Higher Levels of Serum Ionic Calcium are Associated with Macular Edema in Patients with Diabetic Retinopathy.

BACKGROUND: The aim was to study the association of serum total calcium, ionic calcium, and magnesium with increases in macular thickness parameters and photoreceptor ellipsoid zone (EZ) disruption in diabetic macular edema (DME). METHODS: This study is a tertiary care center based observational cross-sectional study with sixty-six consecutive cases, divided into 3 groups of 22 cases each with no diabetic retinopathy (No DR), non-proliferative diabetic retinopathy (NPDR), and proliferative diabetic retinopathy (PDR) and a control group of 22 healthy controls. Best corrected visual acuity (BCVA) was measured on logMAR scale. Central subfield thickness (CST), cube average thickness (CAT), and EZ disruption were assessed using spectral-domain optical coherence tomography (SD-OCT). Serum total calcium, ionic calcium, and magnesium were measured using standard protocol. Data was analyzed statistically. RESULTS: Significant correlation was found between the increase in CST and the increase in serum total calcium and serum ionic calcium. Increase in CAT was significantly correlated with an increase in serum total calcium, serum ionic calcium, and a decrease in serum magnesium. Grades of EZ disruption and logMAR BCVA were also found to be significantly positively associated with serum total calcium and ionic calcium and negatively with serum magnesium. CONCLUSIONS: Increased levels of serum ionic calcium and decreased levels of serum magnesium are associated with an increase in macular thickness and EZ disruption in DME.

Resistive index of central retinal artery is a bioimaging biomarker for severity of diabetic retinopathy.

BACKGROUND: The present study was undertaken to assess the resistive index (RI) of central retinal artery (CRA) as a bioimaging biomarker for the severity of diabetic retinopathy (DR), for the first time. METHODS: Eighty-one consecutive patients of type 2 diabetes mellitus between the ages of 40 and 70 years were included in a tertiary care center-based cross sectional study. Severity of retinopathy was assessed according to Early Treatment Diabetic Retinopathy Study (ETDRS) classification: diabetes mellitus with no retinopathy (No DR) (n = 26); non-proliferative diabetic retinopathy (NPDR) (n = 29); and proliferative diabetic retinopathy (PDR) (n = 26). Twenty-six healthy controls of similar age were also included. Resistive index of CRA was studied using color Doppler and gray scale sonography. Central subfield thickness (CST), cube average thickness (CAT), retinal photoreceptor ellipsoid zone (EZ) disruption, and retinal nerve fiber layer (RNFL) thickness were evaluated using spectral domain optical coherence tomography. Sensitivity and specificity were assessed by receiver operating characteristic (ROC) curve. RESULTS: Mean RI of CRA for the study groups revealed significant increase with severity of diabetic retinopathy (F = 10.24, P < 0.001). The ROC curve analysis showed diagnostic accuracy of RI of CRA (area under curve = 0.841-0.999; sensitivity = 76-100%, specificity = 95.45-100%, P < 0.001) in discriminating controls and patients. Univariate regression analysis revealed significant association between the study groups and RI of CRA (P < 0.001). RI of CRA correlated positively with CST (r = 0.37), CAT (r = 0.45), EZ disruption (r = 0.43) and negatively with RNFL thickness (r = - 0.35) (P < 0.001). CONCLUSIONS: Resistive index of CRA is a reliable bioimaging biomarker for the severity of DR.

Hyperglycemia potentiates the effect of ionic calcium in photoreceptor ellipsoid zone disruption in diabetic retinopathy.

