Evaluation of corneal endothelium in children and adolescents with type 1 diabetes mellitus

Particularities of Cataract Surgery in Elderly Patients: Corneal Structure and Endothelial Morphological Changes after Phacoemulsification

The aim of this study was to evaluate the influence of ultrasounds used in phacoemulsification during cataract surgery on the corneal structure and morphology in patients over 65 years. We compared the outcomes of phacoemulsification techniques in terms of corneal cell morphology in 77 patients over 65 years old and 43 patients under 65 years old. Corneal cell density, central corneal thickness and hexagonality were measured preoperatively and post-surgery (at 1 and 4 weeks) by specular microscopy. The effect of gender, axial length and anterior chamber depth on the parameters of corneal endothelium were evaluated. In both groups, a progressive decrease in endothelial cells was observed, starting from the first week post-surgery until the fourth postoperative week. The central corneal thickness increased in both groups with maximum values at the first week postoperatively, while their initial values were restored in the fourth week post-surgery, with no statistical difference between groups. Statistically significant differences were noticed in terms of cell hexagonality in the group over 65, showing smaller hexagonality at all preoperative and postoperative time points compared to group under 65. Our result highlights the importance of routine specular microscopy performed before surgery, regardless the age of the patients, with caution and careful attention to the phaco power intensity, ultrasound energy consumption and intraoperative manipulation of instruments, as well as proper use of viscoelastic substances to reduce corneal endothelium damage, especially in elderly patients.

Corneal parameters in diabetics versus non-diabetics and correlation with various blood sugar parameters

Aim: To compare corneal parameters in diabetics versus age-group-matched non-diabetics; also, to correlate these parameters with the duration of diabetes, glycated haemoglobin (HbA1c) levels, and severity levels of diabetic retinopathy (DR). Materials and methods: A comparative study was conducted at a tertiary eye-care center from January 2020 to December 2020. Two-hundred patients (400 eyes) with type-2 diabetes (100) and age-sex-matched non-diabetics (100) were included. Corneal morphological parameters like central corneal thickness (CCT), endothelial cell density (ECD), coefficient of variance (CoV), hexagonality (6A), and average cell area were recorded by specular microscopy. These parameters were correlated with the duration of diabetes, severity of disease based upon fasting blood glucose levels, HbA1c, and grade of DR. Mean and standard deviation were calculated, and regular distribution of continuous data was tested using independent sample t-test and ANOVA. Results: Mean ECD (2447.32 ± 269.89/mm2), 6A (45.03 ± 6.71%), and IOP (15.47 ± 2.02 mmHg) changed in diabetic cases and were significantly low in diabetics, whereas, mean average cell area (413 ± 50.19 mm2), standard deviation (167.05 ± 77.91), CCT (525.81 ± 36.69) and CoV (39.84 ± 15.59%), were significantly high in diabetics. Mean CCT had insignificant variation. Subgroup analysis within diabetics showed a statistically significant reduction of ECD, cell count, and 6A with increased duration of diabetes, poor glycaemic control, and raised HbA1c. Discussion: The corneal endothelial analysis is vital in daily clinical practice and provides valuable evidence concerning the viability of corneal endothelium in various intraocular surgeries. Uncontrolled DM harms the cornea with 70% of diabetics resulting in complications like keratopathy. The study highlighted that the increased duration of diabetes raised HbA1c, and poor glycemic control negatively affected corneal morphology. Our study showed a definite reduction in ECD and 6A in diabetics compared to non-diabetics. Conclusion: A definite reduction in the corneal endothelial counts, cell density, and hexagonality was found in type-2 diabetics compared to non-diabetics. Abbreviations: DM = Diabetes Mellitus, CCT = central corneal thickness, ECC = endothelial cell counts, ECD = endothelial cell density, CoV = coefficient of variance, 6A = hexagonality, DR = Diabetic retinopathy, SD = Standard of deviation, IOP = Intraocular pressure.

Rat Model of Type 2 Diabetes Mellitus Recapitulates Human Disease in the Anterior Segment of the Eye

Changes in the anterior segment of the eye due to type 2 diabetes mellitus (T2DM) are not well-characterized, in part due to the lack of a reliable animal model. This study evaluates changes in the anterior segment, including crystalline lens health, corneal endothelial cell density, aqueous humor metabolites, and ciliary body vasculature, in a rat model of T2DM compared with human eyes. Male Sprague-Dawley rats were fed a high-fat diet (45% fat) or normal diet, and rats fed the high-fat diet were injected with streptozotocin i.p. to generate a model of T2DM. Cataract formation and corneal endothelial cell density were assessed using microscopic analysis. Diabetes-related rat aqueous humor alterations were assessed using metabolomics screening. Transmission electron microscopy was used to assess qualitative ultrastructural changes ciliary process microvessels at the site of aqueous formation in the eyes of diabetic rats and humans. Eyes from the diabetic rats demonstrated cataracts, lower corneal endothelial cell densities, altered aqueous metabolites, and ciliary body ultrastructural changes, including vascular endothelial cell activation, pericyte degeneration, perivascular edema, and basement membrane reduplication. These findings recapitulated diabetic changes in human eyes. These results support the use of this model for studying ocular manifestations of T2DM and support a hypothesis postulating blood-aqueous barrier breakdown and vascular leakage at the ciliary body as a mechanism for diabetic anterior segment pathology.

Central Corneal Thickness and Intraocular Pressure in Children with Type 1 Diabetes Mellitus

PURPOSE

The aim of this study is to determine the mean central corneal thickness (CCT) and mean intraocular pressure (IOP) in children with type 1 diabetes mellitus (T1DM) and to determine the relationship between CCT and IOP on the one hand and age, sex, retinopathy hemoglobin A1c (HbA1c), and duration of diabetes on the other.

METHODS

This is a case-control, hospital-based study conducted at Hospital Universiti Sains Malaysia between January and November 2022. Thirty-eight children with T1DM were recruited as cases, and 38 healthy children were recruited as controls. The cases and controls then underwent ophthalmic examination, IOP measurement, and CCT measurement using optical coherence tomography (OCT) of the right eye. The IOP measurements were adjusted for CCT for further analysis.

