Quantitative corneal anatomy: evaluation of the effect of diabetes duration on the endothelial cell density and corneal thickness

Association Between Corneal Changes and Retinal Oximetry in Diabetes Mellitus

Purpose

Diabetes mellitus (DM) causes different corneal changes that are associated with the severity of diabetic retinopathy. To identify the pathophysiological reasons for this, corneal tomography and optical densitometry (COD) were combined with retinal oximetry.

Methods

Patients with DM and healthy subjects were included in this pilot study. Spatially resolved corneal thickness and COD were assessed using the Pentacam HR (Oculus). The pachymetry difference (PACDiff) was calculated as an indicator of an increase in the peripheral corneal thickness. Oxygen saturation (SO2) of the retinal vessels was measured using the Retinal Vessel Analyzer (Imedos Systems UG). Subsequently, the associations between corneal and retinal parameters were analyzed.

Results

Data from 30 patients with DM were compared with those from 30 age-matched healthy subjects. In DM, arterial (P = 0.048) and venous (P < 0.001) SO2 levels were increased, and arteriovenous SO2 difference was decreased (P < 0.001). In patients, PACDiff was higher than that in healthy subjects (P < 0.05), indicating a stronger increase in peripheral corneal thickness. The COD was reduced in DM (P = 0.004). The PACDiff of concentric rings with a diameter of 4 mm (r = -0.404; P = 0.033) to 8 mm (r = -0.522; P = 0.004) was inversely correlated with the arteriovenous SO2 difference. Furthermore, PACDiff 4 mm was negatively associated with arterial SO2 (r = -0.389; P = 0.041), and the COD of the peripheral corneal areas correlated positive with arterial SO2 (COD total 10-12 mm: r = 0.408; P = 0.025).

Conclusion

These associations might indicate a common pathogenesis of corneal and retinal changes in DM, which could be caused by reduced oxygen supply, mitochondrial dysfunction, oxidative stress, and cytokine effects.

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.

Changes in tear glucose and insulin concentrations following an oral glucose tolerance test

CLINICAL RELEVANCE

Tear glucose and insulin are responsible for the health of the ocular surface; thus, it is important for clinicians to detect the tear glucose and insulin using point-of-care methods.

AIM

To determine if changes in blood glucose and insulin levels following an oral glucose tolerance test are reflected in the tears and to test the association between gene expression and tear insulin and glucose.

METHODS

Twenty healthy young adults were enrolled. Basal tears and peripheral blood samples were collected to assess glucose and insulin using a point-of-care glucometer and ELISA assays in fasted subjects, and 1.5 and 3 h after an oral glucose challenge. Conjunctival impression cytology was collected to determine gene expression of insulin receptor (INSR) and glucose transporters (GLUT1 and GLUT4). Changes were examined using non-parametric one-way ANOVA. Spearman tests were conducted to examine associations between variables.

RESULTS

Glucose and insulin levels increased 1.5 h after oral glucose in both blood (P < 0.001) and tears (P < 0.049) and returned to near baseline values after 3 h. There was a positive correlation between glucose levels in the blood and tears (rho = 0.57, P < 0.001), but not between blood and tear insulin levels (P = 0.18). Glucose and insulin levels in tears were correlated (rho = 0.32, P = 0.048). Tear glucose concentration at 1.5 h after oral glucose was associated with INSR expression (rho = 0.49, P = 0.03), and there was a trend with GLUT1 (P = 0.06) but not GLUT4.

CONCLUSION

Tear glucose reflected blood glucose levels but this correspondence was not observed for insulin. Further studies are required to determine the role of glucose and insulin on the ocular surface in both health and diabetes.

Meta-analysis of corneal endothelial changes after phacoemulsification in diabetic and non-diabetic patients

BACKGROUND

Currently, there is still controversy about the differential changes in corneal endothelium function and morphology after phacoemulsification between Diabetes Mellitus (DM) and non-Diabetes Mellitus (non-DM) patients. In this study, we aimed to evaluate the influence of phacoemulsification on the corneal endothelium in DM and non-DM patients.

METHODS

Databases of PubMed, Embase, Web of Science, and the Cochrane Library were searched for studies published between January 1, 2011 and December 25, 2021. The weighted mean difference and 95% confidence interval were used to estimate the outcomes of statistical analyses performed.

