Comparison of the corneal biomechanical properties, optic nerve head topographic parameters, and retinal nerve fiber layer thickness measurements in diabetic and non-diabetic primary open-angle glaucoma

Neurosurgical Intervention for Nerve and Muscle Biopsies

(1) Background: Neurologic and musculoskeletal diseases represent a considerable portion of the underlying etiologies responsible for the widely prevalent symptoms of pain, weakness, numbness, and paresthesia. Because of the subjective and often nonspecific nature of these symptoms, different diagnostic modalities have been explored and utilized. (2) Methods: Literature review. (3) Results: Nerve and muscle biopsy remains the gold standard for diagnosing many of the responsible neurological and musculoskeletal conditions. However, the need for invasive tissue sampling is diminishing as more investigations explore alternative diagnostic modalities. Because of this, it is important to explore the current role of neurosurgical intervention for nerve and muscle biopsies and its current relevance in the diagnostic landscape of neurological and musculoskeletal disorders. With consideration of the role of nerve and muscle biopsy, it is also important to explore innovations and emerging techniques for conducting these procedures. This review explores the indications and emerging techniques for neurological intervention for nerve and muscle biopsies. (4) Conclusions: The role of neurosurgical intervention for nerve and muscle biopsy remains relevant in diagnosing many neurological and musculoskeletal disorders. Biopsy is especially relevant as a supportive point of evidence for diagnosis in atypical cases. Additionally, emerging techniques have been explored to guide diagnostics and biopsy, conduct less invasive biopsies, and reduce risks of worsening neurologic function and other symptoms secondary to biopsy.

Impact of Type 2 diabetes mellitus and insulin use on progression to glaucoma surgery in primary open angle glaucoma

PURPOSE

To investigate outcomes of primary open-angle glaucoma (POAG) patients with and without type 2 diabetes mellitus (T2DM).

METHODS

Retrospective observational study using U.S. nationwide healthcare insurance claims database. Patients ≥40 years old with at least one HbA1c within one year of POAG diagnosis were included. Diabetic factors associated with POAG progression requiring glaucoma surgery were evaluated using multivariable Cox proportional hazards regression models adjusted for demographic, diabetic and glaucoma factors. T2DM diagnosis and use of either oral hypoglycaemic agents or insulin therapy were assessed in association with POAG progression requiring glaucoma surgery.

RESULTS

104,515 POAG patients were included, of which 70,315 (67%) had T2DM. The mean age was 68.9 years (Standard deviation 9.2) and 55% were female. Of those with T2DM, 93% were taking medication (65,468); 95% (62,412) taking oral hypoglycaemic agents, and 34% (22,028) were on insulin. In multivariable analyses, patients with T2DM had a higher hazard of requiring glaucoma surgery (Hazard ratio, HR 1.15, 95% CI 1.09-1.21, p < 0.001). Higher mean HbA1c was also a significant predictor of progression requiring glaucoma surgery (HR 1.02, 95% CI 1.01-1.03, p < 0.001). When evaluating only patients who were taking antidiabetic medication, after adjusting for confounders, insulin use was associated with a 1.20 higher hazard of requiring glaucoma surgery compared to oral hypoglycaemic agents (95% CI 1.14-1.27, p < 0.001), but when stratified by HbA1c, this effect was only significant for those with HbA1c > 7.5%.

CONCLUSIONS

Higher baseline HbA1c, particularly in patients taking insulin may be associated with higher rates of glaucoma surgery in POAG.

Dissecting causal associations of type 2 diabetes with 111 types of ocular conditions: a Mendelian randomization study

Background

Despite the well-established findings of a higher incidence of retina-related eye diseases in patients with diabetes, there is less investigation into the causal relationship between diabetes and non-retinal eye conditions, such as age-related cataracts and glaucoma.

Methods

We performed Mendelian randomization (MR) analysis to examine the causal relationship between type 2 diabetes mellitus (T2DM) and 111 ocular diseases. We employed a set of 184 single nucleotide polymorphisms (SNPs) that reached genome-wide significance as instrumental variables (IVs). The primary analysis utilized the inverse variance-weighted (IVW) method, with MR-Egger and weighted median (WM) methods serving as supplementary analyses.

Results

The results revealed suggestive positive causal relationships between T2DM and various ocular conditions, including "Senile cataract" (OR= 1.07; 95% CI: 1.03, 1.11; P=7.77×10-4), "Glaucoma" (OR= 1.08; 95% CI: 1.02, 1.13; P=4.81×10-3), and "Disorders of optic nerve and visual pathways" (OR= 1.10; 95% CI: 0.99, 1.23; P=7.01×10-2).