RESULTS

The means of CCT and IOP values were significantly higher in the T1DM group than in the control group (all p = 0.02). The mean CCT was 542.18 ± 20.40 μm in the T1DM group, and 529.52 ± 26.17 μm in the control group. The mean IOP was 14.68 ± 1.98 mmHg in the T1DM group, and 13.52 ± 1.66 mmHg in the control group. The mean HbA1c was 10.68% ± 2.49% in the T1DM group. Age and duration of DM were found to have a significant association with CCT in children with T1DM. The duration of DM was also found to be significantly associated with the IOP. Sex and HbA1c levels were found to have no significant relationship with either CCT or IOP.

CONCLUSIONS

Children with T1DM have significantly higher CCT and IOP than the average child. The duration of DM is a significant factor that impacts both CCT and IOP. In addition, age is another factor that affects CCT in children with T1DM.

Evaluation of the Corneal Endothelium Following Cataract Surgery in Diabetic and Non-Diabetic Patients

The aim of this study was to evaluate the influence of phacoemulsification cataract surgery on the state of the corneal endothelium in diabetic versus non-diabetic patients. We compared the corneal cell morphology in 48 diabetics with good glycemic control and 72 non-diabetic patients before and after uneventful phacoemulsification. Corneal cell density, central corneal thickness, and hexagonality were measured preoperatively and post-surgery (at 1 and 4 weeks) by specular microscopy. The effect of age, gender, axial length, and anterior chamber depth on the parameters of the corneal endothelium were evaluated. We noticed a drop in the endothelial density in both groups postoperatively: a mean endothelial cell loss of 472.7 ± 369.1 in the diabetic group was recorded versus 165.7 ± 214.6 mean loss in the non-diabetic group after the first week. A significant increase in central corneal thickness was also noticed in both groups one week after phacoemulsification, but no statistical significance after 4 weeks in the diabetic group. In terms of cell hexagonality, statistically significant differences were noticed after 4 weeks in both groups. Overall, a significant difference between diabetic and non-diabetic population was noticed in terms of corneal endothelial cell loss after uneventful phacoemulsification cataract surgery. Routine specular microscopy and HbA1c evaluation is recommended before cataract surgery, while intraoperative precautions and high monitorisation in terms of pacho power intensity and ultrasound energy, along with a proper application of the dispersive viscoelastic substances are essential to reduce the risk of endothelial damage.

Diabetic Retinopathy: Soluble and Imaging Ocular Biomarkers

Diabetic retinopathy (DR), the most common microvascular complication of diabetes mellitus, represents the leading cause of acquired blindness in the working-age population. Due to the potential absence of symptoms in the early stages of the disease, the identification of clinical biomarkers can have a crucial role in the early diagnosis of DR as well as for the detection of prognostic factors. In particular, imaging techniques are fundamental tools for screening, diagnosis, classification, monitoring, treatment planning and prognostic assessment in DR. In this context, the identification of ocular and systemic biomarkers is crucial to facilitate the risk stratification of diabetic patients; moreover, reliable biomarkers could provide prognostic information on disease progression as well as assist in predicting a patient's response to therapy. In this context, this review aimed to provide an updated and comprehensive overview of the soluble and anatomical biomarkers associated with DR.

Corneal endothelial cell morphology and optical coherence tomography findings in children with type 1 diabetes mellitus

Purpose

To evaluate central macular thickness, retinal nerve fibre layer thickness, corneal endothelial cell density and central corneal thickness in children with Type 1 Diabetes Mellitus (DM).

Methods

Thirty children with Type 1 DM and 30 age-matched children as controls were examined. Central macular thickness (CMT) and four quadrants of retinal nerve fibre layer thickness (RNFLT) were measured by optical coherence tomography (OCT), while endothelial cell density (ECD), coefficient of variation in cell size (CV), hexagonality (HEX) and central corneal thickness (CCT) were measured by noncontact specular microscopy.

Results

The mean ECD was 2810.77  ±  273.47 cells/mm2 and the mean hexagonality ratio was 49.77  ±  13.2 both were significantly lower (p < 0.001, p  =  0.037 respectively) in the diabetic group compared to the control group. The mean CV was 37.6  ±  7.27, it was significantly higher (p  =  0.024) in the diabetic group than the control group. The mean corneal thickness was greater in the DM group than the controls, but the difference was not significant (p  =  0.176). There were no significant differences in CMT or RNFLT between the two groups. There was a negative correlation between the HbA1c levels and the thickness of the superior quadrants of RNFL (r  =  -0.406, p  =  0.026). The duration of diabetes had no significant correlations with the corneal and retinal parameters.

Conclusion

The diabetic children had changes in corneal endothelial morphology and there was a negative correlation between HbA1c levels and superior quadrant of RNFLT.

Corneal and lenticular clarity in children with inflammatory disease as assessed by Scheimpflug imaging

BACKGROUND

Corneal and lenticular optical properties are not well-documented in pediatric patients with inflammatory diseases. Here we aimed to evaluate corneal and lenticular optical density as well as corneal morphology in children with ocular and/or systemic inflammation by Scheimpflug imaging.

METHODS

Fifty-five eyes of 29 children with non-infectious uveitis, 56 eyes of 28 children with systemic inflammation without uveitis and 60 eyes of 31 healthy children were included. Corneal/lenticular optical density, corneal volume, central corneal thickness, keratometry were analyzed by Pentacam HR. Corneal endothelial cell density, hexagonal cell ratio and coefficient of variation were measured by specular microscope.

RESULTS

The mean age was 12.0±3.1 years, 11.9±4.0 years and 11.3±3.4 years whereas the female/ratio was 15/14, 15/13 and 14/17 in uveitis, systemic inflammation and control groups respectively. Uveitis type was anterior uveitis in 16 (29.1%) eyes, intermediate uveitis in 32 (58.2%) eyes and panuveitis in 7 (12.7%) eyes. Twenty-two (40%) eyes had active uveitis whereas 33 (60%) eyes had inactive uveitis. Corneal optical density was greater in uveitis group compared with other groups (p=0.001, Kruskal-Wallis test). Lenticular density and corneal parameters other than optical density were not different between the groups (p>0.05). Corneal optical density was higher in active uveitis than inactive uveitis (22/33 eyes, p=0.017).

CONCLUSION

Children with uveitis had decreased corneal clarity compared with systemic inflammation group and healthy controls, while lenticular clarity was similar between the groups. Corneal endothelial parameters did not change significantly based on ocular/systemic inflammation. Scheimpflug imaging provides objective corneal and lenticular optical density measurements.

