Corneal nerve changes in herpes zoster ophthalmicus: a prospective longitudinal in vivo confocal microscopy study

Bilateral In Vivo Confocal Microscopic Changes of the Corneal Subbasal Nerve Plexus in Patients with Acute Herpes Zoster Ophthalmicus

INTRODUCTION

Unilateral herpes zoster ophthalmicus (HZO) results in bilateral corneal denervation in patients with corneal involvement, which correlates with corneal sensation loss. The study aimed to analyze bilateral corneal nerve changes in patients with acute unilateral HZO and no keratitis compared with healthy controls.

METHODS

This was a prospective, single-center study. Using in vivo confocal microscopy (IVCM) and an automatized single image analysis software (ACCmetrics, University of Manchester, UK), seven corneal nerve parameters, including corneal nerve fiber density (CNFD; no/mm2), corneal nerve branch density (CNBD; no/mm2), corneal nerve fiber length (CNFL; mm/mm2), corneal nerve total branch density (CTBD; no/mm2), corneal nerve fiber area (CNFA; mm2/mm2), corneal nerve fiber width (CNFW; mm/mm2), and corneal nerve fiber fractal dimension (CFracDim) were analyzed. Additionally, central corneal sensitivity was measured.

RESULTS

Forty-six patients with HZO and 49 controls were recruited and compared. In the HZO group, ipsilateral and contralateral eyes presented a significant decrease (p < 0.001) in all seven IVCM parameters compared with controls: CNFD (13.25 ± 5.23 and 15.24 ± 4.70 vs. 23.54 ± 6.54), CNBD (14.67 ± 9.03 and 16.59 ± 7.98 vs. 31.72 ± 17.89), CNFL (8.42 ± 2.83 and 9.06 ± 2.69 vs. 13.08 ± 4.02), CTBD (27.11 ± 13.71 and 23.58 ± 12.69 vs. 46.88 ± 24.90), CNFA (0.0044 ± 0.002 and 0.0042 ± 0.001 vs. 0.0056 ± 0.002), CNFW (0.0213 ± 0.003 and 0.0221 ± 0.003 vs. 0.0222 ± 0.001) and CFracDim (1.39 ± 0.06 and 1.38 ± 0.06 vs. 1.45 ± 0.05). In the ipsilateral HZO eye group, a positive Hutchinson sign or a reduced corneal sensitivity was associated with more extensive corneal denervation. A significant negative correlation was found between patient age and CNFD (rho = - 0.312, p < 0.002), CNFL (rho = - 0.295, p = 0.004), and CFracDim (rho = - 0.284, p = 0.005).

CONCLUSIONS

Unilateral HZO in patients without apparent keratitis leads to bilateral subbasal nerve plexus alteration in the early days after disease onset, especially in those with a positive Hutchinson sign. Early follow-up of patients with HZO and bilateral application of preservative-free artificial tears during the initial months of symptom onset may help reduce the risk of developing neurotrophic keratopathy (NTK).

Emerging Treatments for Persistent Corneal Epithelial Defects

Persistent corneal epithelial defects (PCEDs) are a challenging ocular condition characterized by the failure of complete corneal epithelial healing after an insult or injury, even after 14 days of standard care. There is a lack of therapeutics that target this condition and encourage re-epithelialization of the corneal surface in a timely and efficient manner. This review aims to provide an overview of current standards of management for PCEDs, highlighting novel, emerging treatments in this field. While many of the current non-surgical treatments aim to provide lubrication and mechanical support, novel non-surgical approaches are undergoing development to harness the proliferative and healing properties of human mesenchymal stem cells, platelets, lufepirsen, hyaluronic acid, thymosin ß4, p-derived peptide, and insulin-like growth factor for the treatment of PCEDs. Novel surgical treatments focus on corneal neurotization and limbal cell reconstruction using novel scaffold materials and cell-sources. This review provides insights into future PCED treatments that build upon current management guidelines.

In vivo confocal microscopy findings about ocular surface recovery in patients following pterygium excision combined with conjunctival autograft

PURPOSE

To study cellular and neural changes around the donor and recipient areas after pterygium excision combined with autologous conjunctival transplantation using corneal confocal microscopy, we evaluated the postoperative impact of this surgical procedure.

METHODS

Patients with primary pterygium located on the nasal side who visited the Department of Ophthalmology of Wuxi Second People's Hospital between April and August 2023 were enrolled. Age-matched healthy eyes were included as the control group. IVCM was performed in the affected eyes, 6 months after pterygium excision. The images of the central conjunctival cells in the recipient and donor areas, the cells of each layer of the cornea around the recipient and donor area (around 2 mm from the nasal and upper corneal margins), and the structures of the corneal margins were recorded in the affected eyes and statistically compared with the corresponding areas in the control eyes.