RESULTS

Thirteen studies involving 1744 eyes were included in this meta-analysis. No significant difference was observed in the central corneal thickness (CCT), endothelial cell density (ECD), coefficients of variation (CV), or hexagonal cell percentage (HCP) between the DM and non-DM groups (CCT: P = 0.91; ECD: P = 0.07; CV: P = 0.06; HCP: P = 0.09) preoperatively. The CCT was significantly thicker in the DM group at 1 month (P = 0.003) and 3 months (P = 0.0009) postoperatively, and there was no significant difference at 6 months postoperatively (P = 0.26) than non-DM group. The CV was significantly higher and HCP was significantly lower in the DM group at 1 month (CV:P < 0.0001, HCP: P = 0.002), with no significant difference at 3 months (CV: P = 0.09, HCP: P = 0.36) and 6 months (CV: P = 0.32, HCP: P = 0.36) postoperatively than non-DM group. DM patients had lower ECD than non-DM patients at all postoperative time points (1 month, 3 months: P < 0.00001, 6 months: P < 0.0001).

CONCLUSIONS

The influence of phacoemulsification on corneal endothelial damage is greater in diabetic patients. Moreover, the recovery of corneal endothelial function and morphology is delayed in these patients. Clinicians should be more attentive to the corneal health of DM patients when considering phacoemulsification.

Effect of diabetes mellitus on quantitative corneal anatomy – A systemic review

Background: Corneal changes occur as a direct consequence of diabetes mellitus (DM). The central corneal thickness (CCT) is a useful parameter that provides information about the status of the metabolism of the cornea and can therefore help monitor the progression of DM.Aim: The aim of this study was to determine the impact of DM on CCT and its correlation with diabetes duration and glycated haemoglobin (HbA1c) levels.Methods: The systematic review was undertaken to answer: (1) What effect does DM have on CCT values? (2) What effect does DM duration have on CCT values? (3) What effect does HbA1c levels have on CCT values? The Web of Science was used to conduct a computerised search for articles of CCT values in DM.Results: A total of 38 articles that met the criteria for inclusion were included in this systemic review. The researchers found 27 articles that observed increased CCT values in DM patients compared with control subjects. There were six studies in which increased CCT values were related to DM duration and 12 studies in which DM duration did not alter CCT values. Also, eight studies showed that CCT values increased with glycated haemoglobin levels, and 12 studies did not observe this.Conclusion: Diabetes mellitus patients usually present with increased CCT values although there is no unanimity about the effect of DM duration and increased HbA1c levels (poor glycaemic control) in the CCT values of DM patients. 

Pathogenic Role of Endoplasmic Reticulum Stress in Diabetic Corneal Endothelial Dysfunction

Purpose

Progressive corneal edema and endothelial cell loss represent the major corneal complications observed in diabetic patients after intraocular surgery. However, the underlying pathogenesis and potential treatment remain incompletely understood.

Methods

We used streptozotocin-induced type 1 diabetic mice and db/db type 2 diabetic mice as diabetic animal models. These mice were treated with the endoplasmic reticulum (ER) stress agonist thapsigargin; 60-mmHg intraocular pressure (IOP) with the ER stress antagonist 4-phenylbutyric acid (4-PBA); mitochondria-targeted antioxidant SkQ1; or reactive oxygen species scavenger N-acetyl-l-cysteine (NAC). Corneal thickness and endothelial cell density were measured before and after treatment. Human corneal endothelial cells were treated with high glucose with or without 4-PBA. The expression of corneal endothelial- and ER stress–related genes was detected by western blot and immunofluorescence staining. Mitochondrial bioenergetics were measured with an Agilent Seahorse XFp Analyzer.

Results

In diabetic mice, the appearance of ER stress preceded morphological changes in the corneal endothelium. The persistent ER stress directly caused corneal edema and endothelial cell loss in normal mice. Pharmacological inhibition of ER stress was sufficient to mitigate corneal edema and endothelial cell loss in both diabetic mice after high IOP treatment. Mechanistically, inhibiting ER stress ameliorated the hyperglycemia-induced mitochondrial bioenergetic deficits and improved the barrier and pump functional recovery of the corneal endothelium. When compared with NAC, 4-PBA and SkQ1 exhibited better improvement of corneal edema and endothelial cell loss in diabetic mice.