Mechanistic investigations of diabetic ocular surface diseases

With the global prevalence of diabetes mellitus over recent decades, more patients suffered from various diabetic complications, including diabetic ocular surface diseases that may seriously affect the quality of life and even vision sight. The major diabetic ocular surface diseases include diabetic keratopathy and dry eye. Diabetic keratopathy is characterized with the delayed corneal epithelial wound healing, reduced corneal nerve density, decreased corneal sensation and feeling of burning or dryness. Diabetic dry eye is manifested as the reduction of tear secretion accompanied with the ocular discomfort. The early clinical symptoms include dry eye and corneal nerve degeneration, suggesting the early diagnosis should be focused on the examination of confocal microscopy and dry eye symptoms. The pathogenesis of diabetic keratopathy involves the accumulation of advanced glycation end-products, impaired neurotrophic innervations and limbal stem cell function, and dysregulated growth factor signaling, and inflammation alterations. Diabetic dry eye may be associated with the abnormal mitochondrial metabolism of lacrimal gland caused by the overactivation of sympathetic nervous system. Considering the important roles of the dense innervations in the homeostatic maintenance of cornea and lacrimal gland, further studies on the neuroepithelial and neuroimmune interactions will reveal the predominant pathogenic mechanisms and develop the targeting intervention strategies of diabetic ocular surface complications.

Cataract Surgery Considerations for Diabetic Patients

PURPOSE OF REVIEW

Given the epidemiology and demographic trends of diabetes mellitus and cataracts, ophthalmologists are likely to encounter patients with both comorbidities at an increasing frequency. Patients with diabetes represent a higher risk population than healthy patients for cataract surgery. In this review, we discuss key risks and risk-mitigation practices when performing cataract surgery on these patients.

RECENT FINDINGS

Patients with diabetes continue to represent a high-risk surgical population: Nagar et al. suggest a dose-dependent relationship may exist between number of intravitreal injections and likelihood of posterior capsular rupture. However, novel treatments are improving outcomes for patients with diabetes. Several studies have reported intracameral phenylephrine/ketorolac may reduce the incidence of post-operative cystoid macular edema while others have discussed the efficacy of pre-treatment and post-treatment with intravitreal bevacizumab on improving cataract surgery outcomes in patients with diabetic retinopathy. Pre-operatively, ophthalmologists should perform an enhanced evaluation, consider timing and lens selection decisions, and complete any appropriate pre-operative treatment. Peri-operatively, surgeons should be aware of pupillary dilation adjustments, combination surgery options, and potential complications. Post-operatively, clinicians should address pseudophakic cystoid macular edema, diabetic macular edema, diabetic retinopathy, and posterior capsular opacification.

Diabetes Mellitus Type 1 has a Higher Impact on Corneal Endothelial Cell Density and Pachymetry than Diabetes Mellitus Type 2, Independent of Age: A Meta-Regression Model

PURPOSE

Patients with diabetes mellitus (DM) often have keratopathy. However, the compromise of the corneal endothelium in type 1 DM (T1DM) and type 2 DM (T2DM) has so far not been well characterized.

METHODS

We performed a systematic literature search to find articles on humans combining T1DM and/or T2DM and the corneal endothelium. The period was from inception to June 2020. The meta-regression evaluated the role of each type of DM on corneal endothelial cell density (CED) and pachymetry. The statistical models included age as a modulator to discriminate between the normal changes due to age and the effect of the disease and to determine the impact of the disease duration.

RESULTS

The initial search identified 752 records, of which 17 were included in the meta-regression. Patients with T1DM had, on average, 193 cells/mm2 lesser than control patients (P < 0.00001). Patients with T2DM had 151 cells/mm2 less compared with control patients (P < 0.00001). The loss of corneal endothelial cells was expected because the aging was similar in patients with T1DM and T2DM and their control groups. Patients with T1DM and T2DM showed an increase in pachymetry versus control patients, and in both groups, it was associated with the duration of the disease.

CONCLUSIONS

Both types of DM reduced CED and increased pachymetry. These differences were higher in patients with T1DM versus control patients than patients with T2DM versus control patients. In T1DM, CED reduction was not correlated with the time from diagnosis. In both groups, patients had CED reduction due to aging similar to that of their matched control patients.

Transcriptional Network Analysis Reveals the Role of miR-223-5p During Diabetic Corneal Epithelial Regeneration

Diabetes mellitus (DM) is a complex metabolic disorder. Long-term hyperglycemia may induce diabetic keratopathy (DK), which is mainly characterized by delayed corneal epithelial regeneration. MicroRNAs (miRNAs) have been reported to play regulatory roles during tissue regeneration. However, the molecular mechanism by which miRNAs influence epithelial regeneration in DK is largely unknown. In this study, we performed miRNA and mRNA sequencing of regenerative corneal epithelium tissue from streptozotocin-induced type 1 diabetic (T1DM) and wild-type mice to screen for differentially expressed miRNAs and mRNAs. Based on regulatory network analysis, miR-223-5p was selected for subsequent experiments and Hpgds was then identified as a direct target gene. MiR-223-5p downregulation significantly promoted diabetic corneal epithelial wound healing and nerve regeneration. However, the beneficial effects of miR-223-5p inhibition were abolished by an Hpgds inhibitor. Furthermore, mechanistic studies demonstrated that miR-223-5p suppression ameliorated inflammation and enhanced cell proliferation signaling in DK. Taken together, our findings revealed that the regulatory role of miR-223-5p in diabetic corneal epithelial and nerve regeneration by mediating inflammatory processes and cell proliferation signaling. And silencing miR-223-5p may contribute to the development of potential therapeutic strategies for DK.

The effect of diabetes on corneal endothelium: a meta-analysis

BACKGROUND

This research was conducted with the aim to determine the effect of diabetes mellitus on corneal endothelial cells.

METHODS

The terms: ("diabetes mellitus" or "diabetes" or "diabetic") and ("corneal endothelium" or "cornea" or "Corneas") searched in Pubmed, Embase, Cochrane, and Web of science until August 2019. The included types of studies contained observational studies. The standard mean difference (SMD) which was deemed as main size effects for continuous data was calculated by means and standard deviations. The data on corneal endothelial cell density (ECD), mean cell area (MCA), cell area variation coefficient (CV) and percentage of hexagonal cells (HEX) included in the study were collected and analyzed using stata15.1.

