Type 2 diabetes influences intraepithelial corneal nerve parameters and corneal stromal-epithelial nerve penetration sites

Advances in diagnostic methods for early-stage diabetic polyneuropathy

Significant advancements have been made in diagnostic methods for early-stage diabetic polyneuropathy. Early and accurate diagnosis of diabetic polyneuropathy is crucial for preventing further complications and enabling timely intervention. Furthermore, there is a need for an objective numerical value to evaluate the early stage of diabetic polyneuropathy.

Effects of Diquafosol Sodium Ophthalmic Solution on Tear Film Matrix Metallopeptidase-9 and Corneal Nerve Density in Patients with Type 2 Diabetic Dry Eye

Purpose: Diabetes mellitus has been associated with increased dry eye disease (DED) and exacerbates DED's pathology. This preliminary short-term study aimed to evaluate the effects of 3% Diquafosol Sodium ophthalmic solution (DQS) on ocular surface inflammation and corneal nerve density in diabetic dry eye (DDE) patients. Methods: In this perspective, participants used 1 drop of 3% DQS (Diquas; Santen Pharmaceutical Co., Ltd., Osaka, Japan) 6 times daily for 8 weeks. Non-invasive tear breakup time (NITBUT), tear film lipid layer (TFLL), conjunctival hyperemia [redness score (RS)], corneoconjunctival staining (CFS), corneal sensitivity (CS), Meibomian gland quality (MGQ) and Meibomian gland expressibility (MGEx), corneal nerve fiber density (CNFD), and Standard Patient Evaluation Eye Dryness (SPEED) questionnaire were assessed at baseline, at weeks 4, and up to 8 weeks. Matrix metalloproteinase-9 (MMP-9) of tear samples was measured at baseline and weeks 8. Results: The mean age was 61.27 ± 11.68 years. At baseline NITBUT = 5.89 ± 2.81 s, tear meniscus height = 0.17 ± 0.05 mm, TFLL = 2.74 ± 0.51, CFS = 4.35 ± 0.68, CS = 53.83 ± 9.63 mm, MMP-9 = 49.10 ± 10.42 ng/mL, RS = 1.65 ± 0.44, MGEx = 1.85 ± 0.72, MGQ = 2.65 ± 0.50, CNFD = 20.36 ± 8.20 no./mm2, and SPEED = 12.62 ± 3.91. At week 4, significant improvements were found in all parameters except RS (1.59 ± 0.46, P = 0.172) and CNFD (21.46 ± 8.41, P = 0.163). Finally, at week 8, all parameters had significant improvements. Conclusion: Preliminary short-term findings suggest that treatment of DDE patients with DQS was found to be safe and efficacious in improving dry eye parameters. In addition, inflammatory marker and corneal nerve density were significantly improved. This study was registered with ClinicalTrials.gov (NCT05193331).

The Role of Insulin-like Growth Factor (IGF) System in the Corneal Epithelium Homeostasis-From Limbal Epithelial Stem Cells to Therapeutic Applications

The corneal epithelium, comprising three layers of cells, represents the outermost portion of the eye and functions as a vital protective barrier while concurrently serving as a critical refractive structure. Maintaining its homeostasis involves a complex regenerative process facilitated by the functions of the lacrimal gland, tear film, and corneal nerves. Crucially, limbal epithelial stem cells located in the limbus (transitional zone between the cornea and the conjunctiva) are instrumental for the corneal epithelium integrity by replenishing and renewing cells. Re-epithelialization failure results in persistent defects, often associated with various ocular conditions including diabetic keratopathy. The insulin-like growth factor (IGF) system is a sophisticated network of insulin and other proteins essential for numerous physiological processes. This review examines its role in maintaining the corneal epithelium homeostasis, with a special focus on the interplay with corneal limbal stem cells and the potential therapeutic applications of the system components.

In-vivo corneal confocal microscopy: Imaging analysis, biological insights and future directions

In-vivo corneal confocal microscopy is a powerful imaging technique which provides clinicians and researcher with the capabilities to observe microstructures at the ocular surfaces in significant detail. In this Mini Review, the optics and image analysis methods with the use of corneal confocal microscopy are discussed. While novel insights of neuroanatomy and biology of the eyes, particularly the ocular surface, have been provided by corneal confocal microscopy, some debatable elements observed using this technique remain and these are explored in this Mini Review. Potential improvements in imaging methodology and instrumentation are also suggested.