Conclusion

Our evidence supports a causal relationship between T2DM and specific ocular disorders. This provides a basis for further research on the importance of T2DM management and prevention strategies in maintaining ocular health.

Association Between Diabetes, Diabetic Retinopathy, and Glaucoma

PURPOSE OF REVIEW

The strength of the relationship between diabetes, diabetic retinopathy (DR), and glaucoma remains controversial. We review evidence supporting and refuting this association and explore mechanistic pathological and treatment relationships linking these diseases.

RECENT FINDINGS

While studies have shown diabetes/DR may increase the risk for glaucoma, this remains inconsistently demonstrated. Diabetes/DR may contribute toward glaucomatous optic neuropathy indirectly (either by increasing intraocular pressure or vasculopathy) or through direct damage to the optic nerve. However, certain elements of diabetes may slow glaucoma progression, and diabetic treatment may concurrently be beneficial in glaucoma management. Diabetes plays a significant role in poor outcomes after glaucoma surgery. While the relationship between diabetes/DR and glaucoma remains controversial, multiple mechanistic links connecting pathophysiology and management of diabetes, DR, and glaucoma have been made. However, a deeper understanding of the causes of disease association is needed.

Is Diabetes Mellitus a Blessing in Disguise for Primary Open-angle Glaucoma?

Although numbers of studies have addressed this question, the relationship between diabetes mellitus and primary open-angle glaucoma is still unclear. This article discusses progress in understanding the complex relationship between these 2 entities and recent shifts in perspective that challenge the traditional dogma regarding diabetes mellitus and primary open-angle glaucoma. There are still many unanswered questions.

Changes in corneal biomechanics in patients with diabetes mellitus: a systematic review and meta-analysis

AIMS

To determine the changes in corneal biomechanical parameters in patients with diabetes mellitus (DM) in comparison with controls.

METHODS

Pertinent studies were identified by comprehensively search of PubMed, Embase, the Web of Science, the Cochrane Library, Scopus, the China National Knowledge Infrastructure and the Chinese biomedical disc (CBM) databases. Pooling analyses by random models using the D-L method were performed for corneal hysteresis (CH), the corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOPg).

RESULTS

A total of 15 studies were included in the final analysis, involving 1506 eyes in the diabetic group and 2190 eyes in the control group. The diabetic group had significantly higher CH, CRF, IOPg and IOPcc values than the control group. The pooled mean differences were 1.34 mmHg (95% confidence interval [CI] 0.60-2.08 mmHg, P < 0.001) for IOPg and 0.85 mmHg (95% CI 0.18-1.51 mmHg, P = 0.013) for IOPcc, 0.38 mmHg (95% CI 0.01-0.75, P = 0.047) for CH and 0.63 mmHg (95% CI 0.27-0.98, P = 0.001) for the CRF. Sensitivity analyses using the leave-one-out method showed a consistent significant difference between the groups (all P < 0.001).

CONCLUSIONS

Corneal biomechanics changed in the patients with DM. High CH, CRF, IOPcc and IOPg values may be associated factors for diabetes mellitus. Future studies are warranted to clarify the underlying mechanisms and explore the relationship between corneal biomechanics, glaucoma and diabetes mellitus.

REGISTRATION

PROSPERO registration No CRD4201705465.

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.

Progression of Primary Open-Angle Glaucoma in Diabetic and Nondiabetic Patients

PURPOSE

To compare the rates of visual field (VF) loss and retinal nerve fiber layer (RNFL) thinning in primary open-angle glaucoma (POAG) patients with or without type 2 diabetes mellitus (DM).

DESIGN

Cohort study.

METHODS

A total of 197 eyes (55 eyes of 32 POAG patients with DM in POAG/DM group and 142 eyes of 111 age-matched POAG patients without DM in POAG/DM- group) were included from the Diagnostic Innovations in Glaucoma Study (DIGS). Type 2 DM participants were defined by self-report of DM history and use of antidiabetic medication. The rates of VF loss and RNFL loss were compared in POAG eyes with and without DM using univariate and multivariable mixed-effects models.

RESULTS

The median (interquartile range) follow-up was 5.7 years (4.0, 6.4). The mean rate of global RNFL loss in the POAG/DM group was 2-fold slower than in the POAG/DM- group overall (-0.40 μm/year vs -0.83 μm/year, respectively P = .01). Although a slower rate of VF mean deviation and pattern standard deviation loss was found in the POAG/DM group compared to the POAG/DM- group, the difference was not statistically significant.

CONCLUSIONS

POAG patients with treated type 2 DM, who had no detectable diabetic retinopathy, had significantly slower rates of RNFL thinning compared to those without diagnosed DM.