RESULTS

The final 16 cross-sectional studies and 2 case-control studies were included for the meta-analysis. Meta-analysis revealed that diabetes mellitus could reduce ECD (SMD = - 0.352, 95% CI -0.538, - 0.166) and the HEX (SMD = - 0.145, 95% CI -0.217, - 0.074), in addition to increasing CV (SMD = 0.195, 95% CI 0.123, 0.268). Nevertheless, there was no statistically significant differences observed when combining MCA (SMD = 0.078, 95% CI -0.022, 0.178). In subgroup analysis, Type 2 diabetes patients owned less corneal ECD (P < 0.05). Moreover the same results also found during the subgroup form Asia, Europe and American. The meta-regression revealed the type of diabetes mellitus might be contributing to heterogeneity. (P = 0.008). The results indicated a significant publication bias for studies, with combined CV (Begg's test, P = 0.006; Egger's test, P = 0.005) and merged combined HEX (Begg's test, P = 0.113; Egger's test, P = 0.024).

CONCLUSIONS

As indicated by meta-analysis, diabetes mellitus could cause a detrimental effect on corneal endothelium health. Diabetes mellitus contributed to the instability of corneal endothelium during the analysis. Therefore, further research is considered necessary to confirm our research results.

TRIAL REGISTRATION

CED 42019145858 .

Non-contact specular microscopy with Topcon instruments to assess central corneal thickness of healthy human eyes - A 20 year review

BACKGROUND

The purpose of this review was to evaluate the consistency of central corneal thickness (CCT) values reported with use of Topcon SP-2000 P and SP-3000 P non-contact specular microscopes since their introduction in 1999 with the two microscopes having been commonly used in a wide range of studies.

METHODS

As a primary resource, PubMed was used to search for peer-reviewed articles in any language that included CCT values obtained with non-contact specular microscopy reported for humans with nominally healthy corneas. Relevant articles were obtained and any cited publications also checked.

RESULTS

A total of 76 articles were identified which reported CCT on different small-to-moderate sized groups of individuals, published between 1999 and 2019. From these, an overall group mean CCT value of 0.525 ± 0.013 mm (median 0.525 mm) can be calculated. An estimated 95 % confidence interval (CI, based on 1.96 SD) would be between 0.500 and 0.550 mm. For the two Topcon models, the group mean ± SD values were 0.529 ± 0.013 mm and 0.517 ± 010 mm respectively. An assessment of the CCT data sets in relation to the reported average age indicated no statistically significant effect (p = 0.289, r = -0.129). Very similar average CCT values were also encountered in 4 other reports where these microscopes were used in large-scale population studies as well as in 2 other reports using the newer Topcon SP-1 P model.

CONCLUSIONS

The Topcon stand-alone non-contact specular microscopes have yielded consistent and predictable corneal thickness measures over many years.

The effect of high-fat diet-induced metabolic disturbance on corneal neuroimmune features

PURPOSE

The highly innervated cornea is susceptible to nerve loss secondary to systemic diseases such as diabetes and metabolic disturbances caused by high-fat diet. In this study, we characterize the effect of high-fat diet on the mouse corneal neuroimmune phenotype, including changes to corneal nerve density and resident immune cells, alongside the clinical assessment of corneal thickness and endothelial cell density.

METHODS

Male C57Bl6/J mice, aged 10 weeks, were fed a high-fat diet (60 kcal% fat, 5.2 kcal/g) or control diet (10 kcal%, 3.8 kcal/g) for 16 weeks. At the study endpoint, metabolic parameters (HbA1c, weight, fasting glucose, body fat) were measured to confirm metabolic disturbance. Clinical imaging of the anterior segment was performed using optical coherence tomography to measure the corneal epithelial and stromal thickness. Corneal sensory nerves were visualized using flatmount immunostaining and confocal microscopy. The topographical distribution and density of sensory nerves (BIII-tubulin⁺), intraepithelial CD45⁺ and MHC- II⁺ cells, stromal macrophages (IBA1⁺CD206⁺) and endothelial cells (ZO-1⁺) were analysed using FIJI.

RESULTS

High-fat diet mice had significantly higher blood HbA1c, higher body weight, a higher percentage of body fat and elevated fasting glucose compared to the control diet mice. Corneal epithelial and stromal thickness was similar in both groups. The sum length of the basal nerve plexus was lower in the central and peripheral cornea of mice fed a high-fat diet. In contrast, the sum length of superficial nerve terminals was similar between groups. Epithelial immune cell density was two-fold higher in the central corneas of high-fat diet mice compared to control diet mice. IBA1⁺CD206⁺ macrophage density was similar in the anterior stroma of both groups but was significantly higher in the posterior stroma of the peripheral cornea in the high-fat diet mice compared to controls. The percentage of nerve-associated MHC-II⁺ cells in the epithelium and stroma was higher in HFD mice compared to controls. Endothelial cell density was similar in the corneas of high-fat diet mice compared to controls.

CONCLUSION

Together with corneal neuropathy, corneal immune cells in mice fed a high-fat diet were differentially affected depending on their topographical distribution and location within cornea, and appeared in closer proximity to epithelial and stromal nerves, suggesting a local neuroimmune disruption induced by systemic metabolic disturbance.

The Effect of Diabetes Mellitus on Corneal Endothelial Cells and Central Corneal Thickness: A Case-Control Study

PURPOSE

The aim of this study was to evaluate the characteristics of corneal endothelial cells and central corneal thickness (CCT) in patients with diabetes mellitus (DM), comparing them with those of healthy subjects (controls) and to determine potential factors affecting the corneal parameters in patients with DM.

METHODS

Participants in this study were 72 patients with DM and 88 healthy controls. Diabetic patients were further classified into groups depending on the severity of diabetic retinopathy (no retinopathy, mild, moderate, severe non-proliferative diabetic retinopathy, and proliferative diabetic retinopathy). All participants underwent non-contact specular microscopy to evaluate corneal endothelium parameters and CCT, while factors affecting endothelial cell density and CCT in patients with DM were also analyzed.

RESULTS

Patients with DM presented significantly decreased endothelial cell density compared to controls (2,297.9 ± 311.3 and 2,518.3 ± 243.7 cells/mm2, respectively; p < 0.001), while the two groups did not differ significantly in any other measured corneal parameter. In the diabetic group, the multivariate analysis showed a significant association between decreased endothelial cell density and increased HbA1c (p < 0.001), longer DM duration (p = 0.003), and more severe diabetic retinopathy status (p = 0.008).