Conclusions

Hyperglycemia-induced ER stress contributes to the dysfunction of diabetic corneal endothelium, and inhibiting ER stress may offer therapeutic potential by improving mitochondrial bioenergetics.

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.

The influence of diabetes mellitus type 2 on the central corneal thickness

Background/Aim. Complications of diabetes mellitus (DM) in the eye are the leading cause of blindness in the world. Although research on eye complications of DM is mainly focused on retinal damage, changes in the cornea are also associated with DM. Central corneal thickness (CCT) reflects the metabolic status of the cornea and is also affected by DM. Knowledge of CCT changes that occur within DM is important for accurate IOP measurement, diagnosis, and monitoring of patients with glaucoma. The aim of the study was to examine the effect of DM type 2 on the central corneal thickness. Methods. The study was designed as a clinical, cross-sectional, observational study. It consists of 96 patients, divided into two groups. The first group consisted of 49 patients diagnosed with DM type 2. The second group was the control group and consisted of 47 healthy subjects. The DM group was divided into subgroups depending on the status of diabetic retinopathy, the length of DM treatment, and the levels of glycosylated hemoglobin (HbA1C). Results. A statistically significant difference in CCT was observed among DM patients and the control group. Analyzing only DM patients, the highest CCT values were observed in patients who had HbA1C > 7.0%, as well as those who have treated DM for more than 15 years, with a statistically significant difference in relation to the corresponding patient sub-groups (p = 0.002 and p = 0.037, respectively). No statistically significant difference was observed depending on the status of retinopathy. Intraocular pressure (IOP) was statistically significantly higher in patients with DM compared to the control group. Conclusion. Our research demonstrated that the status of retinopathy had no statistically significant influence on CCT. Knowing that the increase in CCT also affects the measured IOP values, this research will be useful in better understanding and control of the patients who have glaucoma in addition to DM type 2.

Hyperglycemia induces corneal endothelial dysfunction through attenuating mitophagy

Hyperglycemia increases the risk of corneal endothelial dysfunction, resulting in damage to corneal endothelial structure and function. However, the effect and mechanism of hyperglycemia-induced corneal endothelial damage remain elusive. In this study, we demonstrated that hyperglycemia reduced the expression of pump-related protein Na⁺/K⁺ ATPase and barrier-related protein ZO-1. Moreover, we found hyperglycemia caused abnormal changes of morphological mitochondria and dynamics in vitro. In addition, the decreased levels of mitophagy were further confirmed Western blotting and LC3B-Mitotracker Immunofluorescence. Exogenous application of mitophagy agonist carbonyl cyanide m-chlorophenyl hydrazine (CCCP) increases the expression of Na⁺/K⁺ ATPase and ZO-1 in corneal endothelial cells through up-regulated mitophagy in vitro. In addition, CCCP effectively reverses the phenomenon of corneal opacity and increased corneal thickness in diabetic mice. Therefore, our demonstrated the novel function of mitophagy in the pathogenesis of diabetic cornea endothelial dysfunction, and provide potential approach for treating diabetic corneal endothelial dysfunction.

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.

Epithelial Remodeling Following Phacoemulsification in Diabetic Patients Using Anterior-Segment Optical Coherence Tomography: A Comparative Study

Purpose

To compare the effect of phacoemulsification on corneal epithelial thickness in diabetic and nondiabetic cataract patients.

Methods

Fifty eyes with cataracts were enrolled in a prospective comparative interventional study. They were divided into two groups: group A (diabetics) and group B (nondiabetics) and underwent uneventful phacoemulsification. Epithelial thickness was assessed in the central, paracentral, and peripheral cornea on the first day and at 1 week, 1 month, and 3 months postoperatively using spectral-domain ocular coherence tomography.

Results

A significant increase in the first-day postoperative central epithelial thickness was noticed in both groups (57.16±3.5 µm and 55.96±2.81 µm in groups A and B, respectively), with increased baseline epithelial thickness of 3.8±2.1 µm and 3.4±2.14 µm in groups A and B, respectively (P<0.001). A significant decrease in epithelial thickness was noticed in both groups after 1 week (−2.40±3.1 µm and −2.76±2.71 µm in group A and B, respectively). No further significant change was noticed in the nondiabetic group at 1 month; however, significant reductions in for central epithelial thickness were found in the diabetic group up to the first month (−0.80±1.9 µm, P=0.05). Central corneal thickness followed the same pattern of change as the epithelium. A nonsignificant delay in visual acuity improvement was noticed in diabetic patients.

