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study Report 32

Purpose: To report the non-participation rates in a cross-sectional study, compare participants with non-participants, elucidate barriers for non-response and evaluate the influence of non-responders on the outcome measure. Methods: The Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study had 2 steps in which non- participation was possible. Step 1 was an estimation of fasting blood sugar at the participants’ homes, and step 2 a base hospital examination. The sociodemographic information was collected at the time of enumeration. The barriers against participation were noted at refusal. The data of the participants were compared with the urban Tamil Nadu population data from the 2001 census. Results: The non-participation rate was 3.6% in the field (step 1), and 13.9% at the base hospital (step 2). At step 1, older men and unemployed women had a lesser odds ratio for non-participation than younger age groups. At step 2, employment was significant for non-participation in men, and age between 50 and 59 years, illiteracy and unemployment in women. Conclusion: The barriers against participation differed between steps 1 and 2. The study participants were similar to the population of urban Tamil Nadu. Hence, the results of the study can be generalized to the urban Indian population.