CONCLUSION

DM seems to affect the corneal endothelium, since endothelial cell density was decreased in the diabetic group, while duration of disease, HbA1c levels, and severity of retinopathy were significantly associated with changes in endothelial cell density and should be taken into account.

The effects of diabetes mellitus on the corneal endothelium: A review

The corneal endothelium plays a critical role in maintaining corneal clarity. There is an expected decline in cell density with age and disease, and maintaining the health of this cell layer is important as corneal endothelial cells generally are amitotic in vivo. Diabetes mellitus is a highly prevalent disease that damages the corneal endothelium. Diabetes causes structural and functional impairments in the corneal endothelium that decrease cellular reserve in response to stress. These effects have implications to consider for diabetic patients undergoing anterior segment surgery, and for corneal surgeons who use diabetic donor tissue and treat diabetic patients. In this review, we discuss the specifics of how diabetes mellitus impacts the corneal endothelium including alterations in cell morphology, cell density, ultrastructure, pump and barrier function, cataract surgery outcomes, and corneal transplant outcomes with attention to the use of diabetic donor tissue and diabetic transplant recipients.

Corneal thickness and endothelial cell density in children with type 1 diabetes mellitus

BACKGROUND:

The aim of this study was to detect the effect of diabetes on the corneal endothelium in patients of Type 1 diabetes in the pediatric age group and to compare them with age-matched controls. Further, it was proposed to establish any correlation between these changes and risk factors of diabetes, viz., age, duration of diabetes, and hemoglobin A1c (HbA1c) values.

MATERIALS AND METHODS:

This was a prospective cross-sectional study. Fifty children with Type 1 diabetes, between the ages of 7 and 17 years (average, 12.16 ± 2.63 years), and fifty healthy age-matched controls (average 12.28- ±3.00 years) were examined. The central corneal thickness (CCT) and endothelial cell density (CD) were assessed by the Topcon SP-1P specular microscope. The duration of diabetes (average, 3.91 ± 1.65 years) and the HbA1c values (average, 10.92 ± 2.28) were also noted.

RESULTS:

The average CCT in the diabetics was 525.16 ± 33.14 μ and in the controls 513.44 ± 29.46 μ. This was significantly higher (P = 0.015). The average endothelial CD in the diabetics was 3039.64 ± 292.84 cells/mm² and in the nondiabetics 3360.41 ± 268.04 cells/mm². This was significantly lower (P < 0.001). A significant correlation was found between the endothelial CD and age of the diabetic patients (P = 0.008). However, there was no significant correlation between the endothelial CD and the CCT with either duration of diabetes or HbA1c.

CONCLUSIONS:

A significant decrease in the endothelial CD and increase in the CCT occurs in children and adolescents with Type 1 diabetes. With the age of the diabetic patients, the endothelial CD significantly reduces. However, duration of diabetes and HbA1c do not affect these values.

Corneal alteration and pathogenesis in diabetes mellitus

The incidence of diabetes mellitus (DM) and its complications have increased considerably worldwide. Diabetic keratopathy is the major complication of the cornea characterized by delayed corneal wound healing, decreasing corneal epithelial sensitivity, and recurrent corneal ulcers. There is accumulating evidence that diabetic keratopathy is correlated with the hyperglycemic state. Different corneal components may produce different alterations under hyperglycemia. In addition, diabetic nerve alteration may become a novel biomarker of early-stage DM. Abnormalities of the corneal nerve plexus have been associated with diabetic inflammatory states. There is rapidly growing evidence based on investigations of diabetic corneal nerves through in vivo confocal microscopy. Understanding the molecular pathogenesis caused by hyperglycemia may assist in the identification of novel biomarkers, as well as therapeutic targets for early treatment. This review mainly summarizes recent findings on corneal alteration and pathogenesis in DM.

Comparison of Corneal Parameters of Children with Diabetes Mellitus and Healthy Children

Purpose

To compare differences in central corneal thickness (CCT), corneal curvature, and other corneal measurements of children with diabetes mellitus (DM) and healthy children, and to investigate related factors.

Methods

This was a case-control study. From January to February 2018, 50 children with diabetes mellitus were selected as a case group, and 46 healthy children and adolescents without diabetes mellitus were selected as a control group. Corneal topography and CCT were analyzed using a corneal topography measuring apparatus and biometrics (IOL Master). In the diabetic group, we analyzed whether age, course of disease, sex, glycosylated hemoglobin, triglyceride level, total cholesterol, body mass index (BMI), parental BMI, birth history, feeding history, pregnancy, or puerperal history were related to corneal morphology.

Results

There was a significant difference in CCT between groups, but no significant differences were found in corneal diameter, corneal curvature R1 or R2, or corneal topography. Central corneal thickness was not correlated with other clinical factors in the diabetes group.

Conclusion

Early screening and close follow-up of keratopathy in children with diabetes are imperative.

Long noncoding RNA KCNQ1OT1 induces pyroptosis in diabetic corneal endothelial keratopathy

Diabetic corneal endothelial keratopathy is an intractable ocular complication characterized by corneal edema and endothelial decompensation, which seriously threaten vision. It has been suggested that diabetes is associated with pyroptosis, a type of programmed cell death via the activation of inflammation. Long noncoding RNA KCNQ1OT1 is commonly associated with various pathophysiological mechanisms of diabetic complications, including diabetic cardiomyopathy and diabetic retinopathy. However, whether KCNQ1OT1 is capable of regulating pyroptosis and participates in the pathogenesis of diabetic corneal endothelial keratopathy remains unknown. The aim of this study was to investigate the mechanisms of KCNQ1OT1 in diabetic corneal endothelial keratopathy. Here, we reveal that KCNQ1OT1 and pyroptosis can be triggered in diabetic human and rat corneal endothelium, along with the high glucose-treated corneal endothelial cells. However, miR-214 expression was substantially decreased in vivo and in experiments with cultured cells. LDH assay was also used to verify the existence of pyroptosis in high glucose-treated cells. Bioinformatics prediction and luciferase assays showed that KCNQ1OT1 may function as a competing endogenous RNA binding miR-214 to regulate the expression of caspase-1. To further analyze the KCNQ1OT1-mediated mechanism, miR-214 mimic and inhibitor were introduced into the high glucose-treated corneal endothelial cells. The results showed that upregulation of miR-214 attenuated pyroptosis; conversely, knockdown of miR-214 promoted it. In addition, KCNQ1OT1 knockdown by a small interfering RNA decreased pyroptosis factors expressions but enhanced miR-214 expression in corneal endothelial cells. To understand the signaling mechanisms underlying the prepyroptotic properties of KCNQ1OT1, si-KCNQ1OT1 was cotransfected with or without miR-214 inhibitor. The results showed that pyroptosis was repressed after silencing KCNQ1OT1 but was reversed by cotransfection with miR-214 inhibitor, suggesting that KCNQ1OT1 mediated pyroptosis induced by high glucose via targeting miR-214. Therefore, the KCNQ1OT1/miR-214/caspase-1 signaling pathway represents a new mechanism of diabetic corneal endothelial keratopathy progression, and KCNQ1OT1 could potentially be a novel therapeutic target.