Conclusion

Phacoemulsification induces a temporary increase in corneal and epithelial thickness that should resolve by the first week postoperatively. However, diabetic patients had slower epithelial recovery that took up to 1 month, which could be reflected in delayed visual recovery with no effect on the final visual outcome.

Evaluation of Corneal Structure and Endothelial Morphological Characteristics in Type 2 Diabetic and Non-Diabetic Patients

Purpose

To compare corneal structure and endothelial morphological features between patients with type 2 diabetes mellitus (DM) and non-diabetic patients; and determine if the DM duration, glycated hemoglobin (HbA1c) levels, and diabetic retinopathy (DR) stage affect corneal morphological properties.

Patients and Methods

Sixty diabetic patients and 47 age- and sex-matched controls were enrolled in this cross-sectional study. DM group was analyzed according disease duration, HbA1c levels, and presence of retinopathy. Endothelial cell density (ECD) and morphology (average and coefficient of variation [CV] of cell size, percentage of hexagonal cells) were recorded using non-contact specular microscopy. Central corneal thickness (CCT) and corneal volume were measured by scheimpflug tomography. Univariate and multivariate linear regression analyses were performed to evaluate the relationship between demographical, clinical, and ocular variables with CCT and ECD.

Results

There were no statistically significant differences in the endothelium cell density or morphology between DM and non-DM groups (p>0.05). Also, there was no statistical difference between groups for CCT or corneal volume (p>0.05). Multivariate linear regression analysis showed that older age (p=0.028) was significantly associated with lower ECD; CCT was found to be significantly greater in males (p<0.001) and positively associated with corneal volume (p<0.001).

Conclusion

The present study did not find any statistically significant differences between the corneal structural and endothelial characteristics of diabetic and non-diabetic subjects; other demographical parameters, such as age and gender, seem to be more determinant for the corneal properties.

Corneal endothelial cell density during diabetes mellitus and ocular diabetes complications treatment

Diabetes mellitus may affect the cornea at various levels. Ocular surface changes and dry eye had been studied. Researchers are concerned that medical treatment of diabetes or retinal complications may result in endothelial damage and cell loss. This report summarizes the possibility of endothelial cell loss in diabetic patients. A decrease in endothelial cell density (ECD) in diabetic patients has been reported. In addition, corneal thickness may increase in diabetic patients. Significant endothelial cell loss has been demonstrated in long-term disease and in cases of poor metabolic control. No association between the use of oral hypoglycemics and ECD has been reported. There is also no evidence of an association between the use of insulin and corneal endothelial damage. No difference in ECD among the various degrees of retinopathy or with a history of photocoagulation has been shown. Regarding the studies comparing diabetic and non-diabetic patients undergoing cataract surgery, in all cases, the decrease in ECD is higher in diabetic patients than that seen in non-diabetic patients. However, there is no evidence of increased endothelial damage in diabetics compared to non-diabetics during vitreo-retinal surgery in phakic eyes. No significant changes in corneal endothelium after intravitreal anti-VEGF injections have been referenced.

Eye care providers' emerging roles in early detection of diabetes and management of diabetic changes to the ocular surface: a review

US adults visit eye care providers more often than primary healthcare providers, placing these doctors in a prime position to help identify and manage patients with prediabetes and diabetes. Currently, diabetes is identified in eye clinics in an advanced stage, only after visible signs of diabetic retinopathy. Recent ophthalmic research has identified multiple subclinical and clinical changes that occur in the anterior segment of the eye with metabolic disease. The corneal epithelium exhibits increased defects and poor healing, including an increased risk of neurotrophic keratitis. Increased thickness and stiffness of the cornea artificially alters intraocular pressure. There is damage to the endothelial cells and changes to the bacterial species on the ocular surface, both of which can increase risk of complications with surgery. Decreased corneal sensitivity due to a loss of nerve density predispose patients with metabolic disease to further neurotrophic complications. Patients with diabetes have increased Meibomian gland dysfunction, blepharitis and reduced tear production, resulting in increased rates of dry eye disease and discomfort. Early detection of metabolic disease may allow eye care providers to be more proactive in recommending referral and intervention in order to reduce the risk of blindness and other diabetes-related morbidity. Continued research is needed to better understand the time course of changes to the anterior segment and what can be done to better detect and diagnose patients with prediabetes or undiagnosed diabetes and provide improved care for these patients.

