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Early structural and functional neurovascular changes in the retina in the prediabetic stage
Dhanashree Ratra1, Rajesh Nagarajan2, Daleena Dalan2
1Department of Vitreoretinal Diseases, Medical Research Foundation, Sankara Nethralaya, Chennai, Tamil Nadu, India. dhanashreeratra@gmail.com.
Insights
Prediabetes causes early functional changes in retinal neurons, preceding structural or vascular alterations. This study highlights subtle neurovascular changes in prediabetic individuals.
Area of Science:
- Ophthalmology
- Diabetology
- Neuroscience
Background:
- Prediabetes is a growing public health concern.
- Early detection of complications is crucial for managing prediabetes.
- Retinal neurovascular changes may serve as an early indicator of diabetic complications.
Purpose of the Study:
- To investigate neurovascular alterations in the retina of prediabetic individuals.
- To compare retinal parameters between prediabetic subjects and healthy controls.
- To identify early functional and structural changes in the prediabetic retina.
Main Methods:
- Prospective study comparing prediabetic and normal control groups.
- Classification based on HbA1C, blood glucose levels, and glucose tolerance tests.
- Ophthalmic evaluation including fundus examination, OCT angiography, and multifocal electroretinogram (mfERG).
Main Results:
- No significant differences in vision, contrast sensitivity, or ganglion cell complex thickness.
- Reduced central foveal thickness and subfoveal choroidal thickness in prediabetics.
- Significantly lower mfERG amplitude in prediabetics, indicating neuronal dysfunction.
Conclusions:
- Prediabetes is associated with early functional neuronal changes in the retina.
- Retinal neuronal function is affected before apparent structural or vascular changes.
- mfERG can detect early functional deficits in prediabetic retinopathy.
Purpose:
This study was undertaken to investigate the neurovascular changes in the retina of prediabetic subjects.
Methods:
Subjects enroled in a prospective study were separated into prediabetic and normal control groups based on their glycosylated haemoglobin (HbA1C) levels, fasting and postprandial blood sugar levels and glucose tolerance test. All the subjects underwent detailed ophthalmic evaluation, which included fundus examination, fundus photography, optical coherence tomography angiography (OCTA), and multifocal electroretinogram (mfERG). Comparisons were done between the groups using the Wilcoxon signed rank test.
Results:
The median age was 48 years for the normal controls (n = 40), and 49.5 years for prediabetic subjects (n = 45) (p = 0.306). There was no difference in the vision, contrast sensitivity, thickness of the ganglion cell complex or the foveal avascular zone parameters between the groups. But the central foveal thickness and subfoveal choroidal thickness were significantly reduced in prediabetics (p < 0.01). The mfERG showed significant differences in the amplitude. The average amplitude was 35 ± 12 nv/deg2 in the normals and 29 ± 11 nv/deg2 in the prediabetics (p = 0.003). A weak positive correlation was noted between the mfERG and vascular parameters in the prediabetic group.
Conclusions:
The prediabetic stage reveals earliest functional neuronal changes in the retina. The neuronal function seems to be affected much earlier than clinically appreciable structural changes in the ganglion cell complex and precedes vascular changes in the retina.