An Update on Corneal Biomechanics and Architecture in Diabetes

In the last decade, we have witnessed substantial progress in our understanding of corneal biomechanics and architecture. It is well known that diabetes is a systemic metabolic disease that causes chronic progressive damage in the main organs of the human body, including the eyeball. Although the main and most widely recognized ocular effect of diabetes is on the retina, the structure of the cornea (the outermost and transparent tissue of the eye) can also be affected by the poor glycemic control characterizing diabetes. The different corneal structures (epithelium, stroma, and endothelium) are affected by specific complications of diabetes. The development of new noninvasive diagnostic technologies has provided a better understanding of corneal tissue modifications. The objective of this review is to describe the advances in the knowledge of the corneal alterations that diabetes can induce.

Diabetes and Phacoemulsification Cataract Surgery: Difficulties, Risks and Potential Complications

Diabetes mellitus is one of the most prevalent chronic diseases worldwide. Diabetic patients are at risk of developing cataract and present for surgery at an earlier age than non-diabetics. The aim of this study was to review the problems associated with cataract surgery in a diabetic patient. Corneal complications in diabetic patients include delayed wound healing, risk of developing epithelial defects or recurrent erosions due to the impairment of epithelial basement membranes and epithelial-stromal interactions. Diabetic patients present lower endothelial cell density and their endothelium is more susceptible to trauma associated with cataract surgery. A small pupil is common in diabetic patients making cataract surgery technically challenging. Finally diabetic patients have an increased risk for developing postoperative pseudophakic cystoid macular edema, posterior capsule opacification or endophthalmitis. In patients with pre-proliferative or proliferative diabetic retinopathy, diabetic macular edema or iris neovascularization adjunctive therapy such as an intravitreal anti-vascular endothelial growth factor injection, can inhibit exacerbation related to cataract surgery.

Measurement of corneal thickness, optic nerve sheath diameter and retinal nerve fiber layer as potential new non-invasive methods in assessing a risk of cerebral edema in type 1 diabetes in children

AIMS

Some patients with diabetic ketoacidosis develop cerebral edema (CE) in the course of type 1 diabetes mellitus (T1D), which may result in central nervous system disorders and high mortality. The imperfection of existing neuroimaging techniques for early recognition of CE forces us to search for the new and non-invasive methods. The aim of the study was to assess the usefulness of new methods (pachymetry, transorbital ultrasonography-USG, optical coherence tomography-OCT study) in the assessment of the risk of CE occurrence in children with newly diagnosed T1D.

METHODS

The study group included 50 children with newly diagnosed T1D, 54 patients with long-term T1D as a reference group and 40 children without glucose tolerance disorders as controls. In all subjects, a corneal thickness (CCT) index with pachymeter, optic nerve sheath diameter (ONSD) using transorbital USG and retinal nerve fiber layer (RNFL) during OCT study were measured and compared with selected clinical parameters of T1D.

RESULTS

In patients from a study group at onset of T1D, the higher CCT (p < 0.001) and ONSD (p < 0.001) values were observed as compared to the results obtained after 48 h of metabolic compensation. The ONSD correlated negatively with pH value (r = - 0.64; p < 0.001), BE (r = - 0.54, p < 0.001) and HCO^3- (r = - 0.50; p < 0.001). A positive correlation between RNFL and Na⁺ levels (r = 0.47; p < 0.005) was also observed.

CONCLUSIONS

Transorbital USG and pachymetry may serve as the potential promising methods for the non-invasive assessment of the increased risk of development of CE in patients with T1D.

Diabetic corneal neuropathy: clinical perspectives

Diabetic keratopathy is characterized by impaired innervation of the cornea that leads to decreased sensitivity, with resultant difficulties with epithelial wound healing. These difficulties in wound healing put patients at risk for ocular complications such as surface irregularities, corneal infections, and stromal opacification. Pathological changes in corneal innervations in diabetic patients are an important early indicator of diabetic neuropathy. The decrease in corneal sensitivity is strongly correlated with the duration of diabetes as well as the severity of the neuropathy. This review presents recent findings in assessing the ocular surface as well as the recent therapeutic strategies for optimal management of individuals with diabetes who are susceptible to developing diabetic neuropathy.

Comparison of corneal morphological characteristics between diabetic and non diabetic population

Objective:

To compare corneal morphological parameters between diabetics and age matched non-diabetic control subjects and to evaluate the correlation of these parameters in relation to duration of diabetes mellitus (DM), glycemic status and severity of diabetic retinopathy.(DR).

Methods:

This cross sectional comparative study was conducted at the Department of Ophthalmology, PNS Shifa Karachi from February 2016 to January 2017. Patients with ages between 10 to 80 years of either gender who were diagnosed to have DM were recruited in the study. Control group comprised of age matched healthy volunteers who did not have DM. Corneal morphological parameters (CED, Average cell size, CV of cell size and hexagonality) was evaluated in each subject with non-contact specular microscope and findings were endorsed on a pre devised proforma.

Results:

Data of 298 eyes (149 diabetic patients and 149 healthy controls) was evaluated. Mean corneal endothelial cell density (CED) of diabetic population was 2494.47 ± 394.10 cells/mm², while mean CED of control group was 2574.46 ± 279.97 cells/mm² [p = 0.04]. Between group differences in mean average cell size, CV of cell size and hexagonality was statistically not significant. Analysis of corneal endothelial parameters among subgroups of patients with no DR, with NPDR and PDR did not show statistically significant difference. Moreover, patients with diabetes of more than 10 years duration had significantly lower CED (p <0.01) and larger average cell size (p= 0.03). Duration of DM was significantly correlated with type of DR, HbA1c level, CED, polymegethism and hexagonality.

