Background: Diabetic retinopathy (DR) is indicated as a major cause of blindness in the world. Emerging evidence supports the interaction of iron metabolism with diabetes. However, little research is available concerning the relationship between iron metabolism and DR. The intent of this paper is to describe the correlation between serum iron and the occurrence of DR. Methods: A total of 5321 participants who underwent related examinations as part of the National Health and Nutrition Examination Survey (2005–2008) were included. DR was defined by the criteria of the Early Treatment for Diabetic Retinopathy Study based on nonmydriatic fundus photography. The cutoff point of serum iron for DR was explored by the receiver operating characteristics curve. The relationship of serum iron with the occurrence of DR was explored by multivariate logistic regression models. Results: Participants with DR had significantly lower serum iron than the control group. Serum iron was negatively correlated with the occurrence of DR after the adjustment of pertinent variables (an odds ratio (OR) of 0.995 (95% CI: 0.992–0.999)). After dividing serum iron into quartiles, the third quartile was associated with DR with an OR of 0.601 (95% CI: 0.418–0.863). Furthermore, the cutoff point of serum iron had an inverse relationship for the occurrence of DR with an OR of 0.766 (95% CI: 0.597–0.984). Conclusion: Serum iron has an inverse association with the occurrence of DR in diabetic adults. The assessment of serum iron levels might be a part of follow-up visits with diabetic patients.

It has rarely been studied whether the presence and severity of diabetic retinopathy (DR) could influence the renal disease progression among all chronic kidney disease (CKD) diabetic patients. This study investigates the characteristics of diabetic patients, with different stages of chronic kidney disease (CKD), according to the occurrence of diabetic retinopathy and determines the influence of retinopathy in the deterioration of renal function. We conduct a multicenter, longitudinal cohort study based on the Epidemiology and Risk Factors Surveillance of the CKD project (2008–2013) and the National Health Insurance Research Database (NHIRD) (2001–2013). A total of 4050 diabetic patients with CKD, 20–85 years of age, from 14 hospitals and the community are included in this study. As compared to CKD patients without DR, CKD patients with DR have a lower baseline estimated glomerular filtration rate (eGFR) (39.17 ± 30.36 mL/min per 1.73 m² vs. 54.38 ± 33.67 mL/min per 1.73 m² ); poorer glycemic control (higher glycated hemoglobin (HbA1c) 7.85 ± 4.97 vs. 7.29 ± 4.02, p < 0.01); higher proteinuria (urine protein-to-creatinine ratio (UPCR )1.94 ± 2.96 g/dL vs. 0.91 ± 2.11 g/dL, p < 0.01); more anemia (Hb 11.22 ± 2.43 g/dL vs. 12.39 ± 3.85 g/dL, p < 0.01), and more hypoalbuminemia (3.88 ± 0.95 g/dL vs. 4.16 ± 1.74 g/dL, p < 0.01). Later stage (stage 3b–5) CKD patients with DR had significantly higher CKD progression compared with patients without DR (OR (odds ratio) 1.66 (1.36–2.02)). Patients with proliferative DR had significantly higher CKD progression events compared to patients with non-proliferative DR (OR 2.18 (1.71–2.78)). The presence and severity of DR is a risk factor for CKD progression among our Taiwanese CKD patients with diabetes. Prevention and early detection of DR are important and DR should be routinely screened as early as possible among diabetic CKD patients.