PURPOSE: To study the association of serum ionic calcium and glycated hemoglobin (HbA1c) with retinal photoreceptor ellipsoid zone (EZ) disruption in diabetic retinopathy (DR). METHODS: This is a tertiary care center-based observational cross-sectional study. Sixty-three consecutive cases, divided into 21 cases each with no diabetic retinopathy, non-proliferative diabetic retinopathy and proliferative diabetic retinopathy were included. Twenty-one healthy controls were also included. Ellipsoid zone disruption was assessed using spectral-domain optical coherence tomography. Serum ionic calcium and HbA1c were measured using standard protocol. Patient data from cases were divided into two groups according to their HbA1c levels: group 1 (HbA1c < 7, n = 26) and group 2 (HbA1c > 7, n = 37). Data were analyzed statistically. RESULTS: Mean ionic calcium levels in group 1 and group 2 were 1.131 ± 0.073 mmol/dL and 1.170 ± 0.070 mmol/dL, respectively. In group 1, 11 out of 26 had EZ disruption (42.3%). Similarly, in group 2, 29 out of 37 had EZ disruption (78.4%). On logistic regression analysis, as compared to group 1, ellipsoid zone disruption was found to be positively associated with serum ionic calcium (p = 0.01) in group 2 cases. CONCLUSION: Increased levels of serum ionic calcium are associated with increased EZ disruption in patients with HbA1c > 7 in DR.

Resistive index of ophthalmic artery correlates with retinal pigment epithelial alterations on spectral domain optical coherence tomography in diabetic retinopathy.

BACKGROUND: Retinal pigment epithelium (RPE) plays a significant role in maintenance of integrity of retinal photoreceptors and choriocapillaries. RPE derives its blood supply through ophthalmic artery (OA) via choriocapillaries. RPE topographic alterations have been observed to be associated with severity of retinopathy. The present study was undertaken to assess the correlation between resistive index (RI) of the OA with RPE topographic alterations on Spectral-Domain optical coherence tomography (SD-OCT), to our knowledge, it is for the first time. METHODS: A tertiary care center based cross-sectional study was undertaken after informed consent. Sample size was calculated using 95% confidence interval. Seventy five consecutive cases of type 2 diabetes mellitus between the ages of 40 and 70 years were included. The cases were divided into three groups according to Early Treatment Diabetic Retinopathy Study classification: diabetes mellitus with no retinopathy (No DR) (n = 24); non-proliferative diabetic retinopathy (n = 27); and proliferative diabetic retinopathy (n = 24). Healthy control subjects of similar age group were included (n = 24). RI in OA was studied using Color Doppler imaging. Grades of RPE topographic alterations and retinal photoreceptor ellipsoid zone (EZ) disruption were studied using SD-OCT. Data was analysed using Chi square (χ2) test, analysis of variance (ANOVA), Pearson correlation analysis and Neuman-Keuls test. RESULTS: LogMAR best corrected visual acuity was found to increase significantly with the severity of DR (F = 105.74, p < 0.001). ANOVA revealed a significant increase in RI of OA (F = 14.23, p < 0.001) with severity of diabetic retinopathy. χ2 test revealed significant increase in grades of RPE alterations (χ2 = 71.83, p < 0.001) and EZ disruption (χ2 = 60.59, p < 0.001) with the severity of diabetic retinopathy. Pearson correlation analyses revealed a significant positive correlation between RI of OA with grades of RPE alterations (r = 0.48, p < 0.001) and also between grades of RPE alterations and EZ disruption (r = 0.82, p < 0.001). CONCLUSIONS: Decrease in ocular blood flow resulting from an increase in RI of OA correlates with severity of DR and grades of topographic alterations in RPE. Integrity of EZ was observed to be dependent on RPE.

Association of contrast sensitivity with LogMAR visual acuity and glycosylated hemoglobin in non-insulin dependent diabetes mellitus.

A tertiary care center-based prospective case-control study was undertaken to evaluate the association of contrast sensitivity with LogMAR visual acuity and glycosylated hemoglobin (HbA1c) in 205 cases of non-insulin dependent diabetes mellitus and 115 controls. LogMAR visual acuity and contrast sensitivity were scored using ETDRS and Pelli-Robson charts, respectively. Bivariate correlation between contrast sensitivity and LogMAR visual acuity showed significant inverse correlation in cases without retinopathy (r = -0.466) and with non-proliferative retinopathy (r = -0.307). In a multivariate model, on applying linear regression analysis, LogMAR visual acuity (p < 0.001) and HbA1c (p = 0.002) had significant association with contrast sensitivity. Significant difference in contrast sensitivity was not observed between cases without diabetic retinopathy and with non-proliferative diabetic retinopathy, implying no association with retinal microvascular changes. Contrast sensitivity dysfunction observed in diabetes mellitus results from changes in retinal function secondary to alteration in carbohydrate metabolism depicted in glycosylated hemoglobin.