Conclusion:

Mean corneal endothelial cell density (CED) was found to be significantly lower in diabetic population as compared to healthy controls.

On the regional variability of averaged cell area estimates for the human corneal endothelium in relation to the extent of polymegethism

Purpose

To assess variability in the coefficient of variation (COV) in cell area estimates when using different numbers of cells for endothelial morphometry.

Methods

Using non-contact specular microscopy images of the corneal endothelium, 4 sets of 20 cases were selected that included 200 cells and had overall (global) COV values of less than 30 (group 1), 31–40 (group 2), 41–50 (group 3) and over 50% (group 4). Subjects could be normal, or had ophthalmic disease (such as diabetes), a history of rigid or soft contact lens wear or were assessed after cataract surgery. A step-wise analysis was undertaken, 20 cells at a time, of the variability in cell area estimates when using different numbers of cells for the calculations.

Results

Variability in the average cell area values was higher if only 20–60 cells were used in the calculations and then tended to decrease. The standard deviation values on these average cell area values and the calculated COV showed the same overall trends and were more than twice as large for endothelia with marked polymegethism. Using more than 100 cells/image in markedly polymegethous endothelia only increased the variability in the calculations.

Conclusions

These analyses indicate that substantial region variability in cell area values can be expected in polymegethous endothelia. The analysis further confirm that using only small numbers of cells (e.g. less than 50/image) in such cases is likely to yield far less reliable estimates of COV.

Age-Stratified Analysis of Diabetes and Pseudophakia Effects on Corneal Endothelial Cell Density: A Retrospective Eye Bank Study

PURPOSE

To perform an age-stratified analysis of the effect of diabetes and pseudophakia on corneal endothelial cell density (ECD).

METHODS

This is a comparative analysis of donor characteristics from data supplied by the Lions Eye Institute for Transplant and Research on tissue harvested from July 1, 2007, through May 23, 2014. The mixed-effects model was used to compare age-adjusted mean corneal ECD between donors with and without diabetes.

RESULTS

A total of 20,026 nondiabetic donor eyes and 13,617 diabetic donor eyes were included in this study. ECD was 2604 cells per square millimeter in nondiabetic corneas and 2576 cells per square millimeter in diabetic corneas (P < 0.001). Among phakic patients, diabetic ECD was significantly less in the middle-age subgroups: -33 cells per square millimeter in the 21-to-40-year-old subgroup (P = 0.048) and -25 cells per square millimeter in the 41-to-60-year-old subgroup (P = 0.009). Among pseudophakic patients, diabetic ECD was significantly less only in the subgroup 61 years or older: -56 cells per square millimeter (P = 0.026). The magnitude of difference in ECD between phakic and pseudophakic donors was greater in patients with diabetes in the subgroup 61 years or older (P < 0.001).

CONCLUSIONS

Donor eyes with a history of diabetes had a slightly lower ECD (-29 cells/mm) than eyes without a history of diabetes. Although this statistical relationship is consistent with our pathophysiologic understanding of diabetes and the corneal endothelium, such a minor difference in ECD would be expected to have minimal clinical impact on overall corneal endothelial function.

Further Analysis of the Predictability of Corneal Endothelial Cell Density Estimates When Polymegethism Is Present

PURPOSE

To assess variability in endothelial cell density (ECD) estimates when polymegethism (variance in cell areas) is present.

METHODS

Using noncontact specular microscope images of the corneal endothelium, 4 sets of 20 cases were selected, which included 200 cells and had coefficient of variation values of less than 30% (group 1), 31%-40% (group 2), 41%-50% (group 3), and over 50% (group 4). A stepwise analysis was undertaken, 20 cells at a time, of the ECD estimates when using different numbers of cells for the calculations.

RESULTS

The net differences in ECD estimates when comparing sets of 20 cells with 200 cells were 5.0% ± 3.9%, 8.1% ± 7.3%, 11.3% ± 9.4%, and 14.5% ± 12.4% for groups 1 to 4, respectively. For measures on 100 cells per image, the predicted variances in ECD values were 5.6%, 8.8%, 11.1%, and 13.7% for the 4 groups.

CONCLUSIONS

Higher values of corneal endothelial polymegethism result in predictable increases in the variability (uncertainty) in ECD estimates, thus reducing the "accuracy" of ECD values. There is no obvious utility in assessing more than 100 cells in such endothelia.

A systematic review on the impact of diabetes mellitus on the ocular surface

Diabetes mellitus is associated with extensive morbidity and mortality in any human community. It is well understood that the burden of diabetes is attributed to chronic progressive damage in major end-organs, but it is underappreciated that the most superficial and transparent organ affected by diabetes is the cornea. Different corneal components (epithelium, nerves, immune cells and endothelium) underpin specific systemic complications of diabetes. Just as diabetic retinopathy is a marker of more generalized microvascular disease, corneal nerve changes can predict peripheral and autonomic neuropathy, providing a window of opportunity for early treatment. In addition, alterations of immune cells in corneas suggest an inflammatory component in diabetic complications. Furthermore, impaired corneal epithelial wound healing may also imply more widespread disease. The non-invasiveness and improvement in imaging technology facilitates the emergence of new screening tools. Systemic control of diabetes can improve ocular surface health, possibly aided by anti-inflammatory and vasoprotective agents.

Corneal Endothelial Morphology in Children with Type 1 Diabetes

Aim. To investigate corneal endothelial cell morphological in children with type 1 diabetes and to determine the systemic and local factors that contribute to these changes. Methods. One hundred sixty eyes of 80 children with type 1 diabetes and 80 eyes of 40 normal children as a control during the period from July 2015 to February 2016 underwent full clinical and ophthalmologic examination. We measured the central corneal thickness (CCT), endothelial cell density (ECD), ploymegathism, and pleomorphism using a noncontact specular microscope. Results. The mean age of the diabetic children was 8.22 ± 3.11 years. The mean duration of type 1 diabetes was 3.51 ± 2.23 years. The mean CCT was significantly higher: 537 ± 33.41 microns (right eye), in the diabetic group compared to the control group. The mean ECD in patients with type 1 diabetes was 3149.84 ± 343.75 cells/mm(2) (right eye), and it was significantly lower than in the control group. Furthermore, pleomorphism was significantly lower 48.73 ± 5.43% (right eye), in the diabetic group compared to the control group. The mean polymegathism was significantly higher 37.96 ± 5.61% (right eye), in the diabetic group compared to the control group. All of these changes are significantly correlated only with the duration of diabetes. Conclusions. Diabetic children have thicker corneas, lower ECD, an increased polymegathism, and a decreased pleomorphism. The duration of diabetes is the factor that affects all of these changes. To what extent these changes affect visional function on long term needs to be investigated in further studies.