RESULTS

Seventeen eyes of 14 patients with primary pterygium located on the nasal side (mean 64 ± 8.74 years old), and 17 eyes of nine patients as age-matched normal controls were included. Compared with those of normal eyes, the density of corneal pterygoid epithelium around the recipient area (5104 ± 599 cells/mm2 vs. 5700 ± 515 cells/mm2, P < 0.01) and the central conjunctival epithelial cells in the recipient areas (3984 ± 453 cells/mm2 vs. 4834 ± 244 cells/mm2, P < 0.01) were significantly lower 6 months postoperatively. However, the superficial stromal, deep stromal, and endothelial cell densities around the recipient area exhibited no significant differences (P > 0.05). Highly illuminated basal cells were visible at the nasal corneal margin, with an irregular intersection of fibrous tissue with corneal epithelial cells. More dendritic Langerhans cell infiltration was seen in the junctional area. Compared with those in the normal eyes, the densities of the corneal pterygoid epithelium (4896 ± 428 cells/mm2 vs. 5557 ± 367 cells/mm2, P < 0.01), deep stromal cells (337 ± 65 cells/mm2 vs. 419 ± 39 cells/mm2, P < 0.01), endothelial cells (2305 ± 170 cells/mm2 vs. 2547 ± 212 cells/mm2, P < 0.01) around the donor area and the central conjunctival epithelial cells (3700 ± 446 cells/mm2 vs. 4282 ± 272 cells/mm2, P < 0.01) in the donor area were significantly lower 6 months postoperatively. However, no significant differences were observed in superficial stromal cell density (P > 0.05). A slight wavy interfacial intersection was visible on the superior corneal margin, with some of the highlighted basal cells visible.

CONCLUSIONS

Pterygium excision combined with autologous conjunctival transplantation with corneal stem cells can better promote the repair of most corneal cells around the recipient area and fence-like structures of the corneal rim 6 months postoperatively, but there may be some damage to the corneal conjunctival structures around the donor area.

In-vivo confocal microscopy predicts cytomegalovirus as the cause of chronic or recurrent anterior uveitis among Chinese

PURPOSE

To evaluate and compare endothelial features by in-vivo confocal microscopy (IVCM) in Chinese eyes with chronic or recurrent anterior uveitis (AU) with and without cytomegalovirus (CMV).

METHODS

A double-masked, cross-sectional case-control study at a tertiary eye clinic.

RESULTS

Thirty eyes of 30 subjects were analyzed. Fifteen eyes (50%) were CMV positive, while fifteen eyes were negative for herpes simplex virus, varicella zoster virus and CMV. Absence of pseudoguttata was the strongest, independent risk factor for CMV (OR 34.53, 95% CI: 1.84-648.02, p = 0.018), followed by severe iris depigmentation (OR 31.45, 1.02-965.81, p = 0.048) and low corneal endothelial cell density (ECD) (OR 14.79, 1.14-191.30, p = 0.039) on univariable regression. All three remained statistically significant after adjustment. The combination of absence of pseudoguttata and low ECD on IVCM achieved a similar predictive value as iris depigmentation examination.

CONCLUSION

Absence of pseudoguttata on IVCM was an independent predictor of positive CMV detection after adjusting for iris depigmentation and corneal endothelial cell density. The addition of this feature to severe iris depigmentation and low corneal ECD can increase the positive predictive value of detecting CMV. IVCM was a useful non-invasive tool to predict CMV in patients with chronic or recurrent AU.

Artificial-Intelligence-Enhanced Analysis of In Vivo Confocal Microscopy in Corneal Diseases: A Review

Artificial intelligence (AI) has seen significant progress in medical diagnostics, particularly in image and video analysis. This review focuses on the application of AI in analyzing in vivo confocal microscopy (IVCM) images for corneal diseases. The cornea, as an exposed and delicate part of the body, necessitates the precise diagnoses of various conditions. Convolutional neural networks (CNNs), a key component of deep learning, are a powerful tool for image data analysis. This review highlights AI applications in diagnosing keratitis, dry eye disease, and diabetic corneal neuropathy. It discusses the potential of AI in detecting infectious agents, analyzing corneal nerve morphology, and identifying the subtle changes in nerve fiber characteristics in diabetic corneal neuropathy. However, challenges still remain, including limited datasets, overfitting, low-quality images, and unrepresentative training datasets. This review explores augmentation techniques and the importance of feature engineering to address these challenges. Despite the progress made, challenges are still present, such as the "black-box" nature of AI models and the need for explainable AI (XAI). Expanding datasets, fostering collaborative efforts, and developing user-friendly AI tools are crucial for enhancing the acceptance and integration of AI into clinical practice.

Corneal reinnervation in patients with severe neurotrophic keratopathy secondary to herpes zoster ophthalmicus after treatment with autologous serum tear drops

Purpose

To study potential corneal reinnervation and recovery of corneal sensation in patients with severe neurotrophic keratopathy (NK) secondary to herpes zoster ophthalmicus (HZO) after treatment with topical autologous serum tears (AST).

Method

Four cases of HZO with severe NK were followed clinically and by serial laser in vivo confocal microscopy (IVCM, HRT3/RCM, Heidelberg Engineering) before and during treatment with 20% AST drops eight times a day. Two masked observers reviewed the IVCM images and assessed corneal nerve alterations.

Results

At baseline, all patients had complete loss of corneal sensation. In addition, IVCM showed complete lack of the subbasal corneal nerve plexus in all patients. All four patients were refractory to conventional therapies and were treated with AST drops. All patients demonstrated significant nerve regeneration by IVCM within 3-7 months of treatment. The total nerve density increased to a mean ± SEM of 10,085.88±2,542.74 μm/mm2 at the last follow up. Corneal sensation measured by Cochet-Bonnet esthesiometry improved to a mean ± SEM of 3.50±1.30 cm. Interestingly, 3 of 4 patients developed stromal keratitis with ulceration within weeks of corneal reinnervation, which was reversed by adding topical steroids.

Conclusion

Autologous serum tears are effective in restoring corneal subbasal nerves and sensation in patients with severe NK secondary to HZO. However, this group of patients may require concurrent topical immunomodulation and antiviral therapy while on AST to prevent stromal keratitis.