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.

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.

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.

Scheimpflug Camera and Swept-Source Optical Coherence Tomography in Pachymetry Evaluation of Diabetic Patients

Aim

The comparative analysis of the central and peripheral corneal thicknesses using two different imaging systems: Scheimpflug camera and swept-source OCT was performed to investigate the differences in corneal thickness analysis in diabetic patients.

Materials and Methods

The study group consisted of the 147 eyes of 107 diabetic patients who were examined and compared with 138 eyes of 89 nondiabetic cataract patients. The inclusion criteria for the study group was diabetes mellitus type II identified no less than 10 years ago, with NPDR not requiring prior laser treatment. The control group was recruited from nondiabetic patients. Measurements were obtained on the Pentacam Scheimpflug imaging system and Casia swept-source OCT. All study parameters from anterior chamber images were processed for five different zones, the central zone and four peripherals—superior, inferior, nasal, and temporal. A fit zone diameter of 4 mm was applied for both instruments.

Results

The Pentacam system overestimated corneal measurements in the DM group when compared with the Casia OCT in superior corneal zone (p=0.04), inferior corneal zone (p=0.02), nasal corneal zone (p < 0.001), and temporal corneal zone (p=0.01). In the control group, there were also statistically significant differences between the Pentacam and Casia OCT measured values in inferior corneal zone (p=0.001), nasal corneal zone (p=0.04), and temporal corneal zone (p < 0.001).

Conclusion

Scheimpflug camera pachymetry measurements showed statistically higher CCT values when compared with swept-source OCT measurements.

Effect of Diabetes Mellitus Type 1 Diagnosis on the Corneal Cell Densities and Nerve Fibers

Relation of diabetes mellitus (DM) to the various stages of corneal nerve fiber damage is well accepted. A possible association between changes in the cornea of diabetic patients and diabetic retinopathy (DR), DM duration, and age at the time of DM diagnosis were evaluated. The study included 60 patients with DM type 1 (DM1) and 20 healthy control subjects. The density of basal epithelial cells, keratocytes and endothelial cells, and the status of the subbasal nerve fibers were evaluated using in vivo corneal confocal microscopy. Basal epithelial cell density increased with age (p=0.026), while stromal and endothelial cell density decreased with age (p=0.003, p=0.0005, p<0.0001). After the DM1 diagnosis was established, this association with age weaken. We showed nerve fiber damage in DM1 patients (p˂0.0001). The damage correlated with the degree of DR. DM1 patients with higher age at DM1 diagnosis had a higher nerve fiber density (p=0.0021). These results indicated that age at DM1 diagnosis potentially has an important effect on final nerve fiber and corneal cell density.

Painless bilateral bullous keratopathy

Bullous keratopathy is a pathological corneal condition that arises due to irreversible oedema associated with endothelial cell loss or dysfunction. Symptoms may vary from mild (transient blurred vision and increased glare from epithelial oedema) to severe (an acute and significant loss of vision associated with frank endothelial decompensation, and pain due to ruptured epithelial bullae). Possible treatments to restore vision and minimise pain include topical hypertonic agents, bandage contact lenses, superficial anterior corneal surgical procedures or penetrating full thickness or endothelial keratoplasty. This case report describes a rare presentation of painless, bilateral, asymmetric bullous keratopathy with severe vision loss in an elderly male with non-insulin dependent diabetes mellitus.

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.

Objective Evaluation of Corneal and Lens Clarity in Children With Type 1 Diabetes Mellitus

PURPOSE

To investigate whether abnormal glucose metabolism and duration of diabetes mellitus (DM) affected the corneal and lens clarity in children with well-controlled type 1 DM and to compare the results obtained with those in healthy children.

DESIGN

Cross-sectional prospective study.

METHODS

This multicenter study enrolled 56 patients with DM and 51 control subjects. The duration of DM and the glycosylated hemoglobin (HbA1c) levels of the patients in the DM group were recorded. The Pentacam HR imaging system was used for corneal densitometry (12-mm corneal diameter) measurements. Furthermore, the lens densitometry and lens thickness (LT) measurements were performed after dilation of the pupils, using the same Pentacam HR device.

