Assessment of Diabetic Retinopathy Vascular Density Maps

Purpose

Optical coherence tomography (OCT) and OCTA were used for qualitative and quantitative assessment of retinal vascular density in superficial capillary plexus, deep capillary plexus, foveal avascular zone, and choroidal vascular density map.

Patients and Methods

This study included 64 eyes. Diabetics and control groups were recruited from an internal medicine clinic at Misr University for Science and Technology Hospital and asked to participate in this study. This study was designed as an observational and cross-sectional study in the period from 8/2018 to 8/2019.

Results

There was a decrease in choroidal vascular density in diabetic patients. There was a decrease in retinal thickness in diabetic patients and there were no significant differences in the retinal thickness between control subjects and patients with non-diabetic retinopathy (NDR).

Conclusion

Our study suggests that OCTA can identify preclinical DR before the manifestation of clinically apparent retinopathy. Our findings also highlight the potential role of OCTA in monitoring and quantifying retinal vascular alterations in diabetics.

Analysis of Changes in Retinal Thickness in Type 2 Diabetes without Diabetic Retinopathy

OBJECTIVE

To examine the changes in retinal thickness of patients with diabetes without DR.

DESIGNS

A randomization, crossover, retrospective practice.

PARTICIPANTS

43 diabetic patients and 43 ethnic-, age-, and sex-matched controls.

METHODS

Full retinal thicknesses of ten areas were assessed using spectral domain optical coherence tomography. Confounding variables, such as age, gender, and glycated haemoglobin (HbA1c) level, were assessed by regression analysis.

MAIN OUTCOME MEASURES

Mean retinal thickness of ten areas.

RESULTS

The mean thickness of the fovea was 215.8 ± 18.9 μm in the diabetes group and 222.0 ± 18.6 μm in the control group (p = 0.04). The mean thickness of the temporal parafovea was 319.9 ± 16.7 μm in the diabetes group and 326.0 ± 14.4 μm in the control group (p = 0.01). The mean thickness of the temporal perifovea was 276.4 ± 27.9 μm in the diabetes group and 284.8 ± 17.4 μm in the control group (p = 0.02). There were no significant differences in retinal thickness between groups in other areas (p > 0.05). Regression analysis revealed that decreased retinal thickness of the temporal perifovea was associated with a higher HbA1c level (>8.7%) (p = 0.04).

CONCLUSION AND RELEVANCE

Subtle structural changes in the retina may occur in diabetes without DR. Decreased retinal thickness appeared to begin in the fovea and temporal areas. A high HbA1c level was the main factor influencing retinal thickness.

Functional Deficits Precede Structural Lesions in Mice With High-Fat Diet-Induced Diabetic Retinopathy

Obesity predisposes to human type 2 diabetes, the most common cause of diabetic retinopathy. To determine if high-fat diet-induced diabetes in mice can model retinal disease, we weaned mice to chow or a high-fat diet and tested the hypothesis that diet-induced metabolic disease promotes retinopathy. Compared with controls, mice fed a diet providing 42% of energy as fat developed obesity-related glucose intolerance by 6 months. There was no evidence of microvascular disease until 12 months, when trypsin digests and dye leakage assays showed high fat-fed mice had greater atrophic capillaries, pericyte ghosts, and permeability than controls. However, electroretinographic dysfunction began at 6 months in high fat-fed mice, manifested by increased latencies and reduced amplitudes of oscillatory potentials compared with controls. These electroretinographic abnormalities were correlated with glucose intolerance. Unexpectedly, retinas from high fat-fed mice manifested striking induction of stress kinase and neural inflammasome activation at 3 months, before the development of systemic glucose intolerance, electroretinographic defects, or microvascular disease. These results suggest that retinal disease in the diabetic milieu may progress through inflammatory and neuroretinal stages long before the development of vascular lesions representing the classic hallmark of diabetic retinopathy, establishing a model for assessing novel interventions to treat eye disease.

Diabetic macular morphology changes may occur in the early stage of diabetes

Background

The purpose of this study was to observe whether invisible morphological changes are presented in the two types of diabetes mellitus patients without diabetic retinopathy.

Methods

Twenty-six type 1 diabetes mellitus (T1DM) patients and 34 type 2 diabetes mellitus (T2DM) patients without diabetic retinopathy (DR) were recruited for this study. They underwent complete examinations that included stereoscopic color fundus photography and optical coherence tomography (OCT). The OCT patterns were used to measure the macular retinal thickness (RT), the ganglion cell and inner plexiform layer (GC-IPL) complex thickness, the inner nuclear layer (INL) thickness, the outer nuclear layer (ONL) thickness and the subfoveal choroidal thickness (SFCT) using the enhanced depth imaging (EDI) patterns and the retinal fiber layer (RNFL) thickness around the optic disc. All results were compared to those of age- and sex-matched control groups.

Results

In the patients with T1DM, the mean RT and GC-IPL complex thicknesses were significantly thinner than those of the control group (p < 0.05). The RNFL was found to be thinner at the 9 o’clock position around the optic disc in the patients compared with the control group. The SFCTs were similar in the controls and subjects. The INL and ONL were decreased in parts of the pericentral and peripheral areas in the T1DM patients (p < 0.05) and increased in the T2DM patients (p < 0.05).

Conclusions

This study demonstrated that in short-duration T1DM patients, the layers of the retina are affected and that the neural tissue has begun to be lost. As diabetes develops, neurodegeneration may cause vascular permeability, which causes thickening of the retinal layers.

New ophthalmologic imaging techniques for detection and monitoring of neurodegenerative changes in diabetes: a systematic review

Optical coherence tomography (OCT) of the retina and around the optic nerve head and corneal confocal microscopy (CCM) are non-invasive and repeatable techniques that can quantify ocular neurodegenerative changes in individuals with diabetes. We systematically reviewed studies of ocular neurodegenerative changes in adults with type 1 or type 2 diabetes and noted changes in the retina, the optic nerve head, and the cornea. Of the 30 studies that met our inclusion criteria, 14 used OCT and 16 used CCM to assess ocular neurodegenerative changes. Even in the absence of diabetic retinopathy, several layers in the retina and the mean retinal nerve fibre layer around the optic nerve head were significantly thinner (-5·36 μm [95% CI -7·13 to -3·58]) in individuals with type 2 diabetes compared with individuals without diabetes. In individuals with type 1 diabetes without retinopathy none of the intraretinal layer thicknesses were significantly reduced compared with individuals without diabetes. In the absence of diabetic polyneuropathy, individuals with type 2 diabetes had a lower nerve density (nerve branch density: -1·10/mm(2) [95% CI -4·22 to 2·02]), nerve fibre density: -5·80/mm(2) [-8·06 to -3·54], and nerve fibre length: -4·00 mm/mm(2) [-5·93 to -2·07]) in the subbasal nerve plexus of the cornea than individuals without diabetes. Individuals with type 1 diabetes without polyneuropathy also had a lower nerve density (nerve branch density: -7·74/mm(2) [95% CI -14·13 to -1·34], nerve fibre density: -2·68/mm(2) [-5·56 to 0·20]), and nerve fibre length: -2·58 mm/mm(2) [-3·94 to -1·21]). Ocular neurodegenerative changes are more evident when diabetic retinopathy or polyneuropathy is present. OCT and CCM are potentially useful, in addition to conventional clinical methods, to assess diabetic neurodegenerative changes. Additional research is needed to determine their incremental benefit and to standardise procedures before the application of OCT and CCM in daily practice.