Age-related macular degeneration (AMD) is a vision-threatening age-associated disease. The retinal pigment epithelial (RPE) cells phagocytose and digest photoreceptor outer segment (POS). Incomplete digestion of POS leads to lipofuscin accumulation, which contributes to the pathology of the AMD. Autophagy could help reduce the amount of lipofuscin accumulation. In the present study, we evaluated the effects of glucosamine (GlcN), a natural supplement, on the induction of autophagy and POS-derived lipofuscin-like autofluorescence (LLAF) in ARPE-19 cells in vitro, and investigated the potential molecular pathway involved. Our results revealed that GlcN had no effect on phagocytosis of POS at the lower doses. GlcN treatment induced autophagy in cells. GlcN decreased the LLAF in native POS-treated cells, whereas malondialdehyde or 4-hydroxynonenal-modified POS attenuated this effect. 3-Methyladenine inhibited GlcN-induced autophagy and attenuated the effect of GlcN on the decrease of the native POS-derived LLAF. Furthermore, GlcN induced the phosphorylation of AMP-activated protein kinase (AMPK) and inhibited the phosphorylation of mammalian target of rapamycin (mTOR), whereas Compound C inhibited these effects of GlcN. Altogether, these results suggest that GlcN decreased the native POS-derived LLAF through induction of autophagy, at least in part, by the AMPK–mTOR pathway. This mechanism has potential for the preventive treatment of lipofuscin-related retinal degeneration such as AMD.

Purpose: A prospective study was performed to evaluate refractive and ocular biometric changes in acute hyperglycemic status in patients with diabetes mellitus. Methods: From January to August 2002, 48 eyes of 24 patients with persistent diabetes and a plasma glucose level 17 mmol/L or HbA1c 10.0% on admission were enrolled in this prospective study. Upon admission to Tri-Service General Hospital in Taipei, Taiwan, these patients underwent intensive glycemic control. The basic ophthalmic examinations, including visual acuity, intraocular pressure measurement, slit lamp, and fundus examinations, were conducted. The ocular parameters including refraction, anterior chamber depth, lens thickness, axial length, mean keratometry and thinnest corneal thickness were evaluated by A-mode scan and Orbscan II. Each patient underwent clinical follow-up visits at 1, 2, and 4 weeks after the acute hyperglycemic episode. Results: Of the 24 patients, 18 were male and 6 were female. The mean age of the patients was 55 years (range: 38 to 69). Comparing the refractive status on admission and at week 4, the authors found that 8 cases (16 eyes, 33%) showed hyperopia during hyperglycemia (+1.9±0.8 D), but in the other 16 cases (32 eyes, 67%), there were no significant changes. In addition, there were also no significant changes in anterior chamber depth, lens thickness, axial length, thinnest corneal thickness, or mean keratometry in the follow-up period. Conclusions: Transitory hyperglycemia produces hyperopia. The alteration in refractive index in the lens may contribute to the hyperopic change, but no change of ocular biometrics in lens or cornea is observed.

Purpose: The aim of this study was to develop a non-cytotoxic, biocompatible innovative acellular porcine cornea (APC) for corneal wound healing and corneal blindness treatment. Methods: APC was produced by using supercritical carbon dioxide (SCCO₂) to decellularize the porcine cornea. Decellularization of the porcine cornea was examined by hematoxylin and eosin staining and 4,6-diamidino-2-phenylindole, dihydrochloride staining. The residual DNA content of APC was analyzed in comparison with the native porcine cornea. Virus inactivation up to at least 6 log₁₀ was confirmed for the stepwise process of APC for 4 different model viruses. In addition, a series of in vitro and in vivo tests in accordance with ISO-10993 biocompatibility assay and animal performance tests were performed. Results: APC produced by the SCCO₂ process revealed complete decellularization, without any residual non-collagenous proteins. The scanning electron microscopy structural features of the decellularized cornea were similar to those of human. APC was found to be nontoxic and exhibited excellent biocompatibility in both in vitro and in vivo studies. The animal performance test proved that APC exerted excellent adaptability on the cornea and no sign of irritation and good compatibility in lamellar corneal transplantation. Conclusions: APC manufactured by SCCO₂ technology revealed complete cells and non-collagenous protein removal compared with the Triton–sodium dodecyl sulfate decellularization process. APC showed excellent biocompatibility in rabbit lamellar corneal transplantation with a follow-up to 1 year. APC can be a potential substitute for human-donated cornea for corneal transplantation in the near future.