RESULTS

The corneal densitometry values were similar in all concentric zones and layers in both groups (P > .05, for all). The mean values of the average and maximum lens densitometry measurements of the 2 groups, as well as the mean LT values, were statistically significantly different (P = .021, P = .011, and P < .001, respectively). There were statistically significant correlations between the lens densitometry values and the duration of DM (P < .05, for all). Conversely, no statistically significant relationship was found between the lens densitometry values and HbA1c levels (r = 0.743; P = .084).

CONCLUSIONS

The children with type 1 DM had decreased lens clarity and increased LT, even in cases of well-controlled DM, without DR. It is reasonable to think that these changes might have been caused by the type 1 DM.

Corneal thickness differences between type 2 diabetes and non-diabetes subjects during preoperative laser surgery examination

AIMS

To evaluate the differences in corneal thickness between type 2 diabetes subjects with HbA1c under 7.0% and non-diabetes subjects during their preoperative laser surgery examinations.

METHODS

The mean of five consecutive corneal thickness measurements at the central and mid-peripheral cornea was obtained by means of noncontact scanning-slit corneal topography (Orbscan Topography System II; Orbscan, Inc., Salt Lake City, UT, USA) in 35 myopic non-insulin dependent type 2 diabetes subjects (17 males and 18 females) and 48 healthy myopic controls (23 males and 25 females).

RESULTS

The corneal thickness values at the central and mid-peripheral cornea were significantly higher in the diabetic group (p<.001). The diabetic subjects presented the highest thickness value in the superior cornea (n=22; 62.9%) followed by the nasal (n=9; 25.7%) and the temporal (n=4; 11.4%) cornea, but never in the inferior cornea. The control subjects presented the highest thickness value in the superior cornea (n=19; 39.6%) followed by the nasal (n=18; 37.5%), the inferior (n=6; 12.5%), and the temporal (n=3; 6.3%) cornea. The central corneal thickness (CCT) of the diabetes patients was not statistically correlated with their HbA1c (r²=.078; p=.104), body mass index (r²=.007; p=.633), and time from diagnosis of diabetes (r²=.025; p=.363), but it was correlated with their corneal endothelial cell density values (r²=.543; p<.001).

CONCLUSIONS

Diabetes subjects with HbA1c under 7.0% who are candidates for laser refractive surgery present thicker corneas than their age-matched control subjects. In these patients, there is a correlation between their CCT values and their corneal endothelial cell density values, so when higher CCT values were found, lower corneal endothelial cell density values were observed.

Plasma Lipoprotein-Associated Phospholipase A₂ Levels Correlated with the Cardio-Ankle Vascular Index in Long-Term Type 2 Diabetes Mellitus Patients

The circulating levels of lipoprotein-associated phospholipase A₂ (Lp-PLA₂) can be a simple, but practical and useful marker of cardiovascular disease (CVD). As limited studies are available in patients with diabetes mellitus (DM), further studies are needed to establish the clinical application of Lp-PLA₂ in DM practice. The present study investigated the correlation between Lp-PLA₂ and the cardio-ankle vascular index (CAVI), a recent marker of arterial stiffness, in DM patients according to their diabetes duration. Clinical data, including the plasma Lp-PLA₂ mass and CAVI values, were collected from CVD-free type 2 DM female patients (n = 65, mean age 62 years, mean hemoglobin A1c 7.0%). The Lp-PLA₂ level of patients with a diabetes duration of <10 years (n = 40:20.2 IU/mL) was not significantly different from that of patients with a diabetes duration of ≥10 years (n = 25:20.5 IU/mL), while the CAVI level was significantly higher in patients with ≥10 years (9.0) than in those with <10 years (8.1; p < 0.05). A stepwise multiple regression analysis found a positive correlation between the Lp-PLA₂ and CAVI levels (β = 0.43, p < 0.01) in patients with a diabetes duration of ≥10 years. This correlation between Lp-PLA₂ and CVAI suggests the possible use of Lp-PLA₂ in DM patients with long-term disease. Further studies on Lp-PLA₂ are warranted in DM practice in relation to the disease duration.

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.