Corneal oedema after phacoemulsification in the early postoperative period: A qualitative comparative case-control study between diabetics and non-diabetics

Background

The occurrence and severity of corneal oedema after phacoemulsification is dependent on the integrity of corneal endothelial cells. The function of these cells is affected by diabetes mellitus and consequently the behaviour of the cornea in diabetic patients is of special interest.

Aim

To compare the frequency of corneal oedema in two age-matched groups of diabetics and non diabetic patients that underwent cataract surgery in the Ophthalmology Department of Xanthi General Hospital in Greece.

Methods

A retrospective case control study was conducted in a retrospective fashion. Patients in the control and study groups were assessed regarding the severity of corneal oedema at three postoperative visits: days 1, 3–7, 10–14 after the operation. Ultrasound energy consumed during phacoemulsification was also a parameter of interest and possible correlations with the pre-existent cataract severity and the subsequent incidence of corneal oedema were investigated.

Results

The difference in the incidence of severe corneal oedema between the study and control group was statistically significant: (4.5% non diabetics vs 14.3% diabetics). The consumed ultrasound energy did not define final clinical outcome.

Conclusions

The existence of diabetes mellitus type 2 appears to be a significant risk factor for the development of persistent corneal oedema. The results of our study led to the modification of the algorithm for postoperative follow-up of patients of this remote area of Greece.

•

Ultrasound energy is not the only defining factor for the development of corneal oedema.

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Persistent corneal oedema is more frequent in diabetic patients 2 weeks postoperatively.

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Modern Greek public health system requires modifications in clinical governance issues.

Changes in Choroidal Thickness and Corneal Parameters in Diabetic Eyes

Purpose

To evaluate the effect of diabetes mellitus (DM) on central corneal thickness (CCT), corneal endothelial parameters (endothelial cell density [ECD], average size [AVE], hexagonality [A6], polymegathism [SD]), and subfoveal choroidal thickness (SFCT), and to determine whether these parameters depend on the duration of DM and hemoglobin A1c (HbA1c) level.

Methods

A total of 62 patients with type 2 DM and 65 healthy subjects were examined using a noncontact specular microscope, A-scan ultrasound, and spectral-domain optical coherence tomography. The study parameters included medical history, age, eye axial length, CCT, ECD, AVE, A6, SD, and SFCT. The duration of DM and HbA1c level of the 2 latest tests were noted.

Results

The SFCT (258.0 ± 74.4 µm) and ECD (2721.8 ± 264.1 cells/mm2) were significantly lower, and the CCT (566.7 ± 35.7 µm) higher, in diabetic patients than in the control group (313.1 ± 88.5 µm, 2967.3 ± 220.6 cells/mm2, 550.0 ± 56.4 µm, respectively) (p<0.05). There were no differences in age, sex, or axial length between the diabetic and control groups (p>0.05). Diabetic retinopathy and macular edema did not influence SFCT significantly (p>0.05). No differences in endothelial parameters between groups and no correlations among HbA1c, duration of DM, and any of the examined parameters were found (p>0.05).

Conclusions

Diabetic patients have thicker corneas, lower ECD, and thinner subfoveal choroid than healthy subjects.

Evaluation of corneal endothelium in adolescents with juvenile glaucoma

Purpose. To evaluate the endothelial cell density (ECD) and central corneal thickness (CCT) in adolescents with juvenile open-angle glaucoma (JOAG) and ocular hypertension (OH) and to investigate the influence of topical antiglaucoma medications on ECD and CCT in adolescents with JOAG. Methods. ECD and CCT were investigated in 66 eyes of 33 adolescents with JOAG. Depending on the topical treatment the eyes were classified into 4 groups: (1) topical carbonic anhydrase inhibitor, (2) prostaglandin analogs, (3) beta-blocker, and (4) CAI-beta-blocker combination. ECD and CCT were also checked in 24 adolescents with OH and in control group (33 persons). Results. ECD was significantly lower in eyes with JOAG (2639.5 cells/mm²) compared with ECD in eyes with OH (2924.5 cells/mm²) and in control group (2955.5 cells/mm²). CCT was 0.554 mm in eyes with JOAG, 0.55 mm in eyes with OH, and 0.544 mm in control group. ECD in patients with JOAG was 2730 cells/mm² (1 group), 2773.5 cells/mm² (2 group), 2539.5 cells/mm² (3 group), and 2551 cells/mm² (4 group). CCT was 0.556 mm in 1 group, 0.558 mm in 2 group, 0.532 mm in 3 group, and 0.544 mm in 4 group. Conclusions. Our findings indicate that JOAG and OH did not affect CCT, but JOAG has influence on ECD in adolescents. There were no significant differences between ECD and CCT of eyes treated with different kinds of antiglaucoma medications.

Current trends in the monitoring and treatment of diabetic retinopathy in young adults

The diagnosis and treatment of diabetic retinopathy (DR) in young adults have significantly improved in recent years. Research methods have widened significantly, for example, by introducing spectral optical tomography of the eye. Invasive diagnostics, for example, fluorescein angiography, are done less frequently. The early introduction of an insulin pump to improve the administration of insulin is likely to delay the development of diabetic retinopathy, which is particularly important for young patients with type 1 diabetes mellitus (T1DM). The first years of diabetes occurring during childhood and youth are the most appropriate to introduce proper therapeutic intervention before any irreversible changes in the eyes appear. The treatment of DR includes increased metabolic control, laserotherapy, pharmacological treatment (antiangiogenic and anti-inflammatory treatment, enzymatic vitreolysis, and intravitreal injections), and surgery. This paper summarizes the up-to-date developments in the diagnostics and treatment of DR. In the literature search, authors used online databases, PubMed, and clinitrials.gov and browsed through individual ophthalmology journals, books, and leading pharmaceutical company websites.