Correlation between corneal and retinal neurodegenerative changes and their association with microvascular perfusion in type II diabetes

Abstract

Purpose The pathophysiology of diabetic neurodegeneration and microvasculopathy remains controversial. Neurosensory layer thickness and corneal nerve fibre loss represent potential biomarkers of neuropathy. The purpose of this cross‐sectional study was to determine the correlation between these neurodegenerative features and their association with retinal microvascular integrity in patients with type II diabetes without retinopathy. Methods Nerve fibre length (NFL), density (NFD) and branch density (NBD) were assessed using corneal confocal microscopy. Spectralis optical coherence tomography (OCT) was used for peripapillary retinal nerve fibre layer (RNFL), and macular RNFL, ganglion cell (GCL), inner plexiform (IPL) and inner nuclear layer (INL) thicknesses. Parafoveal vessel density (PVD) was determined using OCT angiography. Results We analysed 118 eyes of 61 patients. Peripapillary RNFL, macular RNFL, GCL, IPL and INL were 101 ± 8, 29 ± 3, 43 ± 4, 36 ± 3 and 36 ± 3 μm. NFL, NFD and NBD were 12.3 ± 4.4 mm/mm2, 17.8 ± 7.4/mm2 and 26.7 ± 15.2/mm2. Corneal nerve fibre variables were neither associated with inner retinal thicknesses nor PVD. A significant positive correlation was found between macular GCL, IPL and peripapillary RNFL with deep capillary plexus PVD (p ≤ 0.05). Conclusion Our results indicate that corneal and retinal neurodegeneration are independent changes early in type II diabetes and that distinct retinal, but not corneal neurodegenerative features, are associated with retinal microvascular perfusion.

Neurodegeneration of the cornea and retina in patients with type 1 diabetes without clinical evidence of diabetic retinopathy

“…Although we found reductions in both the RNFL and corneal nerve parameters independently, we and others (51) found no correlation between neural changes in the retina (central nervous system) and cornea (peripheral nervous system). At present, the reason for this finding is unclear.…”

Analysis of Microcirculation Changes in the Macular Area and Para-Optic Disk Region After Implantable Collamer Lens Implantation in Patients With High Myopia

“…In this study, it was found that although there was no significant difference of CRT between preoperative and postoperative, the thickness of the paracentral fovea retina in all quadrants was significantly increased 3 months after surgery, and the thickness of the nasal paracentral retina was significantly increased 3 months after surgery compared with that before surgery. In addition, the blood flow density postoperative in superficial and deep nasal paracentral fovea retina was significantly lower than that before surgery, suggesting that the decrease of GCL-IPL complex may be an important reason for the blood flow density change in superficial and deep layers after surgery ( Hafner et al, 2019 ). At present, OCTA can only evaluate the retina of optic disk area within 4.5 mm × 4.5 mm.…”

Corneal Confocal Microscopy as a Quantitative Imaging Biomarker of Diabetic Peripheral Neuropathy: A Review

“…There is mounting evidence that neurodegeneration has an important role in the pathophysiology of diabetic retinal disease and may be present even in the absence of vascular pathology [ 94 ]. There are few studies comparing alterations in corneal nerves with retinal neuropathy-linked parameter modifications in the early stages of DM2 [ 90 , 95 ]. They found a reduction in both corneal nerve parameters and in retinal nerve fiber layer (RNFL) and inner macular layer thickness of diabetic patients, but no variable of the corneal nerve fiber morphology was statistically significantly correlated with the thickness of any of the retinal layers in the macular or peripapillary region.…”