Retinal Neurodegeneration in Diabetic Peripheral Neuropathy by Optical Coherence Tomography: A Systematic Review and Meta-analysis

Intravitreal Antiangiogenic Treatment for Diabetic Retinopathy: A Mexican Real-Life Scenario Experience

The objective of this study was to analyze the effectiveness of two intravitreal antiangiogenic drugs, ranibizumab and aflibercept, in a Mexican population over a period of 5 years, evaluating the improvement in visual acuity (VA) and central retinal thickness (CRT) in a real-world scenario. This is a retrospective study with subjects diagnosed with diabetic retinopathy (DR), proliferative diabetic retinopathy (PDR), and diabetic macular edema (DME) receiving intravitreal injections of ranibizumab and/or aflibercept. In this study, we analyzed 588 eyes of 294 patients who received intravitreal antiangiogenic injections. The results showed an improvement regardless of antiangiogenic treatment or diagnosis in both VA and CRT. We found that both aflibercept and ranibizumab improved VA, while subjects with DME responded less to antiangiogenic treatment (p < 0.05), and that this difference did not correspond to the CRT measured by OCT. These results support evidence that intravitreal antiangiogenic medications are effective for ophthalmic complications of diabetes in our population; however, damage to visual structures is not reversed in most patients. And that the perception by the patient (VA) and that of the ophthalmologist (CRT) do not completely correlate in our study.

The Retinal Nerve Fiber Layer Thickness Is Associated with Systemic Neurodegeneration in Long-Term Type 1 Diabetes

Purpose

To determine whether the retinal nerve fiber layer thickness can be used as an indicator for systemic neurodegeneration in diabetes.

Methods

We used existing data from 38 adults with type 1 diabetes and established polyneuropathy. Retinal nerve fiber layer thickness values of four scanned quadrants (superior, inferior, temporal, and nasal) and the central foveal thickness were extracted directly from optical coherence tomography. Nerve conduction velocities were recorded using standardized neurophysiologic testing of the tibial and peroneal motor nerves and the radial and median sensory nerves, 24-hour electrocardiographic recordings were used to retrieve time- and frequency-derived measures of heart rate variability, and a pain catastrophizing scale was used to assess cognitive distortion.

Results

When adjusted for hemoglobin A1c, the regional thickness of the retinal nerve fiber layers was (1) positively associated with peripheral nerve conduction velocities of the sensory and motor nerves (all P < 0.036), (2) negatively associated with time and frequency domains of heart rate variability (all P < 0.033), and (3) negatively associated to catastrophic thinking (all P < 0.038).

Conclusions

Thickness of the retinal nerve fiber layer was a robust indicator for clinically meaningful measures of peripheral and autonomic neuropathy and even for cognitive comorbidity.

Translational Relevance

The findings indicate that the thickness of the retinal nerve fiber layer should be studied in adolescents and people with prediabetes to determine whether it is useful to predict the presence and severity of systemic neurodegeneration.

Prevalence and associated factors of visual impairment among adult diabetic patients visiting Adare General Hospital, Hawassa, South Ethiopia, 2022

BACKGROUND

The increased prevalence of visual impairment among diabetic patients has become a major public health problem. However, there was limited information on the extent of visual impairment among diabetic patients in our country, and there was no study in the study area. Providing updated data regarding this area is critical for the prevention of visual impairment among diabetic patients.

PURPOSE

The study aimed to assess the prevalence and associated factors of visual impairment among adult diabetic patients visiting Adare General Hospital, Hawassa, South Ethiopia, 2022.

METHODS

A hospital-based cross-sectional study was conducted on adult diabetic patients from May 30 to July 15, 2022, at Adare General Hospital, Hawassa, South Ethiopia. A systematic random sampling method was used to select 398 study participants. Data was collected through a face-to-face interview, a medical chart review, and an ocular examination. A binary logistic regression was performed to identify potential risk factors for visual impairment and their strength of association was expressed using an adjusted odds ratio with a 95% confidence interval. Variables with a P-value of < 0.05 were considered statistically significant.

RESULT

In this study, a total of 391 participants were involved, with a response rate of 98.2%. The prevalence of visual impairment was 28.6% (95% CI: 24.6-33.0). Age ≥ 60 years (AOR = 4.03, 95% CI: 1.72, 10.71), poor physical exercise (AOR = 3.26, 95% CI: 1.62, 6.53), poor glycemic control (AOR = 4.34, 95% CI: 2.26, 8.34), history of eye examination (AOR = 2.94, 95% CI: 1.50, 5.76), duration of diabetes ≥ 9 years (AOR = 4.78, 95% CI: 2.11, 10.83) and diabetic peripheral neuropathy (AOR = 3.01, 95% CI: 1.21, 7.50) were positively associated with visual impairment.

CONCLUSION

The study found a high prevalence of visual impairment among adult diabetic patients. Older age, longer duration of diabetes, poor physical exercise, poor glycemic control, history of eye examination, and diabetic peripheral neuropathy were significantly associated with visual impairment. Thus, regular physical activity, good control of glucose levels, and regular eye exams were recommended for all diabetic patients.

Retinal Neurodegeneration in Diabetes: an Emerging Concept in Diabetic Retinopathy

PURPOSE OF REVIEW

Diabetic retinopathy (DR), the leading cause of blindness in working-aged adults, remains clinically defined and staged by its vascular manifestations. However, early retinal neurodegeneration may precede vascular pathology, suggesting that this neuronal damage may contribute to disease pathogenesis and represent an independent target for intervention. This review will discuss the evidence and implications for diabetic retinal neurodegeneration.

RECENT FINDINGS

A growing body of literature has identified progressive retinal thinning and visual dysfunction in patients with diabetes even prior to the onset of DR, though advances in retinal vascular imaging suggest that vascular remodeling and choroidal changes occur during these early stages as well. Animal models of diabetes and in vitro studies have also suggested that diabetes may directly affect the retinal neural and glial tissue, providing support to the concept that diabetic retinal neurodegeneration occurs early in the disease and suggesting potentially relevant molecular pathways. Diabetic retinal neurodegeneration may represent a "preclinical" manifestation of diabetic retinal disease and remains an active area of investigation. As the natural history and molecular mechanisms become increasingly understood, it may lead to upcoming developments in not only the treatment options but also the clinical definition of DR.